United States v. Mumuni ( 2019 )


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  • 18‐1604‐cr
    United States v. Mumuni
    In the
    United States Court of Appeals
    for the Second Circuit
    AUGUST TERM 2018
    No. 18‐1604‐cr
    UNITED STATES OF AMERICA,
    Appellant,
    v.
    FAREED MUMUNI,
    Defendant‐Appellee,
    MUNTHER OMAR SALEH, ALSO KNOWN AS ABU OMAR AL‐RAMLI, ALSO
    KNOWN AS ABU OMAR AR‐RAMLI,
    Defendant.
    On Appeal from the United States District Court
    for the Eastern District of New York
    SUBMITTED: MAY 17, 2019
    DECIDED: DECEMBER 27, 2019
    Before: WALKER, CABRANES, and HALL, Circuit Judges.
    In this terrorism case, the Government appeals the substantive
    reasonableness of the sentence imposed on Defendant‐Appellee
    Fareed Mumuni (“Mumuni”). He was convicted of, inter alia,
    conspiring to provide material support to the Islamic State of Iraq and
    al‐Sham (“ISIS”) and attempting to murder a federal agent in the name
    of ISIS. His advisory sentence under the United States Sentencing
    Guidelines (“Guidelines” or “U.S.S.G.”) was 85 years’ imprisonment.
    The sole question on appeal is whether the United States District Court
    for the Eastern District of New York (Margo K. Brodie, Judge) erred—
    or “abused its discretion”—by imposing a 17‐year sentence, which
    constitutes an 80% downward variance from Mumuni’s advisory
    Guidelines range. We conclude that it did. Accordingly, we REMAND
    the cause for resentencing consistent with this opinion.
    Judge Hall concurs in part and dissents in part in a separate
    opinion.
    Emily Berger, Alexander A. Solomon,
    Douglas M. Pravda, and Samuel P. Nitze,
    Assistant United States Attorneys, for
    Richard P. Donoghue, United States
    Attorney for the Eastern District of New
    York, Brooklyn, NY, for Appellant.
    2
    Anthony L. Ricco, Steven Z. Legon, and
    Kenneth J. Montgomery, New York, NY, for
    Defendant‐Appellee.
    JOSÉ A. CABRANES, Circuit Judge:
    In this terrorism case, the Government appeals the substantive
    reasonableness of the sentence imposed on Defendant‐Appellee
    Fareed Mumuni (“Mumuni”). He was convicted of, inter alia,
    conspiring to provide material support to the Islamic State of Iraq
    and al‐Sham (“ISIS”) and attempting to murder a federal agent in the
    name of ISIS. His advisory sentence under the United States
    Sentencing Guidelines (“Guidelines” or “U.S.S.G.”) was 85 years’
    imprisonment. The sole question on appeal is whether the United
    States District Court for the Eastern District of New York (Margo K.
    Brodie, Judge) erred—or “abused its discretion”—by imposing a 17‐
    year sentence, which constitutes an 80% downward variance from
    the advisory Guidelines range. We conclude that it did. Accordingly,
    we REMAND the cause for resentencing consistent with this
    opinion.
    3
    I. BACKGROUND1
    Mumuni is an American‐born citizen who pledged allegiance
    to ISIS and pleaded guilty, without a plea agreement, to: (1)
    conspiring to provide material support—including services and
    himself—to a foreign terrorist organization, to wit ISIS, in violation of
    18 U.S.C. § 2339B; (2) attempting to provide material support to ISIS,
    in violation of 18 U.S.C. § 2339B; (3) conspiring to assault federal
    officers, in violation of 
    18 U.S.C. § 371
    ; (4) attempted murder of
    federal officers, in violation of 
    18 U.S.C. § 1114
    ; and (5) assault of a
    federal officer with a deadly or dangerous weapon, in violation of 
    18 U.S.C. § 111
    . Mumuni was sentenced principally to a 204‐month (17‐
    year) term of imprisonment and 10 years of supervised release.
    Mumuni’s statutorily restricted advisory Guidelines2 sentence was
    1,020 months, or 85 years. The Government appeals only the
    substantive reasonableness of Mumuni’s sentence.
    We conclude that Mumuni’s sentence is substantively
    unreasonable for three reasons. First, the District Court clearly erred
    1These facts are drawn from the record before the District Court, including
    sentencing materials in connection with Mumuni’s co‐defendant, Munther Omar
    Saleh.
    2  See U.S. SENTENCING GUIDELINES MANUAL (“U.S.S.G.”) § 5G1.2(b) (“[T]he
    court shall determine the total punishment and shall impose that total
    punishment on each such count, except to the extent otherwise required by law.”);
    id. cmt. n.3(B) (“The defendant’s guideline range on the Sentencing Table may be
    affected or restricted by a statutorily authorized maximum sentence . . . .”).
    4
    in its assessment of the evidence at sentencing. Specifically, it
    impermissibly second‐guessed—after accepting Mumuni’s guilty
    plea—whether Mumuni actually intended to kill his victim and
    whether the eight‐inch kitchen knife3 he wielded during his attack on
    law enforcement constituted a deadly or dangerous weapon. Second,
    the District Court imposed a disproportionately lenient sentence on
    Mumuni compared to his co‐defendant, who, unlike Mumuni, did
    not physically attack a federal officer. Finally, the District Court
    placed mitigating weight on certain factors that could not bear the
    weight the District Court assigned to them.
    *       *      *
    Mumuni’s offense conduct begins with his considerable efforts
    to provide material support to ISIS.4 Between approximately
    February and June 2015, Mumuni conspired with Munther Omar
    Saleh (“Saleh”)5—a self‐proclaimed “full‐fledged” member of ISIS
    3   The knife’s blade was 200 millimeters, which is approximately 7.87
    inches.
    The United States Department of State has designated ISIS a foreign
    4
    terrorist organization under the name “Islamic State of Iraq and the Levant”
    (“ISIL”). See Bureau of Counterterrorism & Countering Violent Extremism, Foreign
    Terrorist Organizations, U.S. DEP’T OF STATE, https://www.state.gov/foreign‐
    terrorist‐organizations/. This opinion uses the acronyms “ISIS” and “ISIL”
    interchangeably.
    Mumuni met Saleh through the Islamic Society at the College of Staten
    5
    Island, where he was pursuing a degree in social work.
    5
    with a “radicalizing gift”6—and others, to provide material support
    to ISIS. Mumuni and Saleh helped facilitate the travel of co‐
    conspirator Nader Saadeh (“Saadeh”) to Syria to join ISIS.
    Specifically, both Mumuni and Saleh accompanied Saadeh on a
    shopping trip to purchase items that would be useful in ISIS‐
    controlled territories, such as hiking boots and a compass. 7 Mumuni
    also made plans to personally travel to Syria to join ISIS and wage
    jihad. Mumuni admitted that he and Saleh had been working to raise
    money for their travels to join ISIS, and that he had begun
    researching flights from New York to Turkey.
    Beyond his efforts to facilitate travel to Syria, Mumuni also
    conspired with Saleh and others to conduct a domestic terrorist
    attack against law enforcement officers. Indeed, in a post‐arrest
    statement to agents from the Federal Bureau of Investigation (“FBI”),
    Mumuni confirmed no less than four times that he planned to attack
    law enforcement were they to ever approach him or prevent him
    from traveling to Syria. Mumuni was offered a pressure‐cooker bomb
    from Saleh for his attack. When Mumuni asked Saleh whether it
    would be permissible from a religious standpoint to die during his
    attack on law enforcement, Saleh contacted Junaid Hussain
    6   GA 245.
    7 Saadeh ultimately boarded a flight at John F. Kennedy International
    Airport to Jordan; upon landing, he was intercepted and apprehended by
    Jordanian authorities.
