Legality of the Use of Military Commissions to Try Terrorists ( 2001 )


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  •                           Legality of the Use of Military Commissions to
    Try Terrorists
    The President possesses inherent authority under the Constitution, as Chief Executive and Commander
    in Chief of the Armed Forces of the United States, to establish military commissions to try and
    punish terrorists captured in connection with the attacks of September 11 or in connection with U.S.
    military operations in response to those attacks.
    November 6, 2001
    MEMORANDUM OPINION FOR THE COUNSEL TO THE PRESIDENT
    I. Background ...................................................................................................... 239
    II. Military Commissions May Be Used to Try All Offenses Against the
    Laws of War ................................................................................................... 240
    A. Congress Has Sanctioned the Broad Jurisdiction of Military
    Commissions to Try All Offenses Against the Laws of War................... 241
    B. Even If Congress Had Not Authorized Creation of Military
    Commissions, the President Would Have Authority as Commander
    in Chief to Convene Them....................................................................... 245
    C. The Use of Military Commissions to Inflict Punishments Without the
    Procedures Provided for Criminal Trials Under Article III, Section 2
    and the Fifth and Sixth Amendments Is Constitutionally Permissible .... 249
    1. U.S. Citizens...................................................................................... 254
    2. Enemy Aliens Seized in the United States ........................................ 256
    III. The President May Conclude That the Laws of Armed Conflict Apply to
    the Terrorist Attacks ....................................................................................... 260
    A. Determining Whether War Exists Is a Question for the Political
    Branches .................................................................................................. 261
    B. The Terrorist Attacks Have Created a Situation That Can Properly
    Be Considered War.................................................................................. 263
    1. American Precedents......................................................................... 264
    2. International Law Standards.............................................................. 270
    IV. Under the Laws of War, the Terrorists Are Unlawful Combatants
    Subject to Trial and Punishment for Violations of the Laws of War .............. 276
    You have asked us to consider whether terrorists captured in connection with
    the attacks of September 11 or in connection with ongoing U.S. operations in
    response to those attacks could be subject to trial before a military court. The
    Uniform Code of Military Justice (“UCMJ”), 
    10 U.S.C. §§ 801-946
    , authorizes
    military commissions to try “offenders or offenses that by statute or by the law of
    war may be tried by military commissions.” 
    10 U.S.C. § 821
     (2000). The Supreme
    Court has interpreted identical language (then included in Article 15 of the
    238
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    Legality of the Use of Military Commissions to Try Terrorists
    Articles of War in effect during World War II) to incorporate customary practice
    and to authorize trial by military commission 1 of any person subject to the laws of
    war for any offense under the laws of war. See Ex parte Quirin, 
    317 U.S. 1
    , 30
    (1942).
    We conclude that under 
    10 U.S.C. § 821
     and his inherent powers as Command-
    er in Chief, the President may establish military commissions to try and punish
    terrorists apprehended as part of the investigation into, or the military and
    intelligence operations in response to, the September 11 attacks. * As we outline in
    Part I, ample precedent establishes that military commissions may be used to try
    and punish (even with death) offenders under the laws of war. The President both
    has inherent authority as Commander in Chief to convene military commissions
    and has received authorization from Congress for their use to the full extent
    permitted by past executive practice. In Part II, we explain that determining
    whether the laws of war apply in this context is a political question for the
    President to determine in his role as Commander in Chief. In addition, we outline
    factors that may be considered, based on past precedents, in determining whether
    the laws of war are applicable in the present conflict with terrorist forces. We
    explain that a declaration of war is not required to create a state of war or to
    subject persons to the laws of war, nor is it required that the United States be
    engaged in armed conflict with another nation. The terrorists’ actions in this case
    are sufficient to create a state of war de facto that allows application of the laws of
    war.
    Part III addresses briefly some representative offenses that might be charged
    under the laws of war. We will address more thoroughly the charges that could be
    brought before a military commission and the procedures that would be required
    before such a commission in a subsequent memorandum.
    I. Background
    A military commission is a form of military tribunal typically used in three
    scenarios: (i) to try individuals (usually members of enemy forces) for violations
    of the laws of war; (ii) as a general court administering justice in occupied
    territory; and (iii) as a general court in an area where martial law has been declared
    1
    Section 821 refers to four forms of military tribunal: courts-martial, military commissions, provost
    courts, and “other military tribunals.” 
    Id.
     § 821. In this memorandum, we address military commis-
    sions, because that is the form of tribunal suited to hearing the charges contemplated here.
    * Editor’s Note: After this opinion was issued, the Supreme Court concluded in Hamdan v.
    Rumsfeld, 
    548 U.S. 557
    , 613 (2006), that military commissions established pursuant to a November 13,
    2001 presidential order were inconsistent with the UCMJ and common Article 3 of the Geneva
    Conventions. Following Hamdan, Congress expressly authorized a system of military commissions
    pursuant to the Military Commissions Act of 2006, Pub. L. No 109-366, 
    120 Stat. 2600
     (as amended by
    the Military Commissions Act of 2009, Pub. L. No. 111-84, tit. XVIII, 
    123 Stat. 2190
    , 2574).
    239
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    and the civil courts are closed. See generally William Winthrop, Military Law and
    Precedents 836-40 (2d ed. 1920) (“Winthrop”). The commission is convened by
    order of a commanding officer and consists of a board of officers who sit as
    adjudicators without a jury. See 
    id. at 835
    . The commission’s decision is subject to
    review by the convening authority and is not subject to direct judicial review.
    Military commissions have been used throughout U.S. history to prosecute
    violators of the laws of war. “Since our nation’s earliest days, such commissions
    have been constitutionally recognized agencies for meeting many urgent govern-
    mental responsibilities related to war. They have been called our common law war
    courts.” Madsen v. Kinsella, 
    343 U.S. 341
    , 346-47 (1952). Military commissions
    have tried offenders drawn from the ranks of aliens and citizens alike charged with
    war crimes arising as early as the Revolutionary War, the Mexican-American War,
    and the Civil War, and as recently as World War II. See Quirin, 
    317 U.S. at
    32
    n.10, 42 n.14. President Lincoln’s assassins and their accomplices were impris-
    oned and even executed pursuant to convictions rendered by military commis-
    sions. Their offenses were characterized not as criminal matters but rather as acts
    of rebellion against the government itself. See Military Commissions, 11 Op. Att’y
    Gen. 297 (1865); Ex parte Mudd, 
    17 F. Cas. 954
     (S.D. Fla. 1868) (No. 9899).
    Such use of military commissions has been repeatedly endorsed by federal courts,
    including as recently as this year. See Mudd v. Caldera, 
    134 F. Supp. 2d 138
    (D.D.C. 2001).
    Military commissions are not courts within Article III of the Constitution, nor
    are they subject to the jury trial requirements of the Fifth and Sixth Amendments
    of the Constitution. See Quirin, 
    317 U.S. at 40
    . Unlike Article III courts, the
    powers of military commissions are derived not from statute, but from the laws of
    war. See Ex parte Vallandigham, 68 U.S. (1 Wall.) 243, 249-53 (1863). That is,
    their authority derives from the Constitution’s vesting of the power of Commander
    in Chief in the President. “Neither their procedure nor their jurisdiction has been
    prescribed by statute.” Madsen, 
    343 U.S. at 347
    . Instead, “[i]t has been adapted in
    each instance to the need that called it forth.” 
    Id. at 347-48
    . “In general . . .
    [Congress] has left it to the President, and the military commanders representing
    him, to employ the commission, as occasion may require, for the investigation and
    punishment of violations of the laws of war.” 
    Id.
     at 346 n.9 (quoting Winthrop at
    831).
    II. Military Commissions May Be Used to Try All Offenses Against
    the Laws of War
    The Uniform Code of Military Justice (“UCMJ”) expressly addresses the use of
    military commissions in Article 21. See 
    10 U.S.C. § 821
    . Because that provision
    contains an explicit congressional authorization for military commissions, we
    begin by examining in Part II.A the scope of that authorization. We conclude that
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    Legality of the Use of Military Commissions to Try Terrorists
    section 821 is quite broad and, by endorsing the customary uses of military
    commissions in U.S. military practice, authorizes military commission jurisdiction
    to try all offenses against the laws of war. Next, in part II.B, we explain that even
    if Congress had not sanctioned the use of military commissions to try all offenses
    against the laws of war, the President, exercising his authority as Commander in
    Chief, could order the creation of military commissions to try such offenses.
    Indeed, military commissions were created under presidential authority before
    they had any sanction in statutory law. Finally, in Part II.C, we examine constitu-
    tional objections that might be raised against the use of military commissions,
    particularly potential claims that they violate constitutional guarantees for trial by
    jury and a grand jury indictment. We conclude, as has the Supreme Court, that
    offenses charged under the laws of war before military commissions are outside
    the provisions of Article III and the Fifth and Sixth Amendments and thus that the
    rights to grand jury indictment and jury trial do not apply to such offenses.
    A. Congress Has Sanctioned the Broad Jurisdiction of Military
    Commissions to Try All Offenses Against the Laws of War
    The UCMJ addresses the jurisdiction of military commissions in Article 21,
    which is section 821 of title 10 of the United States Code. Section 821 is phrased
    somewhat unusually, because it does not create military commissions and define
    their functions and jurisdiction. Instead, it refers to military commissions primarily
    to acknowledge their existence and to preserve their existing jurisdiction. As
    explained more fully below, military commissions had been created under the
    authority of the President as Commander in Chief and used to try offenses against
    the laws of war before there was any explicit statutory sanction for their use.
    Section 821, which is entitled “Jurisdiction of courts-martial not exclusive,” thus
    states that “[t]he provisions of this chapter conferring jurisdiction upon courts-
    martial do not deprive military commissions . . . of concurrent jurisdiction with
    respect to offenders or offenses that by statute or by the law of war may be tried by
    military commissions.” 
    10 U.S.C. § 821
     (emphasis added). The jurisdictional
    provision for courts-martial that is cross-referenced is 
    10 U.S.C. § 818
     (2000),
    which defines the jurisdiction of general courts-martial to include “jurisdiction to
    try any person who by the law of war is subject to trial by a military tribunal.” By
    its terms, section 821 takes the existence of military commissions as a given and
    clarifies that the establishment of broad jurisdiction in courts-martial will not
    curtail the powers of military commissions.
    By expressly preserving the jurisdiction of military commissions, section 821
    necessarily provides a congressional authorization and sanction for their use.
    Indeed, the Supreme Court has concluded that identical language in the predeces-
    sor provision to section 821—Article 15 of the Articles of War—“authorized trial
    of offenses against the laws of war before such commissions.” Quirin, 
    317 U.S. at
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    29 (emphasis added). See also 
    id. at 28
     (“By the Articles of War, and especially
    Article 15, Congress has explicitly provided, so far as it may constitutionally do
    so, that military tribunals shall have jurisdiction to try offenders or offenses
    against the law of war . . . .”).
    The fact that section 821 acknowledges and endorses the jurisdiction of an
    existing tribunal is important for properly understanding the scope of the authori-
    zation it contains. By its terms, the provision incorporates by reference the role of
    military commissions under the customary “law of war.” Thus, the section states
    that military commissions have jurisdiction over all “offenders or offenses that by
    statute or by the law of war may be tried by military commissions.” The apparent
    circularity of the language is explained by the fact that the section is endorsing the
    existing use of military commissions under military practice.
    The history of the provision also makes it abundantly clear that its purpose was
    to express congressional approval for the traditional use of military commissions
    under past practice. When the language now codified in section 821 was first
    included in the Articles of War in 1916, it was explicitly intended to acknowledge
    and sanction the pre-existing jurisdiction of military commissions. The language
    was introduced as Article 15 of the Articles of War at the same time that the
    jurisdiction of general courts-martial was expanded to include all offenses against
    the laws of war. The new Article 15 stated (like current section 821) that the
    “provisions of these articles conferring jurisdiction upon courts-martial shall not
    be construed as depriving military commissions . . . of concurrent jurisdiction in
    respect of offenders or offenses that by the law of war may be lawfully triable by
    such military commissions.” Act of August 29, 1916, 
    39 Stat. 619
    , 653. Judge
    Advocate General of the Army Crowder, the proponent of the new article,
    explained in testimony before the Senate that the military commission “is our
    common-law war court,” and that “[i]t has no statutory existence.” S. Rep. No. 64-
    130, at 40 (1916). The new Article 15 thus was not establishing military commis-
    sions and defining their jurisdiction. Rather, as General Crowder explained, it was
    recognizing their existence and preserving their authority: “It just saves to these
    war courts the jurisdiction they now have and makes it concurrent with courts-
    martial . . . .” Id.; see also S. Rep. No. 63-229, at 53 (1914) (testimony of Judge
    Advocate General Crowder before the House Committee on Military Affairs)
    (noting that the military commission “has not been formally authorized by statute”
    and explaining that the new Article 15 was designed to make clear that, through
    the expansion of the jurisdiction of courts-martial, the military commissions’
    “common law of war jurisdiction was not ousted”).
    In explaining the history of the provision now codified in section 821, the
    Supreme Court has described the testimony of Judge Advocate General Crowder
    as “authoritative.” Madsen, 
    343 U.S. at 353
    . The Court thus determined that the
    effect of this language was to preserve for such commissions “the existing
    jurisdiction which they had over such offenders and offenses” under the laws of
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    Legality of the Use of Military Commissions to Try Terrorists
    war. 
    Id. at 352
     (emphasis added). As the Court noted, because the statute simply
    recognized the existence of military commissions, “[n]either their procedure nor
    their jurisdiction has been prescribed by statute.” 
    Id. at 347
    . As explained below,
    the fact that military commissions were used long before any reference to them
    appeared in the Articles of War demonstrates that the President has authority as
    Commander in Chief to create them without authorization (and free from any
    restriction) of Congress.
    Given the text and history of section 821, the provision must be read as preserv-
    ing the broadest possible sweep for the traditional jurisdiction exercised by
    military commissions before they were expressly mentioned in statutory law. The
    statute, in other words, simply endorses and incorporates by reference Executive
    Branch practice. The Supreme Court has adopted precisely this understanding of
    the section and has thus explained that “[b]y . . . recognizing military commissions
    in order to preserve their traditional jurisdiction over enemy combatants unim-
    paired by the Articles [of War], Congress gave sanction . . . to any use of the
    military commission contemplated by the common law of war.” In re Yamashita,
    
    327 U.S. 1
    , 20 (1946) (emphasis added); see also 
    id. at 7
     (stating that Congress
    “recognized the ‘military commission’ appointed by military command, as it had
    previously existed in United States Army Practice, as an appropriate tribunal for
    the trial and punishment of offenses against the law of war”). Similarly, the Court
    has explained that “Congress has incorporated by reference, as within the jurisdic-
    tion of military commissions, all offenses which are defined as such by the law of
    war.” Quirin, 
    317 U.S. at 30
     (emphasis added); see also 
    id. at 35
     (relying on the
    “long course of practical administrative construction by [the] military authori-
    ties”). 2 Congress did not “attempt[] to codify the law of war or to mark its precise
    boundaries.” Yamashita, 
    327 U.S. at 7
    . Instead, it simply adopted by reference
    “the system of military common law.” 
