United States v. Ishmael ( 1995 )


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  •                      UNITED STATES COURT OF APPEALS
    For the Fifth Circuit
    No. 94-40159
    UNITED STATES OF AMERICA,
    Plaintiff-Appellant,
    VERSUS
    ROHN MARTIN ISHMAEL and
    DEBRA K. ISHMAEL,
    Defendants-Appellees.
    Appeal from the United States District Court
    For the Eastern District of Texas
    (March 15, 1995)
    Before REYNALDO R. GARZA, DeMOSS, and BENAVIDES, Circuit Judges.
    DeMOSS, Circuit Judge:
    Based on the readings from a thermal imager, along with other
    circumstantial evidence, federal law enforcement officers obtained
    a warrant to search the premises of Rohn Martin Ishmael and his
    wife, Debra K. Ishmael.        The officers executed the warrant and
    discovered some firearms and 770 marijuana plants.           After being
    indicted, the Ishmaels moved to suppress the evidence on the ground
    that    the    warrantless   use    of   the    thermal   imager   was   a
    constitutionally proscribed search. The district court granted the
    Ishmaels' motion to suppress.       We now reverse.
    I.
    The   warrant     in   this   case      was   based   upon   the   following
    information:    In the late summer of 1992, a confidential source
    informed Paul Black, a Drug Enforcement Administration ("DEA")
    officer, that he/she had delivered numerous truck loads of concrete
    re-mix to the Ishmaels' secluded, rural property in Nacogdoches
    County,    Texas.    The    Ishmaels,     according    to   the   source,    took
    inordinate measures to conceal the need for the concrete.                    Rohn
    Ishmael, for example, would manually mix the concrete near the
    source's truck and then drive the concrete to another location on
    the property.       His suspicions aroused, Black entered the property
    and saw two mobile homes and a trailer.               Black, however, did not
    witness any illegal activity.
    In August 1993, Black resumed his investigation. He and three
    other officers returned to the property and followed a roughly
    built road from the front of the property to a steep embankment
    where a large hole had been made.             They observed around 60 empty
    bags of cement, a dump truck and a concrete re-mixer parked near
    the hole. The next day, Black investigated Rohn Ishmael's criminal
    record and found at least four separate marijuana-related incidents
    dating back to 1974, several of which involved the cultivation of
    marijuana. Black, along with other DEA officers, then surveyed the
    Ishmaels' property by air.         They observed a mobile home and a large
    steel building, separated by about 200 to 300 yards.                    The steel
    building stood next to a 2-acre pond.              Black entered the property
    on foot two more times.       He discovered that the Ishmaels had built
    2
    a structure beneath the steel building. The substructure was wired
    for electricity and was being fed water from the nearby pond by way
    of exposed rubber tubes and a water pump.                          The substructure also
    had an exhaust fan, which Black noticed was continuously running.
    Black also observed a nearby pallet containing 100 5-gallon plastic
    buckets.
    Suspecting that the Ishmaels were cultivating marijuana in the
    structure beneath the steel building, the DEA boarded a helicopter
    with a thermal imager and flew over the Ishmaels' property at
    approximately      500     to    1000       feet.        A    thermal    imager    detects
    differences in surface temperature of targeted objects and displays
    those differences through a viewfinder in varying shades of white
    and gray.       In other words, a warm object will appear white on the
    device's viewfinder, whereas a cool object will appear gray.                            The
    device can record its readings on a standard videocassette.                             The
    DEA's recording of the Ishmaels' property showed that, although the
    water entering the substructure was noticeably cool, the water
    exiting    it    was    emitting       a    substantial        amount    of    heat.    The
    recording additionally showed that the ground adjacent to the
    substructure was much warmer than the ground further from the
    substructure.
    Black then subpoenaed the Ishmaels' telephone records.                            The
    records indicated that the Ishmaels had made numerous calls to
    various horticulture shops, two of which appeared on a narcotics
    intelligence      computer       base       as       suppliers     for   other   marijuana
    cultivators.           Black    also       subpoenaed        the   Ishmaels'     electrical
    3
    utility records.      The records showed that the substructure's power
    usage was extremely high and far exceeded the mobile home's power
    usage.