    6
    (“Hussain”), a notorious Syria‐based ISIS attack facilitator.8 Hussain
    expressly authorized Mumuni’s suicide attack:
    Saleh: Akhi [brother] help us out, i have an
    akh [brother] who is planning on hitting a
    black car cop with a pressure cooker, the
    black car keeps following him, and he wants
    to avenge our akhs [brothers] who have
    been raided and blocked from hijrah
    [migration].
    Is it permissible for him to do the attack and
    die purposely in the process?9
    Hussain: Yes akhi [brother] he can do an
    isthishadi [martyrdom] operation on the
    8See Margaret Coker, et al., Hacker Killed by Drone was Islamic State’s ‘Secret
    Weapon,’ WALL ST. J. (Aug. 27, 2015), https://www.wsj.com/articles/hacker‐killed‐
    by‐drone‐was‐secret‐weapon‐1440718560 (“U.S. officials began to view Mr.
    Hussain as a top threat because he was on the leading edge of Islamic State efforts
    to recruit in the U.S.”); see also The American Exception: Terrorism Prosecutions in the United
    States—The ISIS Cases (March 2014 – August 2017), CTR. ON NAT’L SEC. AT FORDHAM
    LAW 29, 32–33 (Sept. 2017) https://news.law.fordham.edu/wp‐
    content/uploads/2017/09/TheAmericanException9‐17.pdf (describing various
    connections between Hussain and other ISIS terrorists and terrorism plots).
    9   GA 250.
    7
    police akhi [brother] . . . If he has no other
    way to fight them he can do it.10
    Saleh and Mumuni would regularly contact each other with
    ideas for an attack. For example, on June 2, 2015, Saleh instructed
    Mumuni that the best option for attacking law enforcement was to
    use a bomb and fight afterwards. When Mumuni asked for further
    guidance, Saleh wrote that Mumuni should first detonate a bomb,
    run over the officers with a vehicle, seize their weapons, and then use
    the weapons to shoot at other victims.
    On June 12, 2015, Saleh texted Mumuni: “I decided to tell my
    parents ‘i will be gone in much less than a year, in sha Allah, you
    have two choices, either you let me go to Darul Islam [ISIS‐controlled
    territory] or you watch me kill nonMuslims [sic] here.[’]”11 Mumuni
    replied: “May Allah make it easy for you.”12 That night, Saleh
    executed an attack against law enforcement.
    Saleh and co‐conspirator Imran Rabbani (“Rabbani”) had been
    driving in an SUV the evening of June 12 when they noticed an
    unmarked vehicle following them. The men performed several anti‐
    surveillance maneuvers to evade the unmarked vehicle, including
    driving at high speeds through a parking lot with their lights turned
    10   Id.
    11   Mumuni Presentence Investigation Report (“PSR”) ¶ 19.
    12   Id.
    8
    off and running stop signs. At approximately 4 a.m. on June 13, Saleh
    and Rabbani stopped their vehicle at a red light at 20th Avenue, on
    an overpass above the Whitestone Expressway in Queens. Saleh and
    Rabbani exited their SUV and began walking toward the unmarked
    vehicle. As Saleh approached the unmarked vehicle, he placed an
    unopened folding knife from his hand into his pocket. Before Saleh
    and Rabbani reached the unmarked vehicle, they decided to turn
    around and re‐enter their SUV. Moments later, Saleh and Rabbani
    again exited the SUV and began charging toward the unmarked
    vehicle. The FBI agent in the unmarked vehicle had to quickly
    reverse off the highway overpass into oncoming traffic in order to
    evade Saleh and Rabbani’s attack.
    When backup officers arrived, they arrested Saleh and Rabbani
    and discovered a folding knife in the SUV and a Smith & Wesson
    tactical folding knife in Rabbani’s waistband. Rabbani’s knife had
    been equipped with a built‐in window breaker, which would have
    allowed Saleh and Rabbani to gain immediate access to the FBI
    vehicle.
    In a post‐arrest interview, Saleh stated that he had pledged
    allegiance to, and was a “full‐fledged” member of, ISIS.13 In addition,
    he characterized Mumuni as another ISIS supporter and confirmed
    that Mumuni planned to travel to the Islamic State‐held territory.
    Saleh also informed the interviewing agents that Mumuni had
    13   Id. ¶ 17.
    9
    expressed an intent to attack law enforcement officers who had been
    surveilling him.
    Mumuni’s June 17, 2015 Attack on Law Enforcement
    Two days after Saleh’s attack, the Government obtained a
    search warrant for Mumuni’s cellular phone and residence on Staten
    Island. On June 17, 2015, FBI agents went to Mumuni’s residence to
    execute the search warrant. The agents knocked on the front door
    and announced themselves as members of law enforcement.
    Mumuni’s mother and sister opened the door and granted the
    officers permission to enter the premises.
    Mumuni, aware that law enforcement officers had entered his
    home,14 retrieved an eight‐inch kitchen knife from his bedroom15 and
    descended the stairs. With the knife concealed behind his back,
    Mumuni—pursuant to the agents’ instructions—entered the living
    room and walked toward the couch. Suddenly, he began charging
    toward FBI Special Agent Kevin Coughlin (“Agent Coughlin”). It
    14As Mumuni explained after his arrest, he knew that law enforcement
    was at his door “‘cause no one bangs at the door like that.” See June 17, 2015 Post‐
    Arrest Statement Transcript (“June 17, 2015 Transcript”) at 83.
    15 As Mumuni later admitted to investigating agents, he began keeping one
    knife under his pillow and one in his mother’s car “in case [officers tried] to stop
    me.” Id. at 64.
    10
    wasn’t until he was within “arm’s length”16 that Mumuni revealed
    his knife and began stabbing the unarmed Agent Coughlin. During
    the ensuing tussle, as other agents rushed to Agent Coughlin’s aid,
    Mumuni attempted to reach for the trigger of another agent’s M4
    carbine assault rifle.17
    Fortunately, prior to entering Mumuni’s home, Agent
    Coughlin made a “last‐minute decision” to wear an armored SWAT
    vest.18 As the Government’s edged‐weapons expert explained,
    however, SWAT vests are designed to stop bullets, not blades, and
    do not typically stop thrusts or stabbing attacks. What ultimately
    shielded Agent Coughlin from Mumuni’s repeated stabs was the
    metal magazine carrier inside his vest. Indeed, photographs taken
    after the attack show Agent Coughlin’s metal magazine carrier with
    three distinct indentations and an eight‐inch kitchen knife with a
    missing tip.
    16   GA 204.
    17 While Mumuni disputes this account, the District Court declined to
    strike this text from the PSR, opting instead to insert the following objections:
    “Fareed Mumuni asserts that upon lunging at the first agent, he was taken down
    and immediately subdued by the agents. He denies any allegation that he reached
    for an agent’s firearm and attempted to pull the trigger,” GA 185, and “Fareed
    Mumuni acknowledges that he lunged at a law enforcement officer with a single
    kitchen knife, however, he denies repeatedly stabbing anyone,” id. 186. The
    District Court did not appear to accept or reject either account of the attack. It did,
    however, decline to consider Mumuni’s argument that the facts and
    circumstances did not support the use of the first‐degree murder guideline. Id.
    18   Id. at 203.
    11
    After subduing and arresting Mumuni, the agents received
    consent from Mumuni’s mother to search her car, where they
    recovered another large kitchen knife hidden in a duffel bag.