    Id. at 8
    .
    Indeed, if section 821 were read as restricting the use of military commissions
    and prohibiting practices traditionally followed, it would infringe on the Presi-
    dent’s express constitutional powers as Commander in Chief. Cf. Quirin, 
    317 U.S. at 47
     (declining to “inquire whether Congress may restrict the power of the
    Commander in Chief to deal with enemy belligerents” by restricting use of
    military commissions); 
    id.
     (declining also to “consider the question whether the
    President is compelled by the Articles of War to afford unlawful enemy belliger-
    ents a trial before subjecting them to disciplinary measures”). A clear statement of
    congressional intent would be required before a statute could be read to effect such
    an infringement on core executive powers. See, e.g., Public Citizen v. U.S. Dep’t
    of Justice, 
    491 U.S. 440
    , 466 (1989).
    2
    The use of military commissions for members of the U.S. armed forces may be restricted by
    separate provisions in the UCMJ, and we do not address that issue here.
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    The congressional sanction for the use of military commissions is a permissible
    exercise of Congress’s powers under the Constitution. Congress has authority not
    only to “declare War,” but also to “raise and support Armies,” and “make Rules
    for the Government and Regulation of the land and naval Forces.” U.S. Const.
    art. I, § 8, cls. 11, 12, 14. To the extent military commissions are used for enforc-
    ing discipline within the armed forces of the United States, Congress has authority
    to sanction their use. In addition, Congress has authority to “define and punish . . .
    Offences against the Law of Nations.” Id. art. I, § 8, cl. 10. Authorizing the use of
    military commissions to enforce the laws of war—which are considered a part of
    the “Law of Nations”—is certainly a permissible exercise of these authorities. See,
    e.g., Yamashita, 
    327 U.S. at 7
     (explaining that congressional sanction for military
    commissions was an “exercise of the power conferred upon it by Article I, § 8,
    cl. 10 of the Constitution to ‘define and punish . . . Offenses against the Law of
    Nations . . .’ of which the law of war is a part”) (alteration in original); id. at 16
    (“Congress in the exercise of its constitutional power to define and punish offenses
    against the law of nations, of which the law of war is a part, has recognized the
    ‘military commission’ appointed by military command, as it had previously
    existed in United States army practice, as an appropriate tribunal for the trial and
    punishment of offenses against the law of war.”). 3 Or, to be more precise, it is
    permissible at least so long as any congressional regulations do not interfere with
    the President’s authority as Commander in Chief. Cf. Quirin, 
    317 U.S. at 47
    (declining to address “whether Congress may restrict the power of the Commander
    in Chief to deal with enemy belligerents” through regulations on military commis-
    sions); cf. also Hamilton v. Dillin, 88 U.S. (21 Wall.) 73, 87 (1874) (stating that
    the “President alone” is “constitutionally invested with the entire charge of hostile
    operations”). Given that section 821 simply gives sanction to the existing practice
    of the Executive in making use of military commissions, it does not on its face
    place any such restriction on the use of commissions.
    3
    See also Quirin, 
    317 U.S. at 28
     (“Congress, in addition to making rules for the government of our
    Armed Forces, has thus exercised its authority to define and punish offenses against the law of nations
    by sanctioning . . . the jurisdiction of military commissions to try persons for offenses which, according
    to the rules and precepts of the law of nations, and more particularly the law of war, are cognizable by
    such tribunals.”); cf. Madsen, 
    343 U.S. at
    346 n.9 (“[I]t is those provisions of the Constitution which
    empower Congress to ‘declare war’ and ‘raise armies,’ and which, in authorizing the initiation of war,
    authorize the employment of all necessary and proper agencies for its due prosecution, from which this
    tribunal derives its original sanction. . . . The commission is simply an instrumentality for the more
    efficient execution of the war powers vested in Congress and the power vested in the President as
    Commander-in-chief in war.”) (quoting Winthrop at 831).
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    Legality of the Use of Military Commissions to Try Terrorists
    B. Even If Congress Had Not Authorized Creation of Military
    Commissions, the President Would Have Authority as Commander
    in Chief to Convene Them
    The congressional authorization for military commissions in 
    10 U.S.C. § 821
    endorses sufficiently broad jurisdiction for the commissions that there will likely
    be no need to rely solely on the President’s inherent authority as Commander in
    Chief to convene commissions in the present circumstances. As noted above,
    Congress has endorsed the pre-existing practice of permitting military commis-
    sions to try “all offenses which are defined as such by the law of war.” Quirin, 
    317 U.S. at 30
    . It is important, nevertheless, to note that the President has inherent
    authority as Commander in Chief to convene such tribunals even without authori-
    zation from Congress.
    The Commander in Chief Clause, U.S. Const. art. II, § 2, cl. 1, vests in the
    President the full powers necessary to prosecute successfully a military campaign.
    It has long been understood that the Constitution provides the federal government
    all powers necessary for the execution of the duties the Constitution describes. As
    the Supreme Court explained in Johnson v. Eisentrager, “[t]he first of the
    enumerated powers of the President is that he shall be Commander-in-Chief of the
    Army and Navy of the United States. And, of course, grant of war power includes
    all that is necessary and proper for carrying these powers into execution.” 
    339 U.S. 763
    , 788 (1950) (citation omitted); see also Lichter v. United States, 
    334 U.S. 742
    ,
    780 (1948) (“The powers of Congress and the President are only those which are
    to be derived from the Constitution but . . . the primary implication of a war power
    is that it shall be an effective power to wage the war successfully.”); Home
    Building & Loan Ass’n v. Blaisdell, 
    290 U.S. 398
    , 426 (1934) (stating that “the
    war power of the federal government” is “a power to wage war successfully”).
    One of the necessary incidents of authority over the conduct of military operations
    in war is the power to punish enemy belligerents for violations of the laws of war.
    The laws of war exist in part to ensure that the brutality inherent in war is confined
    within some limits. It is essential for the conduct of a war, therefore, that an army
    have the ability to enforce the laws of war by punishing transgressions by the
    enemy. 4
    It was well recognized at the time of the Founding, moreover, that one of the
    powers inherent in military command was the authority to institute tribunals for
    punishing violations of the laws of war by the enemy. In 1780, during the
    Revolutionary War, General Washington as Commander in Chief of the Continen-
    4
    Cf. Request of the Senate for an Opinion as to the Powers of the President “In Emergency or State
    of War,” 39 Op. Att’y Gen. 343, 347-48 (1939) (“It is universally recognized that the constitutional
    duties of the Executive carry with them the constitutional powers necessary for their proper perfor-
    mance.”).
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    tal Army appointed a “Board of General Officers” to try the British Major André
    as a spy. See Quirin, 
    317 U.S. at
    31 n.9; Proceedings of a Board of General
    Officers, Held by Order of His Excellency Gen. Washington, Commander in Chief
    of the Army of the United States of America, Respecting Major John André,
    Adjutant General of the British Army, September 29, 1780 (Philadelphia, Francis
    Bailey 1780), as reprinted in Proceedings of a Board of General Officers Respect-
    ing Major John André (New York 1867), available at http://archive.org/details/
    proceedingsofboa00andr (last visited May 22, 2012). At the time, there was no
    provision in the American Articles of War providing for jurisdiction in a court-
    martial to try an enemy for the offense of spying. See George B. Davis, A Treatise
    on the Military Law of the United States 308 n.1 (1913) (“Davis”) (explaining that
    the tribunal used to try André cannot properly be considered a court-martial,
    because under the then-existing Articles of War, courts-martial could not try
    members of the enemy forces for the offense of spying); Winthrop at 961 (reprint-
    ing American Articles of War of 1776). The term “Commander in Chief” was
    understood in Anglo-American constitutional thought as incorporating the fullest
    possible range of power available to a military commander. See John Yoo, The
    Continuation of Politics by Other Means: The Original Understanding of War
    Powers, 
    84 Calif. L. Rev. 167
    , 252-54 (1996). In investing the President with full
    authority as Commander in Chief, the drafters of the Constitution surely intended
    to give the President the same authority that General Washington possessed during
    the Revolutionary War to convene military tribunals to punish offenses against the
    laws of war.
    The history of military commissions bears out this conclusion, because as a
    matter of practice military commissions have been created under the President’s
    inherent authority as Commander in Chief without any authorization from
    Congress. In April, 1818, for example, General Andrew Jackson convened
    military tribunals to try two English subjects, Arbuthnot and Ambrister, for
    inciting the Creek Indians to war with the United States. See Winthrop at 464, 832.
    The subjects were convicted and executed accordingly. 
    Id.
     As one author ex-
    plained, General Jackson “did not find his authority to convene [these tribunals] in
    the statutory law, but in the laws of war.” William E. Birkhimer, Military Gov-
    ernment and Martial Law 353 (3d ed. 1914) (“Birkhimer”). Similarly, in the
    Mexican American War in 1847, General Winfield Scott appointed tribunals
    called “council[s] of war” to try offenses under the laws of war and tribunals
    called “military commission[s]” to serve essentially as occupation courts adminis-
    tering justice for occupied territory. See, e.g., Winthrop at 832-33; Davis at 308.
    There was no statutory authorization for these tribunals, and they were thus
    instituted by military command (necessarily under authority derived from the
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    Legality of the Use of Military Commissions to Try Terrorists
    President’s authority as Commander in Chief) without sanction from Congress. 5 In
    later practice, both functions (that is, the role of war courts and courts of occupa-
    tion) were performed by tribunals known as “military commission[s].” Thus, after
    the outbreak of the Civil War, military commissions were convened to try offenses
    against the laws of war, see Davis at 308 n.2, and under the general orders drafted
    for the governance of the Army in 1862, commanders were authorized to convene
    military commissions to try offenses against the laws of war, see Winthrop at 833.
    It was not until 1863 that military commissions were even mentioned in a statute
    enacted by Congress. In that year, Congress authorized the use of military
    commissions to try members of the military for certain offenses committed during
    time of war. See Act of Mar. 3, 1863, § 30, 
    12 Stat. 731
    , 736. The statute,
    moreover, did not purport to create military commissions. Rather, it acknowledged
    that they could be used as alternatives to courts-martial in some cases.
    As explained above, the current provision in section 821 of the UCMJ also does
    not create military commissions or define exhaustively their authority. Instead, its
    history shows that it was adopted to preserve the jurisdiction of what was recog-
    nized as a pre-existing tribunal. Precisely because it confirms that military
    commissions existed before any express congressional authorization, the history of
    section 821 also supports the conclusion that the President has constitutional
    authority to convene commissions even without legislation authorizing them.
    Subsequent discussions of the use of military commissions by the Supreme
    Court reflect the same understanding that the use of military tribunals is a
    necessary part of the tools of a commander conducting a military campaign. For
    example, as the Court explained in Yamashita, “[a]n important incident to the
    conduct of war is the adoption of measures by the military commander, not only to
    repel and defeat the enemy, but to seize and subject to disciplinary measures those
    enemies who, in their attempt to thwart or impede our military effort, have
    violated the law of war.” 
    327 U.S. at 11
    . Although the Court was addressing a
    situation in which Congress had recognized this power in the commander of armed
    forces, the logic of the Court’s explanation suggests that the power to convene
    military commissions is an inherent part of the authority the Constitution confers
    upon the President by naming him Commander in Chief of the armed forces. 6
    5
    See Davis at 308 (explaining that military commissions “are simply criminal war-courts, resorted
    to for the reason that the jurisdiction of courts-martial, created as they are by statute, is restricted by
    law, and cannot be extended to include certain classes of offenses, which in war would go unpunished
    in the absence of a provisional forum for the trial of the offenders”).
    6
    See also Winthrop at 57 ([T]he “President is invested with a general and discretionary power to
    order statutory courts-martial for the army, by virtue of his constitutional capacity as Commander-in-
    chief, independently of any article of war or other legislation of Congress.”); id. at 835 (“The
    President, as Commander-in-chief, may of course assemble military commissions as he may assemble
    courts-martial.”); Birkhimer at 357 (“Military commissions may be appointed either under provisions
    of law in certain instances, or under that clause of the Constitution vesting the power of commander-in-
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    Similarly, the same conclusion is buttressed by the reasoning Justice Douglas
    advanced in support of the President’s authority to establish the international war
    crimes tribunals after World War II without any authorization from Congress. As
    Justice Douglas explained:
    The Constitution makes the President the “Commander in Chief of
    the Army and Navy of the United States . . . .” Art. II, § 2, Cl. 1. His
    power as such is vastly greater than that of troop commander. He not
    only has full power to repel and defeat the enemy; he has the power
    to occupy the conquered country, and to punish those enemies who
    violated the law of war.
    Hirota v. MacArthur, 
    338 U.S. 197
    , 207-08 (1948) (Douglas, J., concurring)
    (alteration in original, citations omitted); see also 
    id. at 215
     (“[T]he capture and
    control of those who were responsible for the Pearl Harbor incident was a political
    question on which the President as Commander-in-Chief, and as spokesman for
    the nation in foreign affairs, had the final say.”). As the Supreme Court recognized
    in Hirota, the President’s power as Commander in Chief extended to the novel
    creation of new, multinational tribunals to try the enemy for war crimes. Given
    that broad authority, the President’s power surely extends to the appointment of
    military commissions consisting solely of American officials.
    An opinion of the Attorney General issued at the end of the Civil War supports
    the same conclusion. In 1865, Attorney General Speed addressed the use of
    military commissions to try those accused in the plot to assassinate President
    Lincoln and explained that even if Congress had not provided for the creation of
    military commissions, they could be instituted by military commanders as an
    inherent incident of their authority to wage the military campaign:
    [M]ilitary tribunals exist under and according to the laws and usages
    of war in the interest of justice and mercy. They are established to
    save human life, and to prevent cruelty as far as possible. The com-
    mander of an army in time of war has the same power to organize
    military tribunals and execute their judgments that he has to set his
    squadrons in the field and fight battles. His authority in each case is
    from the law and usage of war.