    Mumuni pleaded guilty on February 9, 2017, to conspiring and
    attempting to provide material support to ISIS,19 conspiring to attack
    federal officers,20 assaulting a federal officer with a dangerous or
    deadly weapon,21 and attempting to murder a federal officer.22 The
    District Court accepted the guilty plea after affirming that it had been
    entered knowingly and voluntarily and that it was “supported by an
    independent basis in fact containing the essential elements of the
    offenses.”23
    Mumuni’s Sentencing
    Mumuni’s Sentencing Guidelines calculation, as reported in his
    Presentence Investigation Report (“PSR”) and adopted by the District
    19   18 U.S.C. § 2339B.
    20   Id. § 371.
    21   Id. § 111(a)(1), (b).
    22   Id. § 1114(3).
    23   GA 63.
    12
    Court,24 reflected a total offense level of 43 and a criminal history
    category of VI, resulting in an advisory Guidelines sentence of life
    imprisonment. Because life imprisonment exceeded the statutorily
    authorized maximum sentence of 1,020 months (85 years), the
    statutorily authorized maximum sentence of 1,020 months (85 years)
    became the Guidelines sentence.25
    At sentencing, the Government sought the Guidelines sentence
    of 1,020 months (85 years). It focused on the exceptionally serious
    nature of Mumuni’s conduct, including the fact that when Mumuni
    attempted to kill Agent Coughlin, he was engaged in an act of
    terrorism for which he had received advance authorization from
    Junaid Hussain, a Syria‐based ISIS operative. It also compared
    Mumuni’s case to those of similarly‐situated terrorism defendants
    who, like Mumuni and Saleh, had been recruited by Hussain to
    commit domestic terror attacks in the United States.26 Finally, the
    24 The District Court did not identify any errors in the PSR’s Guidelines
    calculations. It did, however, correct errors, not relevant here, in the PSR’s
    supervised release calculations.
    25 See U.S.S.G. § 5G1.2(b) (“[T]he court shall determine the total
    punishment and shall impose that total punishment on each such count, except to
    the extent otherwise required by law.”); id. cmt. n.3(B) (“The defendant’s
    guideline range on the Sentencing Table may be affected or restricted by a
    statutorily authorized maximum sentence . . . .”).
    26 The Government focused on two cases in particular: the David Wright
    (“Wright”) case and the Justin Sullivan (“Sullivan”) case. In 2017, a district court
    in the District of Massachusetts sentenced Wright to 28 years, following a trial, for
    encouraging his co‐conspirator, Usaamah Rahim (“Rahim”), to “go after” the
    13
    Government presented testimony from Agent Coughlin, who
    described in vivid detail the premeditated and extremely violent
    nature of Mumuni’s attack.27
    By contrast, Mumuni‘s counsel sought a sentence at variance
    with the Guidelines. He highlighted several mitigating factors,
    including Mumuni’s young age at the time of his arrest (21 years
    old), his lack of criminal history, the letters of support he had
    “boys in blue.” GA 260. Rahim had received instructions from Hussain to behead
    Pamela Geller, the organizer of the Prophet Muhammad contest in Garland,
    Texas. Rahim was killed after lunging towards police officers and FBI agents with
    a large fighting knife and refusing to drop his weapon. Another co‐conspirator,
    Nicholas Rovinski (“Rovinski”), was sentenced to 15 years’ imprisonment—just
    two years fewer than Mumuni—after pleading guilty and testifying as a
    cooperating witness at Wright’s trial.
    Similarly, in 2015 in the Western District of North Carolina, Sullivan was
    recruited by Hussain to conduct attacks on behalf of ISIS. Sullivan agreed to buy
    an AR‐15 rifle at a gun show and to shoot to death as many people as possible at a
    club or concert in North Carolina. After a silencer Sullivan ordered was delivered
    to his house and opened by his parents, Sullivan asked an undercover FBI agent
    to kill his parents. When agents subsequently searched Sullivan’s house, they
    discovered a .22 Marlin rifle loaded with 14 rounds and a travel bag containing a
    black ski mask and lock picking tools. Unlike Mumuni, Sullivan never actually
    conducted a terror attack. Nevertheless, he was sentenced to life imprisonment.
    27 See, e.g., GA at 204 (“I also think it’s important to point out that when
    Mr. Mumuni came down those stairs that day, that he came down those stairs
    with the intent of trying to kill one of us. And I say that because it’s not like he
    grabbed that knife from the kitchen on his way down. He had that knife with him
    in his room when he came out and he concealed it until the last possible minute.
    He did not walk down those stairs [waving] that knife around, because if he had,
    we would have shot him before he got to the bottom of the stairs.”).
    14
    received from friends and family members, and the fact that, unlike
    Saleh, he was not a leader and did not recruit anyone to join ISIS.
    Mumuni’s counsel further noted the “absence of physical injury and
    damage to property or people,”28 and repeatedly characterized
    Mumuni’s attack as an attempt to commit “suicide by cop,”29 i.e., an
    attempt to provoke a lethal response from law enforcement.
    The District Court ultimately sentenced Mumuni to a
    cumulative 204‐month term of incarceration—80% below the
    advisory Guidelines sentence. Specifically, Mumuni received
    concurrent 120‐month terms on the two material support charges;
    concurrent 60‐month terms on the two assault charges; and a
    concurrent 204‐month term of imprisonment for the attempted
    murder charge. In effect, Mumuni received only 84 months (7 years)
    for attempting to murder Agent Coughlin.
    28   Id. at 190.
    29 Dist. Ct. Dkt. No. 153 at 16–17 (“[U]pon [law enforcement’s] entry, a
    radicalized Fareed Mumuni lunged toward one of the agents with a kitchen knife
    in hand, in an unsuccessful attempt to commit suicide by cop. In so doing, Fareed
    Mumuni committed the offense of attempted murder of a federal agent.”); see also
    GA 192–93 (“What did [Mumuni] think was going to happen as he ran towards
    law enforcement officers fully armed. Two with long firearms; others with
    handguns. With a knife in his hand, a kitchen knife. Did he think that he was
    going to be able to somehow kill these officers, or was [it] in his mind [that] he
    wanted to be shot dead?”).
    15
    III. DISCUSSION
    While district courts have broad discretion at sentencing, this
    discretion is not unlimited. Not only must district courts abide by
    specific procedural requirements, but they must faithfully evaluate
    the record to ensure that the sentence imposed accurately and
    adequately reflects the seriousness of the offense conduct. Here, the
    District Court drastically discounted the seriousness of Mumuni’s
    offense conduct based on a sterilized and revisionist interpretation of
    the record. This clearly erroneous assessment of the evidence leaves
    us with the definite and firm conviction that a mistake has been
    committed—a mistake that resulted in a shockingly low sentence
    that, if upheld, would damage the administration of justice in our
    country.
    A. Standard of Review
    The Government has challenged only the substantive
    reasonableness of Mumuni’s sentence on appeal, and we have not
    independently identified any procedural error. Accordingly, we
    conduct only a substantive review of Mumuni’s sentence.
    We note at the threshold that our Court has not yet decided the
    standard of review that applies to unpreserved challenges of
    substantive unreasonableness. We need not do so here because we
    would hold Mumuni’s sentence substantively unreasonable even
    under the most demanding standard of review, plain error.