    Military Commissions, 11 Op. Att’y Gen. at 305. The Attorney General thus
    concluded that “in default of Congress defining . . . the mode of proceeding to
    ascertain whether an offense [against laws of war] has been committed,” the
    chief in the President, who may exercise it either directly or through subordinate commanders.”)
    (footnote omitted).
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    Legality of the Use of Military Commissions to Try Terrorists
    commander of the armed forces could institute tribunals to undertake the task. 
    Id. at 310
    .
    The Supreme Court has never squarely addressed the question whether the
    President may convene military commissions wholly without congressional
    authorization. In Quirin, the Court expressly declined to decide “to what extent the
    President as Commander in Chief has constitutional power to create military
    commissions without the support of Congressional legislation.” 
    317 U.S. at 29
    .
    And in later cases the Court has remained uncommitted. Thus, in Madsen, for
    example, the Court stated that “[i]n the absence of attempts by Congress to limit
    the President’s power, it appears that, as Commander-in-Chief of the Army and
    Navy of the United States, he may, in time of war, establish and prescribe the
    jurisdiction and procedure of military commissions.” Madsen, 
    343 U.S. at 348
    . At
    the same time, however, the Court cautioned that the “policy of Congress to
    refrain from legislating in this uncharted area does not imply its lack of power to
    legislate.” 
    Id. at 348-49
    .
    For the reasons outlined above, we conclude that the best understanding of the
    Constitution is that the President does have the power, as Commander in Chief, to
    create military commissions to try enemy belligerents for offenses against the laws
    of war even in the absence of the congressional sanction for their use in section
    821.
    C. The Use of Military Commissions to Inflict Punishments
    Without the Procedures Provided for Criminal Trials Under
    Article III, Section 2 and the Fifth and Sixth Amendments Is
    Constitutionally Permissible
    The most likely constitutional issue to be raised concerning military commis-
    sions would be an objection to the denial of the rights to trial by jury in criminal
    cases and grand jury indictment as provided in Article III, Section 2 and the Fifth
    and Sixth Amendments. 7 Such objections would most likely be raised with respect
    to military commissions convened within the territorial United States, and we
    address them in that context. We believe that if a particular use of military
    commissions to try offenses against the laws of war is constitutionally permissible
    within the United States, it follows a fortiori that such a use is permissible to deal
    with enemy belligerents overseas, where many constitutional protections would
    not apply in any event.
    7
    Article III, Section 2 provides: “The Trial of all Crimes, except in Cases of Impeachment; shall be
    by Jury . . . .” The Fifth Amendment provides: “No person shall be held to answer for a capital, or
    otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases
    arising in the land or naval forces . . . .” The Sixth Amendment provides: “In all criminal prosecutions,
    the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and
    district wherein the crime shall have been committed . . . .”
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    It has long been settled that the guarantees to trial by jury in criminal cases
    contained in the Constitution were not intended to expand the rights to these
    procedures beyond those that existed at common law. See, e.g., Callan v. Wilson,
    
    127 U.S. 540
    , 549 (1888). As Justice Story explained in his Commentaries, in
    these provisions, the Constitution “does but follow out the established course of
    the common law in all trials for crimes,” Joseph Story, 2 Commentaries on the
    Constitution of the United States § 1791 (1833), and thus the provisions in Article
    III and the Sixth Amendment are “to be taken as a declaration of what those rules
    were.” Callan, 
    127 U.S. at 549
    . To the extent that certain offenses, even if
    technically deemed “criminal,” could be tried without indictment and without a
    jury at common law, the Supreme Court has consistently held that they may be
    tried without a jury under the Constitution. Thus, petty offenses triable at common
    law without a jury may be tried without a jury under the Constitution, see Schick v.
    United States, 
    195 U.S. 65
    , 68-70 (1904), as can criminal contempts, see, e.g., In
    re Terry, 
    128 U.S. 289
    , 303 (1888). See also Lewis v. United States, 
    518 U.S. 322
    ,
    325 (1996) (“It is well established that the Sixth Amendment, like the common
    law, reserves this jury trial right for prosecutions of serious offenses, and that
    ‘there is a category of petty crimes or offenses which is not subject to the Sixth
    Amendment jury trial provision.’”) (quoting Duncan v. Louisiana, 
    391 U.S. 145
    ,
    159 (1968)). The Fifth Amendment right to grand jury indictment similarly arises
    out of the common law. See Smith v. United States, 
    360 U.S. 1
    , 9 (1959) (“The use
    of indictments in all cases warranting serious punishment was the rule at common
    law” and “[t]he Fifth Amendment made the rule mandatory”) (citations omitted);
    Ex parte Wilson, 
    114 U.S. 417
    , 423 (1885) (“The fifth amendment, declaring in
    what cases a grand jury should be necessary, . . . in effect, affirm[ed] the rule of
    the common law upon the same subject”).
    At the time of the Founding, it was well settled that offenses under the laws of
    war were a distinct category of offense, unlike criminal offenses against the civil
    law, and were subject to trial in military tribunals without the benefits of the
    procedures of the common law enshrined in the Constitution. The Articles of War
    of 1776, for example, made it clear that courts-martial could be convened to try
    offenders under the Articles without a jury or grand jury. See Winthrop at 967
    (reproducing Articles). Similarly, as noted above, a “Board of General Officers”
    was used in 1780 to try the British Major André on the offense of spying. See
    Quirin, 
    317 U.S. at
    31 n.9. Indeed, throughout the Revolutionary War, military
    tribunals were used to try offenders without a jury. See 
    id.
     at 42 n.14. The text of
    the Constitution itself makes the distinct nature of military tribunals clear, as the
    Fifth Amendment expressly excludes “cases arising in the land or naval forces”
    from the guarantee of a grand jury indictment. U.S. Const. amend. V. Cf.
    Middendorf v. Henry, 
    425 U.S. 25
    , 49-50 (1976) (Powell, J., concurring) (“Court-
    martial proceedings, as a primary means for the regulation and discipline of the
    Armed Forces, were well known to the Founding Fathers. The procedures in such
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    Legality of the Use of Military Commissions to Try Terrorists
    courts were never deemed analogous to, or required to conform with, procedures
    in civilian courts.”). Precisely because military discipline was viewed as wholly
    apart from the ordinary criminal law and the provisions in the Constitution relating
    to it, the Supreme Court has long recognized that military commissions do not
    exercise judicial power under Article III and are not subject to judicial review. See,
    e.g., Vallandigham, 
    68 U.S. 243
    . Thus, under the settled understanding that the
    rights to jury trial and grand jury indictment do not extend beyond the cases where
    they were available at common law, those rights simply do not extend to trials
    before military tribunals for offenses against the laws of war. Such trials never
    included indictment or jury trial at the time of the Founding.
    The Supreme Court endorsed precisely this reasoning to reject constitutional
    challenges to the use of military commissions to try and execute violators of the
    laws of war during and after World War II. In Quirin, for example, eight German
    saboteurs were apprehended in the United States by the FBI, turned over to the
    military, tried by military commission, and sentenced to death. See 
    317 U.S. at 18-24
    . In addressing a petition for habeas corpus, the Supreme Court addressed
    precisely the question at issue—“whether it is within the constitutional power of
    the National Government to place [these defendants] upon trial before a military
    commission”—without the protections of Article III and the Fifth and Sixth
    Amendments. 
    Id. at 29
    .
    The Court concluded that there was no constitutional barrier to use of the mili-
    tary commission. As the Court explained, the guarantees in Article III and the
    Fifth and Sixth Amendments must be understood in light of the common law at the
    time of the Founding. Military tribunals, the Court noted, “are not courts in the
    sense of the Judiciary Article,” and juries had never been part of their procedures.
    
    Id. at 39
    . In particular, the Court pointed to a statute of 1806 concerning trials for
    spies as reflective of the contemporary understanding of the constitutional
    guarantees. That statute imposed the death penalty on alien spies “according to the
    law and usage of nations, by sentence of a general court martial.” Act of Apr. 10,
    1806, ch. 20, § 2, 
    2 Stat. 359
    , 371. As the Court explained, this “enactment must
    be regarded as a contemporary construction of both Article III, Section 2, and the
    Amendments as not foreclosing trial by military tribunals, without a jury, of
    offenses against the laws of war committed by enemies not in or associated with
    our Armed Forces.” 
    317 U.S. at 41
    . Thus, the Court concluded that offenses
    cognizable under the laws of war in military tribunals at the time of the Founding
    could continue to be tried before such tribunals under the Constitution: “In the
    light of this long-continued and consistent interpretation we must conclude that § 2
    of Article III and the Fifth and Sixth Amendments cannot be taken to have
    extended the right to demand a jury to trials by military commission, or to have
    required that offenses against the laws of war not triable by jury at common law be
    tried only in the civil courts.” Id. at 40.
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    The Court reaffirmed that conclusion in subsequent cases. See Yamashita, 
    327 U.S. 1
     (trial by U.S. military commission of Japanese military governor of the
    Phillippines for various war crimes committed under his command); Johnson v.
    Eisentrager, 
    339 U.S. 763
    , 787-90 (1950) (trial of German officers in China by
    U.S. military commission for aiding Japanese after Germany’s surrender); 
    id. at 786
     (“The jurisdiction of military authorities, during or following hostilities, to
    punish those guilty of offenses against the laws of war is long established.”); cf.
    Duncan v. Kahanamoku, 
    327 U.S. 304
    , 313-14 (1946) (referring to the “well-
    established power of the military to exercise jurisdiction over . . . enemy belliger-
    ents, prisoners of war, or others charged with violating the laws of war”). 8
    As the Quirin and Yamashita Courts explained, their decisions rested upon
    long-established practice throughout the history of the United States—extending
    back to the Founding and before—demonstrating that any enemy belligerent
    charged with a violation of the laws of war may be tried by military tribunal. The
    Court traced the history of military commissions explained above and noted,
    among others, the use of boards functionally equivalent to military commissions in
    the Revolutionary War, see Quirin, 
    317 U.S. at
    31 n.9, the Mexican-American
    War, see 
    id.
     at 32 n.10, and during and after the Civil War, 
    id.
     Military commis-
    sions, in fact, were used to try those charged with the assassination of President
    Lincoln. See Military Commissions, 11 Op. Att’y Gen. 297; Mudd, 
    17 F. Cas. 954
    .
    The primary support for constitutional arguments to restrict the use of military
    commissions would be based on the Supreme Court’s decision in Ex parte
    Milligan, 71 U.S. (4 Wall.) 2 (1866). There, the Court held that a military
    commission could not be used to try a U.S. citizen in the United States for alleged
    violations of the laws of war, except in areas where martial law has been pro-
    claimed and the civil courts are closed. See 
    id. at 121-22
    . In Milligan, a U.S.
    citizen resident in Indiana was arrested by the military, charged with providing aid
    and comfort to the Confederacy, tried by military commission, and sentenced to
    death. See 
    id. at 107-08
    . In addressing a petition for a writ of habeas corpus, the
    Court rejected the suggestion that the President had full authority to use military
    commissions to the extent permitted by the “‘laws and usages of war.’” 
    Id. at 121
    .
    The Court refused even to inquire into what those usages might be, because “they
    can never be applied to citizens in states which have upheld the authority of the
    government, and where the courts are open and their process unobstructed.” Id.;
    see also 
    id. at 123
     (noting that persons in military service are subject to military
    tribunals, but “[a]ll other persons, citizens of states where the courts are open . . .
    are guaranteed the inestimable privilege of trial by jury”); 
    id. at 121-22
     (“[N]o
    8
    After World War II, entirely apart from the trials before the International Military Tribunal at
    Nuremberg, U.S. military commissions in Germany tried 177 Nazi officials and sentenced 12 to death.
    See Spencer J. Crona & Neal A. Richardson, Justice for War Criminals of Invisible Armies: A New
    Legal and Military Approach to Terrorism, 
    21 Okla. City U. L. Rev. 349
    , 381 (1996) (“Crona &
    Richardson”).
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    Legality of the Use of Military Commissions to Try Terrorists
    usage of war could sanction a military trial there [in Indiana, where courts were
    always open] for any offence whatever of a citizen in civil life, in nowise connect-
    ed with the military service.”). In the Court’s view, the constitutional guarantees to
    trial by jury and indictment by grand jury in a capital case could not be denied by
    resort to a military commission. The Court held open the possibility that military
    commissions could be used to try citizens if martial law had properly been
    declared in the area, which could happen in times of invasion when the area in
    question was actually in the theater of military operations. As the Court put it, the
    “necessity must be actual and present; the invasion real, such as effectually closes
    the courts and deposes the civil administration.” 
    Id. at 127
    .
    We believe that the broad pronouncements in Milligan do not accurately reflect
    the requirements of the Constitution and that the case has properly been severely
    limited by the later decision in Quirin. As explained above, the Quirin Court set
    out a clear constitutional analysis under which it concluded that offenses triable by
    military commission under the laws of war were not within the commands of
    constitutional provisions guaranteeing certain procedures for criminal trials. As a
    result, the Court placed little or no significance on most of the factors cited in
    Milligan. The Court gave no weight to the fact that the civil courts were open
    where the German saboteurs had been captured. 
    317 U.S. at 23-24, 45
    . In addition,
    it rejected the idea that military jurisdiction would attach only if the defendants
    had entered the “theatre or zone of active military operations,” 
    id. at 38
    , and even
    declined to resolve arguments about whether one of the German saboteurs was a
    citizen (he claimed he had been a naturalized citizen, and therefore invoked
    Milligan) because it concluded that even if the defendant were a citizen, Milligan
    would not preclude his trial by military commission. The Court instead ruled that
    the decision in Milligan must be understood “as having particular reference to the
    facts” of that case. 
    Id. at 45
    . The particular facts that the Court found significant
    appear to have been that the saboteur in Quirin had engaged in acts that made him
    a belligerent, while Milligan, “not being a part of or associated with the armed
    forces of the enemy, was a non-belligerent, not subject to the law of war.” 
    Id.
     The
    Quirin Court thus repeatedly emphasized that citizenship would not protect a
    person “from the consequences of a belligerency which is unlawful.” 
    Id. at 37
    ; see
    also 
    id.
     (“Citizens who associate themselves with the military arm of the enemy
    government” are properly subject to trial by military commission). Citizens who
    engaged in belligerent acts, thus, could be tried by military commission. See also
    Colepaugh v. Looney, 
    235 F.2d 429
    , 432 (10th Cir. 1956) (“[T]he petitioner’s
    citizenship in the United States does not divest the Commission of jurisdiction
    over him, or confer upon him any constitutional rights not accorded any other
    belligerent under the laws of war.”). To explain the limitations on Milligan, two
    scenarios merit consideration here: (1) the use of military commissions to try U.S.
    citizens seized in the United States, and (2) the use of military commissions to try
    enemy aliens seized in the United States.