    16
    Our substantive review of a sentence is “akin to review under
    an ‘abuse‐of‐discretion’ standard.”30 We have repeatedly emphasized
    that “abuse of discretion” is a “distinctive term of art that is not
    meant as a derogatory statement about the district judge whose
    decision is found wanting.”31 “It is more properly understood as
    referring to occasions where, after examining trial court records, an
    appellate court reaches the informed judgment that a ruling is based
    on an erroneous view of the law or on a clearly erroneous assessment
    of the evidence,” or the district court has rendered “a decision that
    cannot be located within the range of permissible decisions.”32
    In the context of sentencing, a district court’s evaluation of the
    evidence is “clearly erroneous” when we are left with the “definite
    and firm conviction” that the district court has misinterpreted the
    record and, as a result, has misweighed certain aggravating or
    mitigating factors.33 The length of a sentence is outside “the range of
    30   United States v. Rigas, 
    583 F.3d 108
    , 114 (2d Cir. 2009).
    31United States v. Park, 
    758 F.3d 193
    , 199–200 (2d Cir. 2014); see also In re The
    City of New York, 
    607 F.3d 923
    , 943 n.21 (2d Cir. 2010) (explaining that “abuse of
    discretion” is a nonpejorative “term of art”).
    32   Park, 758 F.3d at 200 (internal quotation marks and alterations omitted).
    33Id. (internal quotation marks omitted). See generally United States v.
    Cavera, 
    550 F.3d 180
    , 191 (2d Cir. 2008) (en banc) (“At the substantive stage of
    reasonableness review, an appellate court may consider whether a factor relied on
    by a sentencing court can bear the weight assigned to it.”).
    17
    permissible decisions” when “affirming it would damage the
    administration of justice because the sentence imposed was
    shockingly high, shockingly low, or otherwise unsupportable as a
    matter of law.”34 In other words, a sentence is outside the range of
    permissible decisions when it is manifestly unjust or when it “shocks
    the conscience.”35
    “[T]he measure of what is conscience‐shocking is no calibrated
    yard stick.”36 We have observed that we “use as our lodestar the
    parsimony clause of 
    18 U.S.C. § 3553
    (a), which directs sentencing
    courts to impose a sentence sufficient, but not greater than necessary,
    to comply with the factors set out in 
    18 U.S.C. § 3553
    (a)(2)—namely,
    retribution, deterrence, and incapacitation.”37 Ultimately, what
    “shocks the conscience” depends on the “informed intuition of the
    appellate panel.”38 It is a “highly contextual”39 standard that
    34   Park, 758 F.3d at 200 (internal quotation marks omitted).
    35   Rigas, 
    583 F.3d at 123
     (internal quotation marks omitted).
    United States v. Aldeen, 
    792 F.3d 247
    , 255 (2d Cir. 2015) (internal quotation
    36
    marks omitted).
    37   Park, 758 F.3d at 200 (internal quotation marks and alterations omitted).
    38   Rigas, 
    583 F.3d at 123
    .
    39   
    Id.
    18
    “involves some degree of subjectivity”40 in its application and
    provides relief “only in the proverbial ‘rare case.’”41
    Finally, while a sentence outside the advisory Guidelines range
    is not presumptively unreasonable,42 a significant departure or
    variance from the recommended Guidelines range “should be
    supported by a more significant justification than a minor one.”43
    In sum, in reviewing a sentence for substantive reasonableness,
    we are “not disparaging the person of a trial judge, but simply
    concluding, after careful review, (1) that a sentence lacks a proper
    basis in the record, (2) that a trial judge’s assessment of the evidence
    leaves the reviewing court with a definite and firm conviction that a
    mistake has been committed, or (3) that the reviewing court has
    reached the informed judgment that a sentence is otherwise
    unsupportable as a matter of law.”44
    40   Park, 758 F.3d at 199 (internal quotation marks omitted).
    41 Rigas, 
    583 F.3d at 123
    . Notwithstanding the inherent difficulty in
    defining the precise boundaries of the “shock‐the‐conscience” standard, a
    reviewing court must not relegate itself to functioning as a mere rubber stamp for
    any sentence the district court may impose. See 
    id. at 122
     (“‘[R]easonableness’ is
    not a code‐word for ‘rubber stamp.’” (quoting United States v. Moreland, 
    437 F.3d 424
    , 433 (4th Cir. 2006))).
    42   See Gall v. United States, 
    552 U.S. 38
    , 47 (2007).
    43   
    Id. at 50
    .
    44   Park, 758 F.3d at 200–01.
    19
    B. Application
    Upon review of the record, we identify three errors that render
    Mumuni’s sentence substantively unreasonable.
    First, the District Court relied on a sterilized account of the
    attack that is unsupported by the record and that contradicts the
    District Court’s own findings at Mumuni’s guilty plea hearing. The
    District Court’s inability to accurately assess the record, in turn,
    resulted in its underappreciation of the materiality of the assault as
    an attempt to murder Agent Coughlin.
    Second, the District Court’s rationale for the disparity between
    Mumuni’s sentence (17 years) and Saleh’s sentence (18 years) is also
    unsupported by the record and appears to contradict the District
    Court’s earlier suggestion45 that, in light of the violent attack on a law
    enforcement agent, a more severe sentence than Saleh was fully
    justified.
    Third, the District Court placed undue weight on factors that
    cannot bear the weight assigned to them under the totality of
    circumstances. Jointly and severally, these errors caused the District
    45 See GA 174 (Saleh sentencing) (Court: “I know the Government is
    arguing to me that he shouldn’t get a break because they thwarted what he was
    trying to do, but I can’t sentence him for what he might have done. His co‐
    conspirator, Mr. Mumuni, did attack law enforcement . . . .”).
    20
    Court to render a sentence that is shockingly low and unsupportable
    as a matter of law.
    1. The District Court impermissibly second‐guessed
    whether Mumuni intended to kill Agent Coughlin
    and whether his eight‐inch kitchen knife
    constituted a dangerous or deadly weapon.
    It is well‐established that a district court cannot accept a guilty
    plea unless it is satisfied that there is a factual basis for the plea.46
    Here, Mumuni pleaded guilty to, inter alia, attempted murder of a
    federal officer, in violation of 
    18 U.S.C. § 1114
    (3), and assault of a
    federal officer with a deadly or dangerous weapon, in violation of 
    18 U.S.C. § 111
    (a)(1) and (b). “[A]n attempt to commit murder requires a
    specific intent to kill.”47 Moreover, the question of whether an object
    constitutes a dangerous weapon hinges, in part, on “the manner in
    which the object is used,” as “many objects, even those seemingly
    innocuous, may constitute dangerous weapons.”48
    46See FED. R. CRIM. P. 11(b)(3); see also North Carolina v. Alford, 
    400 U.S. 25
    ,
    35 n.8 (1970).
    See United States v. Kwong, 
    14 F.3d 189
    , 194 (2d Cir. 1994) (“Although a
    47
    murder may be committed without an intent to kill, an attempt to commit murder
    requires a specific intent to kill.” (internal quotation marks omitted)).
    United States v. Matthews, 
    106 F.3d 1092
    , 1095 (2d Cir. 1997) (internal
    48
    quotation marks omitted).
    21
    Accordingly, before accepting Mumuni’s guilty plea, the
    District Court was required to ensure that the following essential
    elements were supported by an independent basis in fact: (1)
    Mumuni intended to kill Agent Coughlin when he lunged at him
    with an eight‐inch kitchen knife; and (2) either the eight‐inch kitchen
    knife was an inherently dangerous weapon or the manner in which
    Mumuni wielded the knife rendered it a dangerous weapon.
    Mumuni’s allocution provided an ample basis for each of these
    determinations:
    Mumuni: Between May 2015 and June 2015 .
    . . I knowingly and intentionally agreed
    with others to forcibly oppose and impede
    any law enforcement officer who would
    prevent me from traveling overseas to join
    ISIL in the Middle East by use of [a]
    dangerous or deadly weapon. In June 2015, I
    lunged at a law enforcement officer with a
    knife. . . .
    I did deliberately and intentionally attempt
    to kill a law enforcement officer by
    [lunging] at him with a knife knowing that
    if I succeeded in my attempt I could kill
    him.
    Court: Was that your intent?
    22
    Mumuni: Yes, your Honor.49
    What’s more, after the Government prudently expressed some
    concern about the sufficiency of Mumuni’s allocution regarding his
    intent to kill Agent Coughlin, the District Court actually revisited this
    element:
    Government: Your Honor, I believe there
    are a couple of elements which we need to
    address. . . . [W]ith respect to Count Five,
    attempted murder of federal officers, we
    would have to prove that the defendant
    acted with malice aforethought and that he
    acted with premeditation. . . .
    Court: I thought he allocuted to that also,
    the attempted murder. So Mr. Mumuni, it
    sounds like you were planning to go abroad
    to assist ISIS. You knew that you were being
    surveilled by law enforcement. Correct?
    Mumuni: Yes, your Honor.
    49   GA 55–56.
    23
    Court: And at some point, did you make
    plans to prevent law enforcement or to
    attack them in some way, [thereby]
    preventing them from stopping you, as you
    indicated?
    Mumuni: Yes, your Honor.
    Court: You allocuted that it was your intent
    to murder them, if necessary; is that
    accurate?
    Mumuni: Yes, your Honor.
    Court: And, so, when you lunged at law
    enforcement on June 17, 2015, did you do so
    with the intent to murder them if necessary?
    And you can take a minute and speak to
    your attorney if you need to. The issue,
    [counsel], is whether or not he acted with
    premeditation, planning, and deliberation
    and, also, whether it was willful.
    Mumuni: I knew by lunging with them at a
    knife [sic], if I succeeded in my attempt I
    could kill them.
    24
    Court: Okay. I believe that satisfies all of the
    elements.50
    The District Court thereupon accepted Mumuni’s guilty plea.51
    Nevertheless, at sentencing, the District Court appeared to second‐
    guess whether Mumuni actually had the intent to kill Agent
    Coughlin during his attack and whether he wielded the knife in a
    manner capable of inflicting serious bodily injury:
    Court: My understanding of what your
    intent was at that point in time, on that day
    when you were arrested, that you planned
    on defending yourself, even if it meant that
    you would die. Did you intend to kill the
    agent? It’s not clear to me that you did. You
    had a knife, a kitchen knife. . . .
    Did Mr. Mumuni really think he could do
    damage with that knife? I don’t know.
    50   
    Id.
     at 60–63.
    51Id. at 63 (“I find that the defendant is fully competent and capable of
    entering an informed plea, that he is aware of the nature of the charges and the
    consequences of the plea, and that his plea of guilty to each count is a knowing
    and voluntary plea and is supported by an independent basis in fact containing
    the essential elements of the offense.”).
    25
    But I heard Agent Coughlin’s testimony,
    and I understand that he was threatened
    and that he believed under the
    circumstances that, yes, you could have
    killed him. And I’ll credit his statement that
    that could have been the outcome whether
    you intended it or not. Maybe your intent
    was only that you would die, but you could
    have killed him.52
    Not only are these musings plainly contradicted by the record,
    but they are also unsupportable as a matter of law. First, the only
    legally permissible inference to be drawn from Mumuni’s guilty plea
    is that he had the specific intent to kill Agent Coughlin. Second,
    Agent Coughlin’s testimony and the physical evidence of the attack
    confirm, beyond any reasonable doubt, that Mumuni intended to kill
    Agent Coughlin. Had Mumuni’s intent been merely to injure Agent
    Coughlin, he would not have stabbed Agent Coughlin repeatedly or
    struck him with enough force to break the tip off the knife and dent
    Agent Coughlin’s metal magazine carrier. Finally, the District Court,
    having accepted Mumuni’s plea of guilty to assault of a federal
    officer with a deadly or dangerous weapon, was not entitled to
    second‐guess the potential lethality of an eight‐inch kitchen knife. Of
    course, if the District Court did have reasonable second thoughts
    52   
    Id.
     at 214–15.
    26
    about its own earlier findings, it was required to vacate the guilty
    plea that it had accepted the first time around.
    Any speculation by the District Court that Mumuni may have
    only sought to “defend himself” is also unsupportable as a matter of
    law. Mumuni was the initial aggressor in the altercation with Agent
    Coughlin; as such, he could not, as a matter of law, have been acting
    in self‐defense.53 Nor is it relevant that Mumuni claims to have been
    merely committing “suicide by cop.”54 His alleged ulterior motive in
    attacking Agent Coughlin does not negate his specific intent to kill.
    Put differently, even if Mumuni wanted to be shot, his intent to kill
    Agent Coughlin is irrefutable. After all, Mumuni kept his weapon
    concealed behind his back until the last minute, when it was too late
    for Agent Coughlin to take any defensive action. Had his intent been
    strictly to provoke a lethal response, he could have, as Agent
    Coughlin suggested during his testimony, come downstairs
    “[waving] that knife around . . . [and law enforcement] would have
    shot him before he got to the bottom of the stairs.”55
    The District Court’s clearly erroneous findings and legal error
    resulted in its improper discounting of the seriousness of Mumuni’s
    53See United States v. Desinor, 
    525 F.3d 193
    , 198 (2d Cir. 2008) (“It has long
    been accepted that one cannot support a claim of self‐defense by a self‐generated
    necessity to kill.” (internal alterations and quotation marks omitted)).
    54   See supra note 29.
    55   GA 204.
    27
    offense conduct. Mumuni’s attack was not a spontaneous assault of a
    federal officer amid a heated altercation. Nor was it an act of self‐
    defense. Mumuni’s violent attack against Agent Coughlin was
    indisputably a premeditated, willful, and deliberate attempt to
    murder a federal officer in the name of ISIS. In short, it was a pre‐
    authorized ISIS terrorist attack on American soil.
    We are confident that if the District Court had fully
    appreciated the heinous nature of this offense—including its terrorist
    design—it would have reconsidered the weight ultimately accorded
    several aggravating factors, such as: (1) the nature and circumstances
    of the offense; (2) the need for the sentence imposed to reflect the
    seriousness of the offense, to promote respect for the law, and to
    provide just punishment for the offense; (3) the need for the sentence
    imposed to afford adequate deterrence to criminal conduct; and (4)
    the need to protect the public from further crimes of the defendant.
    2. Mumuni’s 17‐year sentence was disproportionately
    lenient compared to Saleh’s 18‐year sentence.
    In downplaying the significance of Mumuni’s assault, the
    District Court overlooked one of the most salient distinctions
    between Mumuni and Saleh. To wit, Saleh, unlike Mumuni, was
    convicted only of simple assault and was never charged with
    attempted murder of a federal officer. This charging distinction
    explains why Mumuni’s advisory Guidelines range was 85 years,
    28
    while Saleh’s was only 53.56 Yet the District Court never so much as
    mentioned this aggravating factor at Mumuni’s sentencing. Instead,
    it treated Mumuni and Saleh as if they had been convicted of similar
    conduct, and narrowed the scope of its comparison between the two
    defendants to their respective roles within the conspiracy to provide
    material support to ISIS:
    Unlike Mr. Saleh, your codefendant, you
    were not the leader of any group. In fact,
    you were recruited to participate in this
    group. There is no evidence that you
    recruited anyone else to follow ISIS. There’s
    56 Both Mumuni and Saleh were charged with, and pleaded guilty to,
    conspiracy to provide material support to a foreign terrorist organization, 18
    U.S.C. § 2339B(a)(1), attempt to provide material support to a foreign terrorist
    organization, id., and conspiracy to assault federal officers, id. § 371. These three
    charges collectively carry a statutory maximum sentence of 45 years’
    imprisonment.