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    1. U.S. Citizens
    Quirin clearly establishes that U.S. citizens who act as belligerents may be tried
    by military commission for violations of the law of war. Nonetheless, as explained
    below, we caution that there may be some risk that there will be ambiguity
    concerning the application of Quirin and the distinction the Quirin Court drew
    between the case before it and Milligan.
    As outlined above, the analysis employed in Quirin exempted offenses against
    the laws of war from the scope of the constitutional guarantees for trial by jury and
    grand jury indictment for crimes. The Milligan Court had relied on the same
    constitutional guarantees to hold that a military commission lacked jurisdiction
    and suggested that the facts that Milligan was a U.S. citizen and not in military
    service particularly compelled preserving his right to jury trial. See 71 U.S. at 119
    (“[I]t is the birthright of every American citizen when charged with crime, to be
    tried and punished according to law.”); id. at 118 (emphasizing that Milligan was
    “not a resident of one of the rebellious states, or a prisoner of war, but a citizen of
    Indiana for twenty years past, and never in the military or naval service”). The
    logic of the rationale in Quirin, however, suggests that even a citizen could be
    tried by military commission if he were properly charged with any violation of the
    laws of war. It was the nature of the offense—an offense against the laws of war—
    that removed it from the scope of constitutional provisions for jury trial and grand
    jury indictment. Thus, the Court noted that it was not status as an alien or citizen
    that was critical for making the use of a military commission constitutionally
    permissible. Rather, “offenders were outside the constitutional guaranty of trial by
    jury, not because they were aliens but only because they had violated the law of
    war.” 
    317 U.S. at 44
    . In fact, Quirin made it explicit that U.S. citizenship alone
    does not suffice to invoke any limitation from Milligan on the jurisdiction of
    military commissions. The Court explained that “[c]itizens who associate them-
    selves with the military arm of the enemy government, and with its aid, guidance
    and direction enter this country bent on hostile acts are enemy belligerents” and
    may be tried under the laws of war. 
    Id. at 37-38
    . As a result, the Court declined
    even to resolve the claim that one of the eight German saboteurs was actually a
    U.S. citizen. See 
    id. at 45
    .
    We believe that, properly understood, the constitutional analysis in Quirin
    demonstrates that any person properly charged with a violation of the laws of war,
    regardless of citizenship or membership in the armed forces (of this country or
    another power), may be tried by military commission. The critical point for
    constitutional analysis is that a person properly charged with an offense against the
    laws of war has no right to an indictment or trial by jury under Article III or the
    Fifth and Sixth Amendments. Citizenship and membership in the military are not
    determinative factors for constitutional purposes. A person can properly be
    chargeable of an offense against the laws of war (such as spying), after all, without
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    being in the armed forces of a belligerent nation. The critical distinction is the
    nature of the offense. See United States v. Tiede, 
    86 F.R.D. 227
    , 254 (U.S. Ct.
    Berlin 1979) (“Quirin holds that whether an individual is entitled to a jury trial is
    determined by the nature of the crime with which he is charged.”). Offenses triable
    by the laws of war are not within the constitutional protections attached to criminal
    trials. As one district court recently held, “[u]nder Quirin, citizens and non-
    citizens alike—whether or not members of the military, or under its direction or
    control, may be subject to the jurisdiction of a military commission for violations
    of the law of war.” Mudd v. Caldera, 
    134 F. Supp. 2d 138
    , 145-46 (D.D.C. 2001);
    see also Colepaugh, 
    235 F.2d at 432
     (“[T]he petitioner’s citizenship in the United
    States does not divest the Commission of jurisdiction over him, or confer upon
    him any constitutional rights not accorded any other belligerent under the laws of
    war.”).
    The Supreme Court, however, did not go so far as to hold in Quirin that its
    constitutional rationale undermined Milligan entirely. Instead, the Court declined
    to “define with meticulous care the ultimate boundaries of the jurisdiction of
    military tribunals,” 
    317 U.S. at 45-46
    , and stated simply that the holding in
    Milligan should be construed as “having particular reference to the facts” in that
    case, 
    id. at 45
    . The facts that were particularly relevant appear to have been that
    the saboteur in Quirin who claimed citizenship had engaged in acts that made him
    a belligerent. Milligan, in contrast, was not in military service, and the Court
    stressed that he was not an “enemy belligerent” and, “not being a part of or
    associated with the armed forces of the enemy, was a non-belligerent, not subject
    to the laws of war.” 
    Id. at 45
    ; see also Milligan, 71 U.S. at 121-22 (emphasizing
    that Milligan was “a citizen in civil life, in nowise connected with the military
    service”). Thus, the line that the Court ultimately drew in Quirin to distinguish
    Milligan may be read to suggest that a citizen (not in the U.S. military) can be
    tried by military commission when he acts as a belligerent. See 
    317 U.S. at 37
    .
    That condition was most clearly met where citizens “associate themselves with the
    military arm of the enemy government.” 
    Id.
     The distinction suggests that Milligan
    can be explained on the basis that the actions charged in Milligan did not amount
    to acts of belligerency. Even under this approach to Quirin, we conclude that in
    the context of the current conflict, any actions by U.S. citizens that amount to
    hostile acts against the United States or it citizens (and certainly participation in
    biological attacks, the attacks of September 11, or similar attacks) would make a
    person a “belligerent” subject to trial by military commission under Quirin.
    We caution, however, that applying this standard may raise some ambiguities.
    The Milligan decision holds out at least the possibility that some charges that may
    be articulated under the law of war (such as the charge of giving aid and comfort
    to the enemy used in Milligan) may not, in some circumstances, amount to acts of
    belligerency triable by military commission. Exactly which acts place a person in
    the category of an “enemy belligerent” under Quirin thus may be a subject of
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    litigation. In addition, it might be argued that Quirin should be read as imposing a
    brighter-line test under which citizens are triable by military commission when
    they “associate themselves with the military arm of the enemy government.” 
    317 U.S. at 37
    . That standard, it could be claimed, is difficult to apply here because
    there are no organized armed forces of another belligerent nation facing the United
    States. For the reasons outlined above, we conclude that such an approach does not
    reflect the proper constitutional analysis and is not the proper reading of Quirin.
    Nonetheless, it raises a potential source of litigation risk.
    In short, although we conclude that a U.S. citizen found to have engaged in
    actions that are properly chargeable as offenses under the laws of war could
    constitutionally be tried by military commission in the United States, we caution
    that in some circumstances there could be litigation risks involved in establishing
    the exact application of the Supreme Court’s decisions.
    2. Enemy Aliens Seized in the United States
    Even if Milligan might raise litigation risks for the use of military commissions
    to try citizens, it should not raise the same difficulties for trying aliens charged
    with violations of the law of war. The Milligan Court repeatedly stressed the
    importance of citizenship in describing Milligan’s rights, and even though the
    Supreme Court has extended many constitutional protections to aliens within the
    United States, the distinction between the rights of citizens and aliens, especially
    in times of war, retains vitality today. As the Supreme Court explained in Johnson
    v. Eisentrager, 
    339 U.S. 763
    , 771 (1950), whatever protections may be extended
    to aliens in time of peace, “[i]t is war that exposes the relative vulnerability of the
    alien’s status.” 9 Since the Alien Enemy Act of 1798, 
    1 Stat. 577
     (codified as
    amended at 
    50 U.S.C. § 21
    ), it has been established that in times of declared war,
    the President may seize enemy aliens and intern or deport them. This “Executive
    power over enemy aliens, undelayed and unhampered by litigation, has been
    deemed, throughout our history, essential to war-time security.” Eisentrager, 
    339 U.S. at 774
    . As the Court in Eisentrager explained, since an alien citizen of an
    enemy nation may constitutionally be deprived of liberty by Executive action
    solely on the basis of his citizenship during time of war, “no reason is apparent
    why an alien enemy charged with having committed a crime should have greater
    9
    It is well established that during war enemy aliens are not entitled to the same constitutional rights
    as citizens. See Harisiades v. Shaughnessy, 
    342 U.S. 580
    , 587 (1952) (“The government’s power to
    terminate its hospitality [to aliens] has been asserted and sustained by this Court since the question first
    arose. War, of course, is the most usual occasion for extensive resort to the power.”); Ex parte
    Colonna, 
    314 U.S. 510
    , 511 (1942) (noting “the principle recognized by Congress and by this Court
    that war suspends the right of the enemy plaintiffs to prosecute actions in our courts.”); Cummings v.
    Deutsche Bank und Discontogesellschaft, 
    300 U.S. 115
    , 120 (1937) (“By exertion of the war power,
    and untrammeled by the due process or just compensation clause, Congress enacted laws directing
    seizure, use, and disposition of property in this country belonging to subjects of the enemy.”).
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    Legality of the Use of Military Commissions to Try Terrorists
    immunities from Executive action.” Id. at 784. As the Court concluded, the
    “Constitution does not confer a right of personal security or an immunity from
    military trial and punishment upon an alien enemy engaged in the hostile service
    of a government at war with the United States.” Id. at 785. Although there is no
    “government at war” with the United States in the current scenario, we believe that
    the same constitutional analysis would surely apply to aliens who have entered the
    United States to carry on a terrorist war at the behest of any foreign power.10
    There is some authority for the view that Milligan provides a broad standard
    guaranteeing the right to jury trial for both citizens and aliens for offenses that
    might be charged as crimes wherever the civil courts are open, as long as the
    offenses did not take place in the field of military operations or other peculiarly
    military territory. An opinion of the Attorney General issued at the end of World
    War I took this approach. In 1918, Attorney General Gregory relied on Milligan to
    advise President Wilson that a military commission would not properly have
    jurisdiction to try a Russian national seized at the Mexican border as he attempted
    to enter the United States to conduct acts of sabotage in the service of the German
    government. See Trial of Spies by Military Tribunals, 31 Op. Att’y Gen. 356, 357
    (1918) (the “1918 Opinion”). The opinion reasoned that the guarantee of a jury
    trial in criminal matters in Article III, Section 2 and the guarantees of the Fifth and
    Sixth Amendments should be read to constrain the use of military commissions. It
    concluded that “military tribunals, whether courts-martial or military commis-
    sions, cannot constitutionally be granted jurisdiction to try persons charged with
    acts or offences committed outside of the field of military operations or territory
    under martial law or other peculiarly military territory.” Id. at 361. Attorney
    General Gregory proceeded from that premise to conclude that the offense of
    spying—made triable by military commission—must be narrowly construed to
    involve actually passing through an enemy’s lines of defenses in an area of
    military operations. See id.; see also id. at 357 (emphasizing that defendant “had
    not entered any camp, fortification or other military premises of the United
    States”).11
    10
    We do not intend to address exhaustively here the Supreme Court’s decisions extending constitu-
    tional protections to aliens within the United States. We note, however, that the Court has explained
    such protections by stating that they extend to aliens who are lawfully in the United States and who
    have “developed substantial connections with this country,” United States v. Verdugo-Urquidez, 
    494 U.S. 259
    , 271 (1990), or as the Court recently put it, have “accepted some societal obligations,” 
    id. at 273
    . It seems unlikely, to say the least, that terrorists here on long-term missions to plot hostile acts
    could satisfy both of these conditions.
    11
    Specifically, the Attorney General addressed Article 82 of the Articles of War, which stated that
    “Any person who in time of war shall be found lurking or acting as a spy in or about any of the
    fortifications, posts, quarters, or encampments of any of the armies of the United States, or elsewhere,
    shall be tried by a general court-martial or by a military commission, and shall, on conviction thereof,
    suffer death.” 31 Op. Att’y Gen. at 358. He concluded that, because of constitutional constraints, the
    term “or elsewhere” could not be read to permit the trial by military commission of a defendant who
    was not seized in peculiarly military territory. 
    Id. at 361
    .
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    We believe that the 1918 Opinion is best understood as an attempt to articulate
    the current state of the law under then-existing Supreme Court decisions and that it
    does not reflect the best constitutional analysis. See, e.g., 
    id. at 359
     (stating that
    Milligan is “authoritative” concerning “application of these Constitutional
    provisions to the question of the scope of military jurisdiction”). Indeed, the
    rationale in the 1918 Opinion has been thoroughly undermined by the Court’s later
    decision in Quirin. First, in Quirin, the Court explained at length that Article III,
    Section 2 and the Fifth and Sixth Amendments do not apply to trials by military
    commission for offenses against the laws of war and were not intended to expand
    the right to jury trial that existed at common law at the time of the Founding. See
    
    317 U.S. at 39-43
    . Quirin thus rejected precisely the constitutional rationales upon
    which the Attorney General relied. Second, Attorney General Gregory relied on
    those constitutional rationales to expand Milligan to preclude the trial of aliens as
    well as citizens by military commission. He gave no particular rationale for
    extending those protections to aliens charged with hostile acts in time of war. In
    Quirin, moreover, the Court took the opposite route and concluded that, despite
    Milligan, even citizens were properly triable by military commission if they
    engaged in a belligerency unlawful under the laws of war. See 
    id. at 37-38, 45
    .
    Finally, Quirin can be read as rejecting even Attorney General Gregory’s spe-
    cific approach to requiring some particular nexus between the offense and
    “peculiarly military territory,” even for the particular offense of spying under the
    Articles of War. As noted above, to preserve the jurisdiction of civil courts, the
    1918 Opinion reached the specific conclusion that spying required the defendant to
    have crossed into “the field of military operations” or “other peculiarly military
    territory.” 31 Op. Att’y Gen. at 361; see also id. at 357 (noting that the accused
    “had not, so far as appears, been in Europe during the war, so had not come
    through the fighting lines or field of military operations”). The saboteurs in Quirin
    relied expressly on that opinion to argue that they had not crossed through any
    military lines, had not been seized in military territory, and thus should not be
    subject to trial before a military commission. See Cyrus Bernstein, The Saboteur
    Trial: A Case History, 
    11 Geo. Wash. L. Rev. 131
    , 152-54 (1943) (summarizing
    briefs before Supreme Court).12 In addressing charges under the same Article of
    War, the Quirin Court, without citing the 1918 Opinion, rejected these claims:
    “Nor are petitioners any the less belligerents if, as they argue, they have not
    actually committed or attempted to commit any act of depredation or entered the
    theatre or zone of active military operations.” 