    Both defendants also pleaded guilty to assault of a federal officer, id. § 111,
    but only Mumuni pleaded guilty to assault with a dangerous or deadly weapon
    under § 111(b). By contrast, Saleh pleaded guilty to the lesser‐included offense of
    forcibly impeding federal law enforcement officers, which does not include as an
    element the use of a dangerous or deadly weapon. Accordingly, the statutory
    maximum for Mumuni’s assault charge was 20 years, while Saleh’s was only 8
    years.
    Finally, only Mumuni pleaded guilty to attempted murder of a federal
    officer, id. § 1143(3), which carries a statutory maximum of 20 years’
    imprisonment.
    29
    no evidence that you praised ISIS’ heinous
    actions, as your codefendant did, or that
    you translated any ISIS propaganda for
    others, as Mr. Saleh did. Unlike Mr. Saleh,
    when you were arrested, you gave a full
    statement. . . .57
    By ignoring Mumuni’s significantly more violent assault, the District
    Court treated Mumuni and Saleh as if they had engaged in
    comparable conduct, which is simply not true.
    Perhaps more concerning, however, is that the District Court
    relied on the comparison between Mumuni and Saleh’s conduct only
    when it served as a mitigating factor. At Saleh’s sentencing, for
    example, the District Court noted that while it could not sentence
    Saleh “for what he might have done,” Mumuni, by contrast, “did
    attack law enforcement.”58 Yet at Mumuni’s sentencing eleven weeks
    later, where his comparatively violent conduct served as an
    aggravating factor, there was no mention of this distinction. Where,
    as here, a sentencing court opts to compare the relative culpability of
    co‐defendants, it cannot selectively rely on a factor when it serves a
    mitigating function in one case, but then ignore the same factor when
    it serves an aggravating function in the other case.
    57   GA 216.
    58   Id. at 174.
    30
    In sum, the District Court substantively erred by imposing a
    sentence that does not adequately reflect Mumuni’s more serious
    conduct. While Saleh may have been higher in the ISIS pecking order
    than Mumuni, it was Mumuni—not Saleh—who pleaded guilty to a
    violent act of terrorism that, but for a fortuity beyond his control,
    could easily have resulted in Agent Coughlin’s death.
    3. The mitigating factors relied on by the District
    Court cannot bear the weight assigned to them.
    The District Court principally relied on four mitigating factors
    in support of its decision to impose a sentence 80% below the
    advisory Guidelines range: (1) Mumuni’s relative youth at the time
    he committed the offense; (2) his lack of an existing criminal record;
    (3) his lack of any disciplinary infractions during his three years of
    pre‐trial and pre‐sentencing incarceration; and (4) letters of support
    from family members and friends that “describe a very different
    Mumuni than the one who was arrested that morning.”59 An 80%
    downward departure from the Guideline range is remarkable,
    especially considering the totality of circumstances in this case.
    Without applying any presumption, rigid formula, or specific
    proportionality requirement, we echo the “uncontroversial”
    proposition that a District Court’s “major departure [from the
    Guidelines] should be supported by a more significant justification
    59   GA 216.
    31
    than a minor one.”60 We conclude that, in light of the totality of
    circumstances, the first three factors cannot bear the weight assigned
    to them by the District Court.
    First, no substantially mitigating weight can be borne here by
    the fact that Mumuni did what was plainly required of him—that is,
    behaving himself in prison. Mumuni may, in due course, receive a
    reward for his compliance with institutional disciplinary regulations
    through good time credit.61 Moreover, his compliance with
    institutional regulations has no bearing on the sentencing factors a
    district court must consider under 
    18 U.S.C. § 3553
    (a). By contrast,
    had Mumuni failed to abide by institutional regulations, his
    continued disrespect of the rules would suggest a greater need to
    protect the public from further crimes and to deter future criminal
    conduct.
    Similarly, we conclude that Mumuni’s age and lack of prior
    criminal record cannot bear the mitigating weight assigned to them.
    In this case involving terrorism and such serious offense conduct, the
    District Court’s reliance on these mitigating factors produced a
    60   Gall v. United States, 
    552 U.S. 38
    , 50 (2007).
    61 See 
    18 U.S.C. § 3624
    (b)(1) (providing that “a prisoner who is serving a
    term of imprisonment of more than 1 year . . . may receive credit toward the
    service of [that] sentence . . . of up to 54 days at the end of each year of the
    prisoner’s term of imprisonment” if the Bureau of Prisons determines that
    “during that year, the prisoner has displayed exemplary compliance with
    institutional disciplinary regulations”).
    32
    sentence that shocks the conscience and cannot be located within a
    permissible range of decisions. Although we owe deference to
    sentencing judges, it is also our duty to assess the totality of
    circumstances and “patrol the boundaries of reasonableness.”62 The
    District Court’s sentence here exceeded those boundaries.
    In sum, three of the four factors relied upon by the District
    Court as mitigating cannot serve as a justification for so lenient a
    sentence.
    *       *       *
    We conclude by underscoring that the Guidelines, while only
    advisory,63 appropriately reflect Congress’s considered judgment that
    62   United States v. Cavera, 
    550 F.3d 180
    , 191 (2d Cir. 2008).
    63   See United States v. Booker, 
    543 U.S. 220
     (2005).
    33
    terrorism is different from other crimes.64 65 “[T]errorism represents a
    particularly grave threat because of the dangerousness of the crime
    and the difficulty of deterring and rehabilitating the criminal.”66
    Moreover, when it comes to sentencing terrorism, Congress and the
    United States Sentencing Commission “plainly intended for the
    punishment of crimes of terrorism to be significantly enhanced
    64 See, e.g., Violent Crime Control and Law Enforcement Act of 1994, Pub.
    L. No. 103–322, § 120004, 
    108 Stat. 1796
    , 2022 (directing the United States
    Sentencing Commission to create an “enhancement” for prison sentences
    resulting from felonies involving or intending to promote international terrorism);
    Antiterrorism and Effective Death Penalty Act of 1996, Pub. L. No. 104‐132, § 730,
    
    110 Stat. 1214
    , 1303 (extending the enhancement to domestic terrorism offenses);
    U.S.S.G. § 3A1.4 (enforcing the aforementioned congressional directives by
    directing district courts to increase a defendant’s offense level by 12 and his
    criminal history category to VI if his felony “involved, or was intended to
    promote, a federal crime of terrorism”); id. app. C, amend. 637 (2002) (imposing
    base offense Guidelines for crimes of terrorism, including providing material
    support or resources to a designated foreign terrorist organization) (“This
    amendment is a six‐part amendment that responds to the Uniting and
    Strengthening America by Providing Appropriate Tools Required to Intercept and
    Obstruct Terrorism (USA PATRIOT Act) Act of 2001, Pub. L. 107–56.”).
    65 See, e.g., Uniting and Strengthening America by Providing Appropriate
    Tools Required to Intercept and Obstruct Terrorism (USA PATRIOT ACT) Act of
    2001, Pub. L. No. 107–56 § 810, 
    115 Stat. 272
    , 380 (amending 18 U.S.C.
    § 2339B(a)(1)—which criminalizes the provision of material support or resources
    to designated foreign terrorist organizations—to increase the statutory maximum
    sentence from 10 to 15 years and authorizing a life sentence if the death of any
    person results); Uniting and Strengthening America by Fulfilling Rights and
    Ensuring Effective Discipline Over Monitoring Act of 2015, Pub. L. No. 114–123, §
    702, 
    129 Stat. 268
    , 300 (amending 18 U.S.C. § 2339B(a)(1) again to increase the
    statutory maximum sentence from 15 to 20 years).
    66   United States v. Meskini, 
    319 F.3d 88
    , 92 (2d Cir. 2003).
    34
    without regard to whether, due to events beyond the defendant’s
    control, the defendant’s conduct failed to achieve its intended deadly
    consequences.”67 Thus, in determining what constitutes a
    “sufficient”68 sentence for a terrorist defendant whose conduct did
    not result in death or physical injury, a sentence at the high end of
    the applicable range may plainly be reasonable if supported by the
    balance of § 3553(a) factors.69
    67United States v. Stewart, 
    590 F.3d 93
    , 175 (2d Cir. 2009) (Walker, J.,
    concurring in part and dissenting in part).
    68 
    18 U.S.C. § 3553
    (a) (“The court shall impose a sentence sufficient, but not
    greater than necessary . . . .”).
    69 Recently, in United States v. Pugh, 
    937 F.3d 108
     (2d. Cir 2019), we vacated
    the statutory maximum sentence of 420 months’ imprisonment for a defendant
    who had been convicted, following a jury trial, of attempting to provide material
    support to a foreign terrorist organization (ISIS) and obstruction of justice.
    Because the sentence was vacated on grounds of procedural unreasonableness
    only, Pugh does not preclude or affect a sentencing court’s ability to impose the
    maximum sentence for a terrorist defendant. It merely requires that the court, as
    always, articulate its reasons for imposing the maximum sentence.
    35
    III. CONCLUSION
    To summarize, we hold as follows:
    (1) Mumuni’s sentence of 17 years’ imprisonment—which
    constitutes an 80% reduction from his recommended
    Guidelines range of 85 years—is substantively unreasonable in
    light of his exceptionally serious conduct involving a domestic
    terrorist attack against law enforcement in the name of ISIS.
    (2) Where a district court has accepted a defendant’s guilty
    plea and his allocution to the elements of each charged offense,
    it cannot make findings of fact during sentencing that
    contradict or otherwise minimize the conduct described at the
    defendant’s plea hearing.
    (3) Where a sentencing court opts to compare the relative
    culpability of co‐defendants, it cannot selectively rely on a
    factor when it serves a mitigating function in one case, but then
    subsequently ignore the same factor when it serves an
    aggravating function in the other case.
    (4) A defendant’s legally‐required compliance with
    institutional regulations during his term of pre‐trial and pre‐
    sentencing detention is not a substantially mitigating factor for
    purposes of sentencing.
    36
    (5) At Mumuni’s resentencing, the District Court, on the basis
    of the record that supported Mumuni’s guilty plea, shall
    accord substantially greater weight to the following 
    18 U.S.C. § 3553
    (a) factors:
    (a) the nature and circumstances of the offense;
    (b) the need for the sentence imposed to reflect the
    seriousness of the offense, to promote respect for the
    law, and to provide just punishment for the offense;
    (c) the need for the sentence imposed to afford adequate
    deterrence to criminal conduct; and
    (d) the need to protect the public from further crimes of
    the defendant.
    For the foregoing reasons, Mumuni’s sentence is substantively
    unreasonable. Accordingly, we REMAND for resentencing in
    accordance with this opinion.
    In the interest of judicial economy, any subsequent appeal in
    this case shall be directed to this panel.
    37
    PETER W. HALL, Circuit Judge, concurring in part and dissenting in
    part:
    “We set aside a district courtʹs sentence as substantively
    unreasonable only if affirming it would damage the administration of
    justice because the sentence imposed was shockingly high,
    shockingly low, or otherwise unsupportable as a matter of
    law.” United States v. Douglas, 
    713 F.3d 694
    , 700 (2d Cir. 2013)
    (quotation marks and ellipsis omitted) (emphasis added). As an
    initial matter, I do not believe the seventeen‐year sentence is
    shockingly low and, therefore, I must dissent in part.
    In reviewing a sentence for substantive reasonableness, we
    “take into account the totality of the circumstances.” Gall v. United
    States, 
    552 U.S. 38
    , 51 (2007). I concur in the majority’s opinion insofar
    as it provides the District Court the opportunity to clarify, if possible,
    and further explicate in detail why, after having heard Mumuni’s
    sworn allocution and thereafter having accepted Mumuni’s guilty
    plea, it second‐guessed whether Mumuni intended to kill a federal
    officer. See Majority Op., ante at 21–28. If the District Court cannot do
    so, then I agree with the majority that the District Court must accept
    the facts as admitted under oath by Mumuni and sentence him with
    these facts in mind.
    That said, I respectfully dissent from those parts of the
    majority’s decision discussing what the majority identifies as the
    second and third errors that render Mumuni’s sentence substantively
    unreasonable. See Majority Op., ante at 29–35. I acknowledge that
    reasonable judges can differ in their respective assessments of this
    38
    record, and I consider each of the three of us to be reasonable. From
    my perspective, given the deferential standard of review we must
    apply, I disagree that this case requires imposition of a different
    sentence if, upon studied consideration of all factors that are and will
    become applicable at the time of resentencing, the District Court
    determines that a sentence similar to the present one is appropriate.
    As the majority notes, this Court has not decided whether an
    unpreserved challenge to the substantive reasonableness of a
    sentence is reviewed under the standard of plain error or of abuse of
    discretion. United States v. Thavaraja, 
    740 F.3d 253
    , 259 n.4 (2d Cir.
    2014). I would not find error under even the less stringent standard.
    “The abuse‐of‐discretion standard incorporates de novo review of
    questions of law (including interpretation of the Guidelines) and
    clear‐error review of questions of fact.” United States v. Legros, 
    529 F.3d 470
    , 474 (2d Cir. 2008). For a finding of fact to be clearly
    erroneous, we must be “left with the definite and firm conviction that
    a mistake has been committed.” United States v. Cuevas, 
    496 F.3d 256
    ,
    267 (2d Cir. 2007) (quoting United States v. Hazut, 
    140 F.3d 187
    , 190
    (2d Cir. 1998)). We set aside a district courtʹs sentence as
    substantively unreasonable “only in exceptional cases where the trial
    courtʹs decision cannot be located within the range of permissible
    decisions.” United States v. Cavera, 
    550 F.3d 180
    , 189 (2d Cir. 2008) (en
    banc) (internal quotation marks omitted).
    I for one do not think this is one of those exceptional cases. In
    my view the District Court considered Mumuni as an individual and
    carefully compared his conduct to that of his co‐defendant Munther
    39
    Saleh. Those sentencing determinations were well within the sound
    discretion of the District Court. There is no doubt that this is a
    difficult case, but I fear the majority would prefer to substitute its
    sentencing preference for that of the District Court.
    I. Comparative Leniency of Mumuni’s Sentence
    Affording appropriate deference to the District Court, I cannot
    conclude that it imposed a disproportionately lenient sentence on
    Mumuni compared to his co‐defendant Saleh. The District Court’s
    statements at sentencing show that it carefully compared the nature
    of Mumuni’s offense conduct to Saleh’s. The court “considered the
    need to avoid unwarranted disparities, but also considered the need
    to avoid unwarranted similarities among other co‐conspirators who
    were not similarly situated.” Gall, 
    552 U.S. at
    55–56. Saleh, who
    received an 18‐year aggregate sentence, was older than Mumuni and
    was the person who radicalized Mumuni and who played a more
    significant role in the parties’ conspiracy and attempt to provide
    support to ISIS. 70 The court gave Mumuni a shorter sentence than
    Saleh for the first and second counts because it distinguished
    Mumuni’s plot of a defensive course of action (a contingent
    confrontation with law enforcement if they impeded his travels to
    join the fight in the Middle East) from Saleh’s plan (an unprovoked
    70 The court did not find credible the government’s contention that Mumuni
    conspired with Saleh to build and detonate a pressure‐cooker bomb. This is an area
    in which we owe the District Court deference given the ambiguities in the record.