    317 U.S. at 38
    ; see also 
    id. at 36-37
    (“[E]ntry upon our territory in time of war by enemy belligerents . . . for the
    12
    See also Eisentrager, 
    339 U.S. at 780
     (noting arguments in Quirin: “None of the places where
    they were acting, arrested, tried or imprisoned were, it was contended, in a zone of active military
    operations, were not under martial law or any other military control, and no circumstances justified
    transferring them from civil to military jurisdiction”).
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    Legality of the Use of Military Commissions to Try Terrorists
    purpose of destroying property used or useful in prosecuting the war, is a hostile
    and war-like act. It subjects those who participate in it without uniform to the
    punishment prescribed by the law of war for unlawful belligerents.”). The
    saboteurs in Quirin were seized in Chicago and New York (not “peculiarly
    military territory”) before they had completed any acts of sabotage, yet they were
    still chargeable as spies and subject to trial before a military commission.13 We
    believe that Quirin more accurately reflects the law. Milligan does not provide a
    substantial basis for precluding the trial of aliens by military commission for
    offenses against the laws of war even where the courts are open in the United
    States.14
    In any event, the particular circumstances addressed in the 1918 Opinion will
    likely have little relevance to the current crisis. First, many terrorists that come
    into U.S. custody will likely be apprehended overseas and will plainly be triable
    by military commission for violations of the laws of war under Johnson v.
    Eisentrager, 
    339 U.S. 763
     (1950). Constitutional concerns related to the use of
    military commissions within the United States thus will not arise. Second, the
    1918 Opinion addressed the unusual factual scenario of a defendant seized at the
    border “the moment he touched foot upon United States territory,” 31 Op. Att’y
    Gen. at 357, who had not completed any acts of espionage or sabotage, and who
    had never even approached a military base. It was in addressing that fact pattern
    under the particular offense of spying under Article 82 of the Articles of War that
    the Attorney General concluded that there must be some connection to the field of
    operations or particularly military territory. One year later, Attorney General
    Palmer made clear that the particular facts were critical as he concluded, upon
    learning different facts in the same case, that a military court properly did have
    jurisdiction to try the same defendant. See Trial of Spy by Court Martial, 40 Op.
    Att’y Gen. 561 (1919). He explained that, where the defendant had “crossed into
    our territory” and was arrested “about a mile distant from encampments where
    were stationed officers and men engaged in protecting the border against threat-
    ened invasion from the Mexican side,” 
    id.,
     a military court properly had jurisdic-
    tion.15 In the current situation, a scenario similar to that addressed in the 1918
    Opinion likely will not arise. Aliens apprehended in the United States would likely
    be charged in connection with completed hostile acts of unlawful belligerency or
    13
    In setting out the background of the case, the Court did note in a footnote that both of the beaches
    on which the saboteurs landed were within areas designated the “Eastern Sea Frontier” and the “Gulf
    Sea Frontier” by the military, see 
    317 U.S. at
    20 n.1, but it did not rely on these facts in its decision.
    14
    We also note that the 1918 opinion might have been influenced by the fact that it was issued on
    November 25, 1918, two weeks after the armistice with Germany had been signed.
    15
    Because Attorney General Palmer based his decision entirely on the changed facts (which
    brought the defendant within particularly military territory) and explicitly stated that “[t]his expression
    of my views should not be treated as overruling the opinion of my predecessor,” we believe it is still
    necessary to address the legal analysis of the 1918 Opinion, as we have above.
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    conspiracy related to those acts. There would be no credible argument that the
    definitions of the offenses under the laws of war should be construed narrowly so
    as not to include deliberate acts of mass murder that took approximately 3,000
    lives. *
    III. The President May Conclude That the Laws of Armed Conflict
    Apply to the Terrorist Attacks
    As explained above, 
    10 U.S.C. § 821
     sanctions the full uses of the military
    commission established by custom and Executive practice in the United States
    military. That practice, as noted above, has permitted military commissions to try
    all offenses against the laws of war. See, e.g., Quirin, 
    317 U.S. at 30
     (“Congress
    has incorporated by reference, as within the jurisdiction of military commissions,
    all offenses which are defined as such by the law of war.”) (emphasis added);
    Yamashita, 
    327 U.S. at 20
     (“Congress gave sanction . . . to any use of the military
    commission contemplated by the common law of war.”). The critical question for
    determining whether military commissions can properly be used here, therefore, is
    whether the terrorist attacks have created a situation to which the laws of war
    apply.16 That is, are the terrorist acts subject to the laws of war at all, or are they
    solely criminal matters to be treated under the municipal criminal law of the
    United States or a particular State?
    As outlined below, it would be difficult—or impossible—to articulate any
    precise multi-pronged legal “test” for determining whether a particular attack or
    set of circumstances constitutes “war” justifying application of the laws of war—
    or to use the modern terminology, whether it is an “armed conflict” justifying use
    of the “laws of armed conflict.” As the Supreme Court recognized long ago,
    determining whether a “war” exists depends largely on pragmatic considerations.
    As the Court put it in evaluating whether President Lincoln could properly invoke
    the laws of war by imposing a blockade on the southern states at the beginning of
    the Civil War, a conflict “becomes [a war] by its accidents—the number, power,
    and organization of the persons who originate and carry it on.” The Prize Cases,
    67 U.S. (2 Black) 635, 666 (1862). Precisely because it is a question that rests on
    pragmatic judgments that critically affect the national defense and vital matters of
    foreign policy, it is a determination that is properly left to the political branches,
    and particularly to the President. We explain in Part III.A below that the courts
    should defer to a presidential determination that the laws of armed conflict apply.
    *
    Editor’s Note: When this opinion was issued, this sentence referenced the taking of “over 4,500
    lives,” which was based on the information known at that time.
    16
    Because we conclude, as explained below, that the current conflict warrants application of the
    laws of war and thus justifies the use of military commissions under this standard, we need not and do
    not address whether the President’s inherent powers as Commander in Chief would extend further to
    permit the use of military commissions in other situations.
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    Legality of the Use of Military Commissions to Try Terrorists
    In Part III.B, we outline more specific principles that can be derived from
    precedents to demonstrate that the present attacks have created a set of circum-
    stances that properly merit invocation of the laws of war.17 The scale of these
    attacks, the number of deaths they have caused, and the massive military response
    they have demanded makes it virtually self-evident that the present situation can
    be treated as an armed conflict subject to the laws of armed conflict.
    A. Determining Whether War Exists Is a Question for the
    Political Branches
    Part of the reason it is difficult to articulate any broadly applicable “test” for
    determining whether a war exists is that the courts have quite properly concluded
    that that question (and thus the triggering of the laws of war) is one for the
    political branches. Early in the Nation’s history the Supreme Court recognized that
    Congress has authority to acknowledge a state of war, and that its decision to do
    so, whether formally and fully or partially and by degrees, is not subject to judicial
    question. See Talbot v. Seeman, 5 U.S. (1 Cranch) 1, 28 (1801) (“[C]ongress may
    authorize general hostilities, in which case the general laws of war apply to our
    situation; or partial hostilities, in which case the laws of war, so far as they
    actually apply to our situation, must be noticed.”); The Three Friends, 
    166 U.S. 1
    ,
    63 (1887) (“[I]t belongs to the political department to determine when belligerency
    shall be recognized, and its action must be accepted according to the terms and
    17
    We note that the Supreme Court’s decision in Quirin also demonstrates that, at least if those
    charged before a military commission are being held within the territorial United States, they would be
    able to file a petition for habeas corpus to have an Article III court test whether their cases fell within
    the jurisdiction of a military commission—that is, whether the offenses charged properly “set[] forth a
    violation of the law of war.” Quirin, 
    317 U.S. at 46
    ; see also 
    id. at 29
     (suggesting that some acts, even
    if considered violations of the laws of war in some countries or by some authorities, “would not be
    triable by military tribunal here . . . because they are not recognized by our courts as violations of the
    law of war”) (emphasis added); Yamashita, 
    327 U.S. at 9
     (“[T]he Executive branch of the Government
    could not, unless there was suspension of the writ, withdraw from the courts the duty and power to
    make such inquiry into the authority of the commission as may be made by habeas corpus.”);
    Colepaugh, 
    235 F.2d at 431
     (holding that on habeas review court may inquire into “applicability of the
    law of war to a particular case”). But cf. Johnson v. Eisentrager, 
    339 U.S. 763
    , 787-90 (1950) (holding
    that the writ of habeas corpus is not available to aliens held outside United States territory).
    It is unclear to what extent a court would inquire into the exact question here—namely, whether the
    current situation is a “war” permitting application of the laws of war. In Quirin, the existence of a war
    was definitively established by a congressional declaration of war, and the Court inquired solely into
    whether the specification of the charges against the saboteurs sufficiently “alleges violation of the law
    of war.” 
    317 U.S. at 36
    . In Yamashita, the Court addressed a question closer to the one here as it
    assessed a claim that military commissions could not be used after the cessation of hostilities—a claim
    it rejected. See 327 U.S. at 11-13. Although, as explained in text, determining whether the laws of war
    apply is properly a political question, it is possible that courts will not consider themselves bound by
    every determination of a political branch of the government that the laws of war apply. Thus, setting
    out the rationales that justify treating the current situation as “war” may be useful for this purpose as
    well.
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    intention expressed.”); see also, e.g., 3 Cumulative Digest of United States Prac-
    tice in International Law 1981-1988, at 3444 (1995) (“U.S. Practice”) (“The
    Courts have also treated the fundamental issue of whether an armed conflict is
    taking place for purposes of international or domestic law as a question to be
    decided by the political branches.”) (collecting authorities); Verano v. De Angelis
    Coal Co., 
    41 F. Supp. 954
    , 954 (M.D. Pa. 1941) (“‘It is the well-settled law that
    the existence of a condition of war must be determined by the political department
    of the government; that the courts take judicial notice of such determination and
    are bound thereby.’”) (quoting Hamilton v. McClaughry, 
    136 F. 445
    , 449 (C.C.D.
    Kan. 1905)); The Ambrose Light, 
    25 F. 408
    , 412 (S.D.N.Y. 1885) (where question
    of recognizing belligerent rights arises, courts “must follow the political and
    executive departments, and recognize only what those departments recognize”);
    United States v. One Hundred and Twenty-Nine Packages, 
    27 F. Cas. 284
    , 289
    (E.D. Mo. 1862) (“[T]he status of the country as to peace or war, is legally
    determined by the political and not the judicial department. When the decision is
    made the courts are concluded thereby, and bound to apply the legal rules which
    belong to that condition.”).
    We conclude that, even without any action by Congress to acknowledge a state
    of war, the President, in his constitutional role as Commander in Chief, and
    through his broad authority in the realm of foreign affairs, see, e.g., United States
    v. Curtiss-Wright Export Corp., 
    299 U.S. 304
    , 320 (1936), also has full authority
    to determine when the Nation has been thrust into a conflict that must be recog-
    nized as a war and treated under the laws of war. In The Prize Cases, the Supreme
    Court explained that it was up to the President to determine that a state of war
    existed that warranted according to the southern States the “character of belliger-
    ents.” 67 U.S. at 670. The judiciary, the Court noted, would be bound by his
    determinations in evaluating whether the laws of war applied to the blockade the
    President had instituted:
    Whether the President in fulfilling his duties, as Commander-in-
    chief, in suppressing an insurrection, has met with such armed hos-
    tile resistance, and a civil war of such alarming proportions as will
    compel him to accord to them the character of belligerents, is a ques-
    tion to be decided by him, and this Court must be governed by the
    decisions and acts of the political department of the Government to
    which this power was entrusted. . . . The proclamation of blockade is
    itself official and conclusive evidence to the Court that a state of war
    existed . . . .
    Id.; see also The Protector, 79 U.S. (12 Wall.) 700, 701-02 (1871) (relying on
    presidential proclamations to determine start and end dates for the Civil War);
    Salois v. United States, 
    33 Ct. Cl. 326
    , 333 (1898) (stating that if the government
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    Legality of the Use of Military Commissions to Try Terrorists
    had treated a band of Indians as at war, “the courts undoubtedly would be
    concluded by the executive action and be obliged to hold that the defendants were
    not in amity”).
    By making the President Commander in Chief of the armed forces, the Consti-
    tution must be understood to grant him the full authorities required for him to
    effectively defend the Nation in the event of an armed attack. Necessarily included
    among those powers must be the ability to determine whether persons responsible
    for an attack should be subject to punishment under the laws of war. We outlined
    above our conclusion that the President’s powers as Commander in Chief must
    include the authority to convene military commissions to enforce the laws of war.
    For largely the same reasons, the Commander in Chief’s power should include
    authority to determine when the armed forces are engaged in a conflict that merits
    application of the laws of war. Use of the laws of war, after all, can be a key
    component in a strategy for conducting and regulating a military campaign. The
    ability to apply the laws of war means the ability to punish transgressions by an
    enemy against those laws, and thereby to compel an enemy to abide by certain
    standards of conduct. There can be no basis for withdrawing from the Commander
    in Chief the authority to determine when the Nation has been subjected to such an
    attack as warrants the use of the laws of war to deal with the enemy.18
    B. The Terrorist Attacks Have Created a Situation That Can
    Properly Be Considered War
    Although the determination whether the current situation merits application of
    the laws of war is properly committed to the discretion of the President as
    Commander in Chief, there are some standards that the President could take into
    account. Under principles that can be gleaned both from American precedents and
    sources addressing the international laws of armed conflict, these factors indicate
    that the laws of armed conflict are properly applicable here. As the Supreme Court
    put it in evaluating whether President Lincoln could properly invoke the laws of
    war by imposing a blockade on the southern states at the beginning of the Civil
    War, a conflict “becomes [a war] by its accidents—the number, power, and
    organization of the persons who originate and carry it on.” The Prize Cases, 67
    U.S. at 666. Where an organized force is carrying on a campaign of violence that
    18
    It is a familiar principle that decisions made by the President in undertaking the defense of the
    Nation in his role as Commander in Chief are committed to his sole discretion and are not subject to
    review. See, e.g., Martin v. Mott, 
    25 U.S. 19
    , 30 (1827) (question whether circumstances require calling
    out the militia is committed to the discretion of the President: “[T]he authority to decide whether the
    exigency has arisen belongs exclusively to the President, and . . . his decision is conclusive upon all
    other persons.”); see also Stewart v. Kahn, 78 U.S. (1 Wall.) 493, 506 (1870) (“The measures to be
    taken in carrying on war . . . are not defined [in the Constitution]. The decision of all such questions
    rests wholly in the discretion of those to whom the substantial powers involved are confided by the
    Constitution.”).
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    reaches a sufficient level of intensity, it may be deemed an “armed conflict” by the
    President, thereby justifying application of the laws of armed conflict, including
    trials for the violation of those laws.19 As explained below, the terrorist attacks
    meet that test.
    1. American Precedents
    The political branches of the government, in whom the Constitution vests all of
    the war power, have long recognized that formal requirements are not the touch-
    stone for application of the laws of war.20 Actions based on that understanding,
    moreover, have repeatedly been upheld by the Supreme Court. Thus, for example,
    in the Quasi War with France, Congress exercised its power to authorize the
    seizure of French vessels, effectively using the rights of war, without declaring
    war. The Supreme Court recognized that Congress could take precisely such steps
    to use principles of the laws of war without any formal declaration. See, e.g., Bas
    v. Tingy, 4 U.S. (4 Dall.) 37, 43 (1800) (“Congress is empowered to declare a
    general war, or Congress may wage a limited war; limited in place, in objects, and
    in time.”);21 see also Existence of War with the Seminoles, 3 Op. Att’y Gen. 307
    (1838) (explaining that war may exist “although no formal declaration of war has
    been made” and can even exist “without the sanction of Congress”).22
    In addition, it is well established in Executive practice that war can exist (and
    the laws of war can be applied) even if the hostile parties are not two independent
    19
    Acknowledging that the laws of armed conflict may be applied to the present conflict does not
    mean in any way acknowledging the terrorists as legitimate combatants with any rights under the laws
    of armed conflict. To the contrary, based on their actions to date, the terrorists are all unlawful
    combatants stripped of any protection under the laws of armed conflict and are subject to trial for their
    violation.
    20
    Because most U.S. precedents addressing application of the laws of armed conflict date from
    World War II or before, they use the terminology of “law of war.” For consistency with the source
    material, we follow that terminology in this portion of the discussion.
    21
    See also U.S. Army Field Manual, The Law of Land Warfare, FM 27-10, ch. 1, ¶ 9 (July 1956, as
    updated) (“[A] declaration of war is not an essential condition to the application of this body of law.”).
    22
    Similarly, courts have recognized that the conflict in Vietnam was a war for purposes of applying
    the laws of war, even though Congress never declared war. See, e.g., United States v. Anderson, 
    38 C.M.R. 386
     (C.M.A. 1968). Accordingly, violations of the laws of war during Vietnam could be
    prosecuted as war crimes by military tribunals. In court-martial proceedings arising out of the incidents
    at My Lai, the Army Court of Military Review stated that “all charges could have been laid as war
    crimes.” United States v. Calley, 
    46 C.M.R. 1131
    , 1138 (A.C.M.R. 1973); see also 3 U.S. Practice
    at 3451. The court explained why the defendant was charged under the Uniform Code of Military
    Justice by citing paragraph 507(b) of chapter 8 of the U.S. Army Field Manual, The Law of Land
    Warfare, FM 27-10, which states that “the United States normally punishes war crimes as such only if
    they are committed by enemy nationals or by persons serving the interests of the enemy State.
    Violations of the laws of war committed by persons subject to the military law of the United States will
    usually constitute violations of the Uniform Code of Military Justice and, if so, will be prosecuted
    under that Code.” Calley, 46 C.M.R. at 1138.
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    Legality of the Use of Military Commissions to Try Terrorists
    sovereigns. Thus, at the outbreak of the Civil War, President Lincoln ordered a
    blockade of the southern states—an action that effectively invoked the rules of
    war—without any declaration of war and without any sovereign state as an enemy.
    In The Prize Cases, the Supreme Court addressed this action in the context of
    determining whether certain ships seized for attempting to run the blockade were
    lawfully captured as prizes. They would be lawful prizes only if the laws of war
    applied. In concluding that the prizes were lawful, the Court explained: “The
    parties belligerent in a public war are independent nations. But it is not necessary
    to constitute war, that both parties should be acknowledged as independent nations
    or sovereign States.” 67 U.S. at 666;23 accord United States v. Pacific R.R., 
    120 U.S. 227
    , 233 (1887).24 The mere fact that the terrorists are non-state actors,
    therefore, poses no bar to applying the laws of war here.
    American precedents also furnish a factual situation that is more closely analo-
    gous to the current attacks to the extent that they involve attacks by non-state
    actors that do not take place in the context of a rebellion or civil war. The analogy
    comes from the irregular warfare carried on in the Indian Wars on the western
    frontier during the nineteenth century. Indian “nations” were not independent,
    sovereign nations in the sense of classical international law, nor were Indian tribes
    rebels attempting to establish states. Cf. Cherokee Nation v. Georgia, 30 U.S.
    (5 Pet.) 1, 17 (1831) (Marshall, C.J.) (describing Indians tribes as “domestic
    dependent nations”). Nevertheless, the Supreme Court has explained that the
    conflicts between Indians and the United States in various circumstances were
    properly understood as “war.” Thus, in Montoya v. United States, 
    180 U.S. 261
    (1901), the Court (for purposes of a compensation statute passed by Congress)
    examined whether certain attacks were carried out by Indians from tribes “in
    amity” with the United States, which the Court approached by determining
    whether the Indians were at “war.” The Court explained that the critical factor was
    whether the Indians’ attacks were undertaken for private gain or as a general attack
    upon the United States: “If their hostile acts are directed against the Government
    or against all settlers with whom they come in contact, it is evidence of an act of
    war.” 
    Id. at 266
    ; see also 
    id.
     (critical factor is whether “their depredations are part
    23
    See also Pan American World Airways, Inc. v. Aetna Cas. & Sur. Co., 
    505 F.2d 989
    , 1013 (2d
    Cir. 1974) (“[W]ar can exist between quasi-sovereign entities.”).
    24
    Similarly, in Hamilton v. McClaughry, 
    136 F. 445
     (D. Kan. 1905), the court concluded that the
    Boxer Rebellion in China was a “war” sufficient to confer jurisdiction on a general court-martial to try
    a soldier for an offense “during time of war.” Even though the Boxers were not a government and could
    not be recognized as a sovereign nation, the court found that “there prevailed in China a condition of
    war” sufficient to justify a court-martial in applying punishments that apply during time of war. 
    Id. at 451
    ; see also Arce v. State, 
    202 S.W. 951
    , 951 (Tex. Crim. App. 1918) (holding that a “war” existed
    when a “force organized at Monterey [in Mexico] by the direction and under the authority of the
    Carranza de facto government”—an insurgent group—attacked U.S. troops sent into Mexico, and thus
    that prisoners seized in the engagement should not be tried in Texas courts for murder).
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    of a hostile demonstration against the Government or settlers in general, or are for
    the purpose of individual plunder”).
    Similarly, after the Modoc Indian War of 1873, the Attorney General opined
    that prisoners taken during the war who were accused of killing certain officers
    who had gone to parley under a flag of truce were subject to the laws of war and
    could be tried by a military commission. See The Modoc Indian Prisoners, 14 Op.
    Att’y Gen. 249 (1873). The Attorney General acknowledged that “[i]t is difficult
    to define exactly the relations of the Indian tribes to the United States,” but
    concluded that “as they frequently carry on organized and protracted wars, they
    may properly, as it seems to me, be held subject to those rules of warfare which
    make a negotiation for peace after hostilities possible, and which make perfidy like
    that in question punishable by military authority.” Id. at 253. Several Indian
    prisoners were tried by military commission and executed.
    The Attorney General reached a similar conclusion in 1871 in addressing the
    conduct of persons who had sold ammunition and rifles to hostile Indians. By
    statute, trading with Indians without a license was already prohibited. The
    Attorney General concluded, however, that trading with Indians “in open and
    notorious hostility to the United States at the time” constituted an offense under
    the Articles of War and could be tried by military commission. Unlawful Traffic
    with Indians, 13 Op. Att’y Gen. 470, 471 (1871). He explained that he was
    assuming “such a state of hostility on the part of the Indians as amounts to war,”
    and acknowledged that “[t]his state, in our peculiar relations with Indian tribes, is
    perhaps not susceptible of an exact definition.” Id. at 472. He concluded:
    It is not necessary to the existence of war that hostilities should have
    been formally proclaimed. When any Indian tribes are carrying on a
    system of attacks upon the property or persons, or both, of the set-
    tlers upon our frontiers, or of the travelers across our Territories, and
    the troops of the United States are engaged in repelling such attacks,
    this is war in such a sense as will justify the enforcement of the arti-
    cles of war against persons who are engaged in relieving the enemy
    with ammunition, etc.
    Id.
    It is true that many situations involving application of the laws of war in the
    past have involved conflicts between sovereigns or quasi-sovereign entities
    (including, for example, rebel movements attempting to establish governments).
    But that fact should not be understood as in any way precluding application of the
    laws of armed conflict to widespread terrorist violence. In the past, usually only a
    sovereign or quasi-sovereign entity attempting to establish itself as a government
    over a substantial territory could have the resources to mount and sustain a series
    of attacks of sufficient intensity to raise the question of “war” or “armed conflict.”
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    The terrorist network now facing the United States has found other means to
    finance its campaign while operating from the territory of several different nations
    at once. That change, however, cannot be considered to somehow exempt terrorist
    networks from the standards demanded by the laws of armed conflict and the
    punishments that would apply when the terrorists undertake violent attacks in
    violation of those laws. Simply by operating outside the confines of the traditional
    concepts of nation-states, terrorists cannot shield themselves from the prohibitions
    universally commanded by the laws of armed conflict and trial for violations of
    those laws. The examples from the Indian Wars above here provide an apt
    analogy. Indian tribes did not fit into the western European understanding of
    nation states—a difficulty that Attorneys General acknowledged. But that posed
    no bar to applying the laws of war when the United States was engaged in armed
    conflict with them.
    Moreover, there is nothing in the logic of the laws of armed conflict that in any
    way restricts them from applying to a campaign of hostilities carried on by a non-
    state actor with a trans-national reach. To the contrary, the logic behind the laws
    suggests that they apply here. Generally speaking, the laws are intended to confine
    within certain limits the brutality of armed conflict, which might otherwise go
    wholly unchecked. Cf. The Prize Cases, 67 U.S. at 667 (the laws of war “all tend
    to mitigate the cruelties and misery produced by the scourge of war”). The ability
    to punish violations of the laws of armed conflict is critical for deterring all
    foreign entities from undertaking any acts that violate those laws. If terrorists
    could somehow be exempt from being tried for violations of the laws of war
    simply because they do not need to rely upon a government—or a quasi-sovereign
    structure controlling territory—the purposes of the laws of war would be defeat-
    ed.25
    Under the precedents outlined above, the terrorist acts are plainly sufficient to
    warrant application of the laws of war. The attacks fit exactly the terms used in the
    25
    It also bears noting that the terrorists do share one significant characteristic with the case of rebels
    or insurgents. Rebels typically are attempting to establish a government to change the political order or
    enforce their political will on an existing government. Some definitions of war, indeed, describe it as
    the effort to impose political will by force. See, e.g., Carl von Clausewitz, On War 101 (A. Rapoport
    ed., Pelican Classics 1968) (1832) (“War therefore is an act of violence intended to compel our
    opponents to fulfil our will.”); id. at 119 (“War is . . . a continuation of political commerce, a carrying
    out of the same by other means.”). The terrorist attacks share this characteristic: they are designed to
    enforce a political will by arms. The attacks were directed against the government and people of the
    United States in an effort to force the United States to alter its foreign policies by the application of
    armed force. That is a classic description of the objectives of war. Thus, even though Usama bin Laden
    does not have any territory that he controls and cannot be said to operate as a quasi-sovereign entity, he
    was in effect acting in the same manner as a foreign power in attempting to enforce his political will on
    the United States by force of arms. While that aspect of the terrorist campaign is certainly not
    necessary for the attacks to be deemed an armed conflict, it does demonstrate that the current terrorist
    attacks share much in common with more familiar examples of armed hostilities subject to the laws of
    armed conflict.
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    cases above (which, as explained below, also closely parallel standards applied in
    international sources addressing the laws of armed conflict). The terrorists have
    engaged in a “system of attacks upon” the United States, that are part of a “hostile
    demonstration against the government [and people] in general.” 13 Op. Att’y Gen.
    at 472. Usama bin Laden has made it abundantly clear that he has called Muslims
    worldwide to a “jihad against the U.S. government, because the U.S. government
    is unjust, criminal and tyrannical.” CNN Interview with Osama bin Laden, Osama
    Bin Laden v. the U.S.: Edicts and Statements (Mar. 1997), available at http://www.
    pbs.org/wgbh/pages/frontline/shows/binladen/who/edicts.html (last visited July 26,
    2012); see also World Islamic Front Statement, Jihad Against Jews and Crusaders
    (Feb. 23, 1998), available at http://www.fas.org/irp/world/para/docs/980223-fatwa.
    htm (last visited July 26, 2012) (“The ruling to kill the Americans and their allies—
    civilians and military—is an individual duty for every Muslim who can do it in any
    country in which it is possible to do it . . . . We—with Allah’s help—call on every
    Muslim who believes in Allah and wishes to be rewarded to comply with Allah’s
    order to kill the Americans and plunder their money wherever and whenever they
    find it.”).
    In prosecuting this self-proclaimed war, the terrorists carried out a widespread
    and coordinated attack against military and civilian targets on September 11 that
    resulted in the loss of approximately 3,000 lives. That death toll surpasses that at
    Pearl Harbor, and rivals the toll at the battle of Antietam in 1862, one of the
    bloodiest engagements in the Civil War. The attacks, moreover, did not involve a
    single, isolated event. Rather, even if one looks solely to the events of September
    11, they involved the coordinated hijacking in different parts of the country of four
    separate aircraft that were then used as guided weapons. And if one looks beyond
    September 11, the attacks appear to be the culmination of a lengthy and sustained
    campaign that also includes the bombings of the World Trade Center in 1993, the
    Khobar Towers in Saudi Arabia in 1996, the U.S. embassies in Kenya and
    Tanzania in 1998, and the U.S.S. Cole in 2000. Especially when viewed as part of
    that continuing series of attacks, the most recent events plainly rise to the level of
    a systematic campaign of hostilities that justifies application of the laws of armed
    conflict.26
    26
    Indeed, compared to previous incidents found by the Executive Branch to trigger the application
    of the laws of armed conflict, Al Qaeda’s terrorism campaign falls well within United States practice.