    40
    affirmative attack in this country), a distinction that is not
    unreasonable.
    In addition, the District Court expressly considered the
    seriousness of Mumuni’s attack on the federal officer. The court
    stated that, of the crimes Mumuni committed, it believed the
    attempted murder of a federal officer was the most serious and
    sentenced Mumuni to 204 months in custody on that count. This
    concurrent sentence amounted to an additional 84 months over and
    above the terms of imprisonment imposed on Mumuni’s other
    charges. The court believed that additional 84 months for attempted
    murder was sufficient and not greater than necessary to comply with
    the purposes of sentencing. Based on the record and affording
    appropriate deference to the District Court, I cannot say the court
    abused its discretion much less plainly erred.
    II. The Mitigating Factors
    Finally, in my view the majority opinion improperly curtails
    the discretion afforded to district courts in evaluating mitigating
    evidence when sentencing. “[S]entencing judges exercise a wide
    discretion in the types of evidence they may consider when imposing
    sentence [sic] and that highly relevant—if not essential—to the
    selection of an appropriate sentence is the possession of the fullest
    information possible concerning the defendantʹs life and
    characteristics.” Pepper v. United States, 
    562 U.S. 476
    , 480 (2011)
    (quoting Williams v. New York, 
    337 U.S. 241
    , 246–247 (1949)) (internal
    quotation marks and brackets omitted). This discretion is based on
    41
    “longstanding principles of federal sentencing law and Congressʹ
    express directives in [18 U.S.C.] §§ 3661 and 3553(a).” Id. Section 3661
    states, “[n]o limitation shall be placed on the information concerning
    the background, character, and conduct of a person convicted of an
    offense which a court of the United States may receive and consider
    for the purpose of imposing an appropriate sentence.” § 3661
    (emphasis added); see also Pepper, 
    562 U.S. at
    488–89 (noting that the
    Sentencing Commission expressly preserved this discretion in the
    Guidelines).
    Here, the District Court considered Mumuni’s young age and
    lack of criminal record, letters from Mumuni’s family and friends
    that “describe a very different Mumuni than the one who was
    arrested that morning,” and Mumuni’s discipline‐free record during
    his almost three‐year incarceration. Gov. App. 216–17. The court
    balanced this individualized view of Mumuni against his “conduct
    [that was] grave, reprehensible, and . . . deserv[ing] [of] serious
    punishment.” Gov. App. 216. This was, and continues to be, exactly
    the type of individualized consideration to which we owe deference.
    I respectfully disagree with the majority’s suggestion that the
    District Court should weigh mitigating factors differently in cases
    involving terrorism and serious offense conduct. See Majority
    Op., ante at 34. Even in capital crimes, the Supreme Court has noted
    that “the definition of crimes generally has not been thought
    automatically to dictate what should be the proper penalty.” Lockett
    v. Ohio, 
    438 U.S. 586
    , 602 (1978). That is because criminal cases are sui
    generis. “It has been uniform and constant in the federal judicial
    42
    tradition for the sentencing judge to consider every convicted person
    as an individual and every case as a unique study in the human
    failings that sometimes mitigate, sometimes magnify, the crime and
    the punishment to ensue.” Koon v. United States, 
    518 U.S. 81
    , 113
    (1996).
    Moreover, the mitigating factors highlighted in the majority
    opinion–age and lack of criminal history–are unquestionably relevant
    to the purposes of punishment. The purposes of punishment set out
    in 
    18 U.S.C. § 3553
    (a)(2), “are, broadly speaking, proportionality,
    deterrence, incapacitation, and rehabilitation.” Douglas, 713 F.3d at
    700; see also § 3553(a) (“The court shall impose a sentence sufficient,
    but not greater than necessary, to comply with the purposes set forth
    in . . . this section.”).
    The Supreme Court has repeatedly emphasized that significant
    gaps in characteristics like maturity and susceptibility to peer
    influence make “children . . . constitutionally different from adults
    for purposes of sentencing.” Miller v. Alabama, 
    567 U.S. 460
    , 471
    (2012) (citing Roper v. Simmons, 
    543 U.S. 551
    , 569–570 (2005);
    and Graham v. Florida, 
    560 U.S. 48
    , 68 (2010)).
    First, children have a lack of maturity and an
    underdeveloped sense of responsibility, leading to
    recklessness, impulsivity, and heedless risk‐taking.
    Second, children are more vulnerable to negative
    influences and outside pressures, including from their
    family and peers; they have limited control over their
    own environment and lack the ability to extricate
    43
    themselves from horrific, crime‐producing settings. And
    third, a childʹs character is not as well formed as an
    adultʹs; his traits are less fixed and his actions less likely
    to be evidence of irretrievable depravity.
    Montgomery v. Louisiana, 
    136 S. Ct. 718
    , 733 (2016) (quoting Miller,
    Roper and Graham) (internal quotation marks and citation omitted);
    see also Gall, 
    552 U.S. at 58
     (“[I]t was not unreasonable for the District
    Judge to view [21‐year‐old] Gallʹs immaturity at the time of the
    offense as a mitigating factor, and his later behavior as a sign that he
    had matured and would not engage in such impetuous and ill‐
    considered conduct in the future.”); Johnson v. Texas, 
    509 U.S. 350
    , 367
    (1993) (finding, in the case of a 19‐year‐old convicted of murder, that
    “[t]here is no dispute that a defendantʹs youth is a relevant mitigating
    circumstance . . . . Our cases recognize that ‘youth is more than a
    chronological fact. It is a time and condition of life when a person
    may be most susceptible to influence and to psychological damage’”
    (quoting Eddings v. Oklahoma, 
    455 U.S. 104
    , 115 (1982))). In addition, a
    defendant’s prior criminal history is an integral part of our
    sentencing scheme. See, e.g., Nichols v. United States, 
    511 U.S. 738
    , 747
    (1994). This is evidenced by state recidivism statutes and
    the criminal history component of the Sentencing Guidelines. 
    Id.
    ***
    Accordingly, I vote to REMAND to the District Court, and
    notwithstanding the majority’s instruction that no substantially
    mitigating weight can be borne by Mumuni’s behavior in prison, I
    would emphasize that at resentencing the District Court also has
    44
    “wide discretion in the sources and types of evidence used to assist
    [it] in determining the kind and extent of punishment to be
    imposed,” Pepper, 
    562 U.S. at 488
    , including “evidence of the
    defendantʹs postsentencing rehabilitation and that such evidence
    may, in appropriate cases, support a downward variance from the . . .
    Federal Sentencing Guidelines range.” 
    Id. at 481
    . It should not be out
    of the realm of possibility for the District Court to determine, after
    fully analyzing all the applicable factors including those for which
    we have ordered remand and Mumuni’s behaviors and course of
    conduct subsequent to his April 2018 sentencing, that the appropriate
    punishment to be imposed is a term of incarceration similar to that
    imposed twenty months ago. Should either party be dissatisfied with
    the new sentence, of course, that party has the right to appeal.
    45