    On December 3, 1983, two unarmed U.S. navy planes flying regular, routine reconnaissance flights
    were fired upon by hundreds of Syrian anti-aircraft guns and surface-to-air missiles. The United States
    responded to the attack the following day with airstrikes on the Syrian positions from which the gunfire
    and missiles had come. Two U.S. planes were shot down, and one officer was taken prisoner. The
    United States declared that the officer was entitled to prisoner of war status. According to a State
    Department press guidance, under the Geneva Conventions of 1949, “‘[a]rmed conflict’ includes any
    situation in which there is hostile action between the armed forces of two parties, regardless of the
    duration, intensity or scope of the fighting and irrespective of whether a state of war exists between the
    two parties.” 3 U.S. Practice at 3456-57.
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    In addition, the “troops of the United States are engaged in repelling such
    attacks” on a massive scale. 13 Op. Att’y Gen. at 472. Days after the attacks,
    Congress swiftly exercised its war powers to pass a joint resolution authorizing the
    President “to use all necessary and appropriate force against those nations,
    organizations, or persons he determines planned, authorized, committed, or aided
    the terrorist attacks that occurred on September 11, 2001.”27 The President has not
    only described the current situation as a “war,” he has also directed partial
    mobilization of the Ready Reserve (thus putting at his disposal one million
    members of the Ready Reserve and alerting 50,000 reservists so far), he has
    dispatched three carrier battle groups and dozens of additional aircraft to the
    region of Afghanistan, and he has launched air attacks against military targets in
    Afghanistan. In addition, fighter jets continue to patrol the skies over most major
    American cities. The level of the military response determined upon by the
    political branches of the government in itself, in our view, justifies the conclusion
    that the laws of war can be invoked.
    Finally, a further factor is virtually conclusive in itself in establishing that the
    attacks rise to the level of an armed conflict. In response to the attacks, NATO has
    already taken the unprecedented step of invoking Article 5 of the North Atlantic
    Treaty, which provides that an “armed attack against one or more of [the parties]
    shall be considered an attack against them all.” North Atlantic Treaty art. 5, Apr.
    4, 1949, 
    63 Stat. 2241
    , 2244, 34 U.N.T.S. 243, 246; see also Statement of NATO
    Secretary General Lord Robertson (Oct. 2, 2001), available at http://www.nato.int/
    docu/speech/2001/s011002a.htm (last visited May 17, 2012) (“it has now been
    determined that the attack against the United States on 11 September was directed
    from abroad and shall therefore be regarded as an action covered by Article 5 of
    the Washington Treaty”). Thus, under the mechanism provided in a treaty (which
    is part of the “supreme Law of the Land” under Article 6 of the Constitution, U.S.
    Const. art. VI, § 2), it has already been determined by a unanimous vote (including
    the vote of the United States) that the terrorist acts are an “armed attack” warrant-
    ing an international response. Indeed, at least one NATO member, Great Britain,
    has already participated with the United States in launching attacks in response to
    the terrorist acts, and others have pledged their participation for future military
    actions. Similarly, both the Organization of American States (“OAS”) and
    Australia and New Zealand have determined that parallel provisions in their
    mutual defense treaties applying to “armed attacks” have also been activated.28
    27
    Pub. L. No. 107-40, 
    115 Stat. 224
     (Sept. 14, 2001). Such a resolution was not necessary for the
    President to order a military response under his authority as Commander in Chief, but we note that the
    resolution was clearly an exercise of Congress’s war power. The resolution itself acknowledges in the
    preamble that “the President has authority under the Constitution to take action to deter and prevent
    acts of international terrorism against the United States.” 115 Stat. at 224.
    28
    See Security Treaty Between Australia, New Zealand and the United States of America art. 2,
    Sept. 1, 1951, 3 U.S.T. 3420, 3422, 131 U.N.T.S. 83, 86 (“ANZUS Pact”); White House, Fact Sheet,
    269
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    These actions already demonstrate recognition by other nations that the events of
    September 11 constituted “armed attacks” necessitating a military response.
    In short, the terrorist acts were not isolated acts of criminal violence; rather,
    they were an attack against the government and people of the United States. We
    believe that “this is war in such a sense as will justify the enforcement of the
    articles of war.” 13 Op. Att’y Gen. at 472.
    2. International Law Standards
    The precedents under American law outlined above are sufficient to establish
    conclusively that at least as of September 11, terrorist attacks on the United States
    had created a situation that would justify a conclusion that the laws of war
    properly apply. We realize that if a decision is made to use military commissions,
    it will also be important to justify American actions to our allies and others
    internationally. We therefore explain below that under sources of international law
    there are also ample authorities that could be cited to support a decision to apply
    the laws of war to the current conflict.
    There is, of course, no treaty to which the United States is a party that applies
    by its terms to the current conflict with a terrorist organization and that would
    subject terrorists to the laws of war—or as it is now more commonly referred to in
    international law, the “laws of armed conflict.” Our discussion, therefore, turns to
    some extent on principles reflective of “customary international law” concerning
    the breadth of the laws of armed conflict. Citation of such principles, however,
    should not be misunderstood to suggest that these principles are “law” in the sense
    that they bind the President as Commander in Chief. Rather, they are cited to
    demonstrate that, in the field of international law, certain principles have received
    sufficient recognition that they could be credibly cited as reflecting customary
    practice among nations. The President may choose to enforce these standards as a
    matter of policy (and may determine as a matter of policy to have the Armed
    Operation Enduring Freedom Overview: Campaign Against Terrorism Results (Oct. 1, 2001),
    available at http://2001-2009.state.gov/s/ct/rls/fs/2001/5194.htm (last visited Aug. 4, 2012) (noting that
    “Australia offered combat military forces and invoked Article IV of the ANZUS Treaty, declaring
    September 11 an attack on Australia”); Inter-American Treaty of Reciprocal Assistance art. 3(1), Sept.
    2, 1947, 
    62 Stat. 1681
    , 1700, 21 U.N.T.S. 77, 95 (“Rio Treaty”) (“an armed attack by any State against
    an American State shall be considered as an attack against all the American States”); Meeting of
    Consultation of Ministers of Foreign Affairs, Organization of American States, Terrorist Threat to the
    Americas (Sept. 21, 2001), available at http://www.oas.org/OASpage/crisis/RC.24e.htm (last visited
    May 22, 2012) (resolving “[t]hat these terrorist attacks against the United States of America are attacks
    against all American states and that in accordance with all the relevant provisions of the Inter-American
    Treaty of Reciprocal Assistance (Rio Treaty) and the principle of continental solidarity, all States
    Parties to the Rio Treaty shall provide effective reciprocal assistance to address such attacks and the
    threat of any similar attacks against any American state, and to maintain the peace and security of the
    continent”).
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    Forces of the United States adhere to similar standards), but they are not “law” that
    limits the President as Commander in Chief.
    Many of the same standards distilled from the American precedents outlined
    above are also reflected in international law sources addressing application of the
    laws of armed conflict. It bears emphasis at the outset that the term “law of war”
    used in 
    10 U.S.C. § 821
     refers to the same body of international law now usually
    referred to as the “laws of armed conflict.” See, e.g., Quirin, 
    317 U.S. at 30-31
    (explaining that the “law of war” incorporates the “common law of war” and
    looking to “universal agreement and practice” and “practice here and abroad” in
    determining scope of the laws of war, including army manuals from Germany and
    Britain); cf. International Criminal Tribunal for the Former Yugoslavia: Decision
    in Prosecutor v. Dusko Tadic, Oct. 2, 1995, 35 I.L.M. 32, 60 (1996) (“Prosecutor
    v. Tadic”) (noting changes in terminology). That refinement in terminology is not
    without significance, because it is designed to reflect more accurately the substan-
    tive reach of the international law restraints (and potential punishments) placed
    upon the conduct of armed conflicts. The laws of armed conflict are not restricted
    to situations of declared war—or even undeclared war—between nation states.
    Certain standards apply to any situation involving armed hostilities that have
    reached a sufficient level of intensity to be considered “armed conflict.” Under-
    standing the broader scope of this body of law is particularly important, because
    the fact that the terrorist attacks do not fit neatly into a classical concept of “war”
    may (improperly) pose an initial stumbling block hindering understanding of how
    the laws of armed conflict properly apply here.
    To begin with, the major conventions that set out international law standards
    governing international conflicts between states are not limited by the formal
    concept of “war.” Rather, each of the four Geneva Conventions of 1949, for
    example, applies “to all cases of declared war or of any other armed conflict which
    may arise between two or more of the High Contracting Parties.” See, e.g., Geneva
    Convention Relative to the Protection of Civilian Persons in Time of War art. 2,
    Aug. 12, 1949, 6 U.S.T. 3516, 3518, 75 U.N.T.S. 287, 288 (emphasis added); see
    also 3 U.S. Practice at 3453 (“[T]here need be neither a formal declaration of war
    nor a recognized state of war in order for the 1949 Geneva Conventions to come
    into effect. The occurrence of de facto hostilities is sufficient.”). Thus, even in the
    context of hostilities between nations, it is the existence of a set of facts—
    hostilities that amount to armed conflict—that triggers application of the provi-
    sions of the Geneva Conventions.
    It is true that the requirements in the Geneva Conventions apply by their terms
    solely to conflicts between states. Thus, those conventions are not triggered by a
    conflict solely with terrorists. But that does not mean that there are not principles
    of the laws of armed conflict that apply in other scenarios. The complete set of
    restrictions in those conventions is not the only source of the laws of armed
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    conflict that restrict the conduct of armed hostilities under international law.29 For
    example, common Article 3 of the Geneva Conventions was expressly designed to
    provide a form of safety net to establish minimal standards of humanitarian
    conduct that would govern in certain conflicts not covered by the Conventions.
    Thus, while the Geneva Conventions were designed to address international armed
    conflict, common Article 3 sets out some basic standards of humanitarian conduct
    that the parties are bound to apply “[i]n the case of armed conflict not of an
    international character” occurring within the territory of a Party. See e.g., Geneva
    Convention Relative to the Protection of Civilian Persons in Time of War art. 3,
    6 U.S.T. at 3518.30 Similarly, the 1996 Amended Protocol II to the 1980 U.N.
    Convention on Prohibitions or Restrictions on the use of Certain Conventional
    Weapons (to which the United States is a party) further elaborates some aspects of
    the laws of armed conflict that apply in such “internal” armed conflicts. S. Treaty
    Doc. No. 105-1, at 39 (1997). These provisions make it plain that the laws of
    armed conflict may apply to hostilities conducted by a non-state actor. They also
    illustrate that the trigger for applying these requirements is the crossing of a
    certain threshold of violence. The 1996 Amended Protocol II, for example,
    explains that it does not apply to “internal disturbances and tensions, such as riots,
    isolated and sporadic acts of violence and other acts of a similar nature,” because
    these are not “armed conflicts.” 1996 Protocol II, art. 1(2), id.31 Where there is
    some coordinated or organized campaign of violent acts that crosses that thresh-
    old, however, the factual situation warrants the application of the laws of armed
    conflict.
    The standards of common Article 3, moreover, are reflective of a minimal
    standard of conduct that some view as required in all armed conflicts. Cf. Hilaire
    McCoubrey, International Humanitarian Law: The Regulation of Armed Conflicts
    22 (1990) (“McCoubrey”) (“[I]t must be borne in mind that much of Conventional
    international humanitarian law forms a part of customary law . . . .”). The United
    29
    We assume for purposes of this discussion that it has not been established that the terrorist
    network carrying out the attacks was acting effectively as an agent for another nation. If the terrorists
    were acting as agents for another state, or were sponsored and supported by a state, there could be no
    question that the attacks constituted an international conflict to which the laws of armed conflict apply.
    30
    Common Article 3 extends only certain prohibitions under international law to covered internal
    conflicts. It does not extend prisoner of war status or immunity from domestic prosecution to rebels.
    See 3 U.S. Practice at 3448 (“Common Article 3 did not grant rebels the benefits of prisoner-of-war
    status and thus immunity from prosecution for combatant acts.”) (collecting authorities); id. at 3464
    (“Article III does not provide any immunity from prosecution to individuals for engaging in combatant
    acts.”).
    31
    This language is identical to that contained in the 1977 Protocol II to the Geneva Conventions.
    See Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection
    of Victims of Non-International Armed Conflicts art. 1(2), June 8, 1977, 1125 U.N.T.S. 609, 611. The
    United States has signed Protocol II, but is not a party to it. President Reagan forwarded the Protocol to
    the Senate for advice and consent to ratification on January 29, 1987, but it has not been ratified. See
    3 U.S. Practice at 3428-34.
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    States recognized that some such minimal principles could be enforced against
    enemies as long ago as 1945 when the International Military Tribunal at Nurem-
    berg applied standards of the Geneva and Hague Conventions to German conduct
    on the Eastern Front even though the Soviet Union had expressly denounced the
    Geneva Conventions before the war. See id. at 22-23.32 Since then, the United
    States has supported statements in the United Nations of minimal standards,
    reflective of the principles in common Article 3, that must be observed “by all
    governmental and other authorities responsible for action in armed conflict.” G.A.
    Res. 2444 (XXIII), ¶ 1, U.N. GAOR, 23d Sess., U.N. Doc. A/7433 (1968). This
    statement acknowledges that the laws of armed conflict can be applied to a broad
    range of situations involving non-state actors, for it addresses not only the actions
    of governments, but also “other authorities” responsible for “action in armed
    conflict.” The United States, in supporting this resolution, indicated that it
    “constituted a reaffirmation of existing international law.” U.N. GAOR, 3d
    Comm., 23d Sess., 1634th mtg. at 2, U.N. Doc. A/C.3/SR 1634 (1968); see also
    Letter for Sen. Edward Kennedy, Chairman of the Subcommittee on Refugees of
    the Committee on the Judiciary, from J. Fred Buzhardt, General Counsel, Depart-
    ment of Defense (Sept. 22, 1972), reprinted in 67 Am. J. Int’l L. 122, 124 (1973)
    (noting that Hague Conventions of 1907, Geneva Conventions of 1949, and G.A.
    Res. 2444 reflect existing international law).
    A final source worth noting as reflective of some current theories of the scope
    of the laws of armed conflict is the decision of the International Criminal Tribunal
    for the Former Yugoslavia. That Tribunal concluded that certain standards of
    conduct must constrain all forms of armed conflict of whatever nature. The
    Tribunal was faced with arguments that certain constraints applied solely to
    international armed conflict and that only the minimal standards of common
    Article 3 of the Geneva Conventions could apply to “internal” conflicts. While
    acknowledging that a fuller set of restrictions would apply to inter-state conflicts,
    the Tribunal concluded that at least some standards (both articulated by common
    Article 3 and dictated by customary law) would apply to any situation of armed
    conflict and explained that an “armed conflict” triggering application of these rules
    “exists whenever there is a resort to armed force between States or protracted
    armed violence between governmental authorities and organized armed groups or
    between such groups within a State.” Prosecutor v. Tadic, 35 I.L.M. at 54. The
    critical factor was whether hostilities had “exceed[ed] the intensity requirement,”
    id. at 55, sufficiently to be considered an “armed conflict.” As the decision of the
    32
    See also Quirin, 
    317 U.S. at 30, 35
     (explaining that by permitting trial of offenses against the
    “law of war,” Congress had incorporated by reference the “common law applied by military tribunals”
    and principles “recognized in practice both here and abroad”); FM 27-10 ch. 1, ¶ 4(b) (“Although some
    of the law of war has not been incorporated in any treaty or convention to which the United States is a
    party, this body of unwritten or customary law is firmly established by the custom of nations and well
    defined by recognized authorities on international law.”).
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    Tribunal suggests, the laws of armed conflict provide some minimal standards for
    any armed conflict, regardless of the particular characteristics of the conflict as
    one between states, or states and non-state actors. Thus, the Tribunal suggested
    that certain “[p]rinciples and rules of humanitarian law reflect ‘elementary
    considerations of humanity’ widely recognized as the mandatory minimum for
    conduct in armed conflicts of any kind.” 
    Id. at 70
     (emphasis added).
    It should be clear from the foregoing that there is sufficient authority in current
    sources under international law for the President to justify to the international
    community a decision that it will be the policy of the United States to apply the
    laws of armed conflict to terrorists in the current situation. The trigger for
    application of the laws does not depend on a formal concept of “war,” or on the
    political status of those engaged in the hostilities as sovereigns or states, but rather
    upon the fact of armed hostilities that have reached a certain level of intensity. If
    the attacks carried out by the terrorists meet the standards of initiating an “armed
    conflict,” therefore, the laws of armed conflict can be invoked. As one commenta-
    tor summarized, “[f]or the purposes of bringing into operation the rules regulating
    the conduct of hostilities, it no longer matters whether those hostilities are
    characterized as war. It is the factual concept of armed conflict rather than the
    technical concept of war which makes those rules applicable.” C. Greenwood, The
    Concept of War in Modern International Law, 36 Int’l & Comp. L.Q. 283, 304
    (1987); see also McCoubrey at 24 (“[War] has been deliberately abandoned as a
    definition of the circumstances of application of the jus in bello in general and of
    international humanitarian law in particular.”).33
    In light of this analysis, two mistaken concepts that might be raised as a basis
    for denying the application of the laws of armed conflict to the terrorist attacks are
    worth addressing and dismissing here. First, some might point to statements in
    older texts that “war” is a condition that exists only between states and claim that
    there can be no war (and hence no application of the laws of war) here. See, e.g.,
    2 L. Oppenheim, International Law: A Treatise § 54, at 202 (H. Lauterpacht ed.,
    7th ed. 1952) (“War is a contention between two or more States through their
    armed forces, for the purpose of overpowering each other and imposing such
    conditions of peace as the victor pleases.”); id. § 56, at 203 (“To be war, the
    contention must be between States.”).
    There are several flaws in such an argument. To the extent it relies on the syl-
    logism that, if a conflict is not between states it cannot be “war” and therefore the
    laws of war cannot apply, the conclusion is contradicted by the terms of the
    Geneva Conventions and consistent practice since World War II. As outlined
    33
    Based on rationales similar to those outlined here, multiple commentators have concluded that
    terrorist acts may properly trigger application of the laws of war. See, e.g., Crona & Richardson, 21
    Okla. City U.L. Rev. 349; Bradley Larschan, Legal Aspects to the Control of Transnational Terrorism:
    An Overview, 13 Ohio N.U.L. Rev. 117, 147-48 (1986); Should the Laws of War Apply to Terrorists?,
    79 Am. Soc’y Int’l L. Proc. 109, 109-11 (1985).
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    Legality of the Use of Military Commissions to Try Terrorists
    above, it has long been recognized that formal concepts of “war” do not constrain
    application of the laws of armed conflict and that non-state actors are properly
    bound by certain minimum standards of international law when they engage in
    armed hostilities. In addition, the syllogism itself distorts what was meant by the
    statement that war “must be between States.” In making that assertion, authors
    such as Oppenheim were suggesting only that for a conflict to be legitimate
    warfare it must be between states. It does not follow from that proposition that, if
    there is a conflict that amounts to warfare and non-state actors are involved, none
    of the restrictions on armed conflict applies at all. To the contrary, as Oppenheim
    recognized, quite a different conclusion follows—namely, that non-state actors
    who engage in warfare are engaged in a form of warfare that is illegitimate. See,
    e.g., Oppenheim § 254, at 574. In other words, they do not escape the laws of war
    because they are non-state actors. Instead, they are unlawful belligerents. Finally,
    the absolutist proposition that rules restraining the conduct of armed conflict apply
    only to a war between two states was not accepted even by authors such as
    Oppenheim. The proposition thus would not even accurately reflect the analysis
    applied in the discussions of the laws of war on which it purports to rely. Oppen-
    heim, for example, fully acknowledged that at least some aspects of the laws of
    war would properly apply in a conflict between a state and a non-state actor such
    as an insurgent group in a civil war. See id. § 59, at 209-10. Thus, even in older
    treatments of the subject, there is nothing talismanic about the involvement of
    states in a conflict for purposes of applying certain fundamental aspects of the
    laws of war.
    A related mistaken idea would be the suggestion that a trans-national attack by
    a non-state actor is somehow less susceptible to treatment under the law of war
    than such an attack carried on internally within a given state. It is true that the
    trans-national aspect of the attacks carried out by a non-state organization presents
    a somewhat novel situation. Articulations of the laws of armed conflict concerning
    non-state actors have been most fully developed in the context of internal conflicts
    in the form of rebellions or civil wars within a particular state. But, as explained
    above, there is nothing in the logic of the laws of armed conflict that would restrict
    its application in the case of a trans-border attack by a private armed band.
    The critical question for determining whether the laws of armed conflict apply
    here, therefore, is whether the terrorist attacks were a sufficiently organized and
    systematic set of violent actions that they crossed a sufficient level of intensity to
    be considered “armed conflict.” There can be no doubt that, whatever the “level of
    intensity” required to create an armed conflict, the gravity and scale of the
    violence inflicted on the United States on September 11 crossed that threshold. To
    use the words of the 1996 Amended Protocol II to the 1980 U.N. Convention on
    Conventional Weapons, which provides one guidepost for determining when an
    armed conflict exists, the attacks are not properly likened to mere “riots, isolated
    and sporadic acts of violence and other acts of a similar nature,” which do not
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    constitute “armed conflict.” Rather, as explained above, the terrorists have carried
    on a sustained campaign against the United States, culminating most recently with
    a devastating series of coordinated attacks resulting in a massive death toll.
    In addition, the United States has determined that it is necessary to respond to
    the attacks with military force. That decision is significant because one element
    often cited for determining whether a situation involving a non-state actor rises to
    the level of an “armed conflict” (for example, for purposes of common Article 3 of
    the Geneva Conventions) is whether a state responds with its regular military
    forces. The United States has urged this position. See 3 U.S. Practice § 2, at 3443;
    see also G.I.A.D. Draper, The Red Cross Conventions 15-16 (1958) (under
    common Article 3, “armed conflict” exists when the government is “obliged to
    have recourse to its regular military forces”). Here, this criterion is overwhelming-
    ly satisfied. As outlined above, the United States has found it necessary to respond
    with a massive use of military force. The current operations in Afghanistan and
    continuing preparations for a sustained campaign easily establish that the situation
    here involves an armed conflict for purposes of international law.
    Finally, as noted above, NATO’s decision to invoke Article 5 of the North
    Atlantic Treaty by deeming the terrorist acts an “armed attack” conclusively
    demonstrates that standards under international law for identifying an “armed
    conflict” have been satisfied here.
    IV. Under the Laws of War, the Terrorists Are Unlawful Combatants
    Subject to Trial and Punishment for Violations of the Laws of War
    We stress at the outset that determining that the terrorist attacks can be treated
    under the rubric of the “laws of war” does not mean that terrorists will receive the
    protections of the Geneva Conventions or the rights that the laws of war accord to
    lawful combatants. To the contrary, as the U.S. Army Field Manual, The Law of
    Land Warfare, makes clear, persons who do not comply with the conditions
    prescribed for recognition as lawful combatants (which include wearing a fixed
    insignia and bearing arms openly) are not entitled to status as prisoners of war and
    may be punished for hostile acts in violation of the laws of armed conflict.34 The
    Supreme Court made the same distinction clear in Quirin: “By universal agree-
    ment and practice the law of war draws a distinction between . . . those who are
    34
    FM 27-10, ch. 3, ¶ 80 (“Persons, such as guerillas and partisans, who take up arms and commit
    hostile acts without having complied with the conditions prescribed by the laws of war for recognition
    as belligerents . . . are, when captured by the injured party, not entitled to be treated as prisoners of war
    and may be tried and sentenced to execution or imprisonment.”); id. ¶ 81 (“Persons who, without
    having complied with the conditions prescribed by the laws of war for recognition as belligerents . . .
    commit hostile acts about or behind the lines of the enemy are not to be treated as prisoners of war and
    may be tried and sentenced to execution or imprisonment.”); id. ¶ 82 (“Persons in the foregoing
    categories who have attempted, committed, or conspired to commit hostile or belligerent acts are
    subject to the extreme penalty of death because of the danger inherent in their conduct.”).
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    lawful and unlawful combatants. . . . Unlawful combatants . . . are subject to trial
    and punishment by military tribunals for acts which render their belligerency
    unlawful.” 
    317 U.S. at 30-31
    .
    We indicate here, based on preliminary research, some offenses that might be
    charged under the laws of war to establish the jurisdiction of military commis-
    sions. The list here is representative only and is not intended by any means to be
    exhaustive.35
    As noted above, the terrorists involved in the attacks did not meet even the
    minimal conditions required to be recognized as lawful combatants. It is open to
    some doubt whether persons acting without authorization of a state could ever
    undertake hostile acts without violating the laws of war. But we need not reach
    that theory to conclude that the terrorists did not meet even the most basic
    requirements for complying with the laws of war as lawful combatants. They were
    not bearing arms openly and wearing fixed insignia. Thus, all of their hostile acts
    can be treated as violations of the laws of war. It is settled that any violation of the
    laws of war may be prosecuted as a “war crime.” The U.S. Army Field Manual,
    The Law of Land Warfare, provides that “[a]ny person, whether a member of the
    armed forces or a civilian, who commits an act which constitutes a crime under
    international law is responsible therefor and liable to punishment.” FM 27-10,
    ch. 8, ¶ 498. “The term ‘war crime’ is the technical expression for a violation of
    the law of war by any person or persons, military or civilian. Every violation of the
    laws of war is a war crime.” Id. ¶ 499.36 Specific offenses here could include
    violations of the rule prohibiting “[u]se of civilian clothing by troops to conceal
    their military character,” id. ¶ 504(g),37 the rule prohibiting “[f]iring on localities
    which are undefended and without military significance,” id. ¶ 504(d), and the rule
    prohibiting deliberate targeting of civilian populations.38
    35
    The substance of the laws of war, and of the offenses defined by the laws of war, can be deter-
    mined by looking to past American practice, especially the codification of the laws of war compiled by
    the United States Army in The Law of Land Warfare, and to sources of international law defining the
    laws of war, see, e.g., Quirin, 
    317 U.S. at 30
     (examining “universal agreement and practice” and
    sources from Great Britain and Germany, among other countries).
    36
    The Manual further states that “[a]s the international law of war is part of the law of the land of
    the United States, enemy personnel charged with war crimes are tried directly under international law
    without recourse to the statutes of the United States. However, directives declaratory of international
    law may be promulgated to assist such tribunals in the performance of their function.” Id. ¶ 505(e).
    37
    One precedent from a trial before a military commission in the Civil War provides a useful
    parallel to the terrorist attacks. In 1865 some confederate soldiers were tried for “violations of the laws
    and usages of civilized war” in that they “came on board a United States merchant steamer in the port
    of Panama ‘in the guise of peaceful passengers’ with the purpose of capturing the vessel and converting
    her into a Confederate cruiser.” Quirin, 
    317 U.S. at
    32 n.10.
    38
    See, e.g., FM 27-10, ch. 2, ¶ 25 (“[I]t is a generally recognized rule of international law that
    civilians must not be made the object of attack directed exclusively against them . . . .”); id. ¶ 39 (“The
    attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are
    undefended is prohibited.”). It is a commonly recognized principle under the customary laws of war
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    In addition, individuals can be prosecuted under the laws of armed conflict
    using standard theories of aiding and abetting and conspiracy. The U.S. Army
    Field Manual provides that “[c]onspiracy, direct incitement, and attempts to
    commit, as well as complicity in the commission of, crimes against peace, crimes
    against humanity, and war crimes are punishable.” FM 27-10, ch. 8, ¶ 500.
    Commanders can also be held responsible for war crimes committed either under
    their orders or by those under their command.39
    PATRICK F. PHILBIN
    Deputy Assistant Attorney General
    Office of Legal Counsel
    that civilian populations should not be the deliberate, sole target of attack. Thus, G.A. Res. 2444,
    supported by the United States, noted that “it is prohibited to launch attacks against the civilian
    population as such.” Id. ¶ 1(b); cf. Hersch Lauterpacht, The Problem of the Revision of the Law of War,
    29 Brit. Y.B. Int’l L. 360, 369 (1952) (“[I]t is in [the] prohibition, which is a clear rule of law, of
    intentional terrorization—or destruction—of the civilian population as an avowed or obvious object of
    attack that lies the last vestige of the claim that war can be legally regulated at all. Without that
    irreducible principle of restraint there is no limit to the licence and depravity of force.”).
    39
    See, e.g., The Law of Land Warfare, FM 27-10, ch. 8, ¶ 501 (“In some cases, military command-
    ers may be responsible for war crimes committed by subordinate members of the armed forces, or other
    persons subject to their control. . . . Such a responsibility arises directly when the acts in question have
    been committed in pursuance of an order of the commander concerned. The commander is also
    responsible if he has actual knowledge, or should have knowledge, through reports received by him or
    through other means, that troops or other persons subject to his control are about to commit or have
    committed a war crime and he fails to take the necessary and reasonable steps to insure compliance
    with the laws of war or to punish violators thereof.”); see also Yamashita, 
    327 U.S. at 14-18
    .
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