    In September 1993, Black and several other officers again
    entered the Ishmaels' property on foot.            Using a hand-held thermal
    imager, the officers canvassed the perimeter of the steel building
    but never entered it.         The officers made essentially the same
    findings;     an   unusual   amount   of    heat   was     emanating   from   the
    substructure and the ground adjacent to it.                Black displayed his
    recordings to two DEA thermographers, both of whom concluded that
    the Ishmaels were illegally cultivating marijuana in the steel
    building's substructure.          The DEA then used the thermal imager's
    readings, along with the wealth of information gathered by Black,
    to   obtain    a   warrant   to    search   the    steel    building   and    its
    substructure on the Ishmaels' property.            The officers executed the
    warrant two days later and uncovered 770 marijuana plants and
    several firearms.        After being indicted in October 1993, the
    Ishmaels moved to suppress the evidence obtained pursuant to the
    search warrant.       They argued that the readings from the thermal
    imager constituted an unconstitutional search and that, without
    those readings, the DEA did not have probable cause to obtain a
    warrant.
    The district court granted the motion to suppress in January
    1994.    See United States v. Ishmael, 
    843 F. Supp. 205
    (E.D. Tex.
    1994). The court employed a burden-shifting analysis. The burden,
    it observed, initiated with the Ishmaels to demonstrate that they
    4
    had a reasonable expectation of privacy. The court concluded that,
    although the steel structure was outside the curtilage of the home,
    the Ishmaels nonetheless had exhibited a reasonable expectation of
    privacy. 
    Id. at 209-12.
    Specifically, it noted that "the Ishmaels
    had a reasonable expectation that their effects, associated with
    the secreted metal building and the business being conducted there,
    were safe from [g]overnmental surveillance." 
    Id. at 211.
    Pointing
    to Florida v. Riley, 
    488 U.S. 445
    (1989), and California v.
    Ciraolo, 
    476 U.S. 207
    (1986), the government argued that the
    Ishmaels did not have a reasonable expectation of privacy from the
    DEA's air surveillances.      The court rejected the government's
    argument, reasoning that those cases were limited exclusively to
    naked-eye observations.    
    Id. at 211-12.
    According to the district court, the burden then shifted to
    the government to prove that its search fell within one of the
    several recognized exceptions to the warrant requirement.      The
    government, relying on Dow Chemical Company v. United States, 
    476 U.S. 227
    (1986), argued below that the heat emissions were in
    "plain view."   The court rejected the "plain view" argument on the
    ground that the heat emissions would not be in plain view without
    the use of "sophisticated technology," namely the thermal imager.
    
    Id. at 212.
        Alternatively, the government analogized the heat
    emissions to curb-side garbage (as in California v. Greenwood, 
    486 U.S. 35
    (1988)) and the scent of cocaine emanating from luggage (as
    5
    in United States v. Place, 
    462 U.S. 696
    (1983)): because each has
    been    effectively    abandoned,       the   defendant   no   longer    has   a
    subjective expectation of privacy in its concealment.               The court
    rejected the government's analogies on the ground that the relative
    sophistication of the thermal imager poses a greater intrusion than
    officers manually rummaging through abandoned garbage or a trained
    police dog alerting to a suitcase carrying contraband.             
    Id. at 212-
    13.
    Having found that the use of the thermal imager constituted a
    search proscribed by the Fourth Amendment, the court proceeded to
    determine whether the remaining evidence amounted to probable
    cause.     The court noted that the DEA had no direct evidence of
    illegal activity taking place on the Ishmaels' property.                
    Id. at 213-14.
        The court stated, "The evidence of their activity was
    consistent    with    developing    a   new   patented    strain   of   African
    violets, and innumerable other perfectly legal activities." 
    Id. at 214.
        On this basis, the court concluded that a judge would not
    find that probable cause existed for issuing a warrant, and it
    therefore granted the Ishmaels' motion to suppress. The government
    now appeals the district court's holdings that the warrantless use
    of the thermal imager was unconstitutional and that, absent its
    readings, probable cause did not exist for the issuance of the
    warrant.
    II.
    A.
    6
    In   reviewing    a   district   court's   ruling   on   a   motion   to
    suppress, we review the court's conclusions of law de novo and its
    findings of fact for clear error.          United States v. Cardenas, 
    9 F.3d 1139
    , 1147 (5th Cir. 1993); United States v. Sanders, 
    994 F.2d 200
    , 202-03 (5th Cir. 1993).       Furthermore, we view the evidence in
    a light most favorable to the prevailing party, United States v.
    Piaget, 
    915 F.2d 138
    , 140 (5th Cir. 1990), which in this case is
    the Ishmaels.
    B.
    The warrantless use of thermal imagers by the police has
    spawned a fair amount of search and seizure jurisprudence over the
    last several years.1       Though the Fifth Circuit has yet to squarely
    address this issue,2 three of our sister circuits have, and each
    1
    See United States v. Myers, ___ F.3d ___, 
    1995 WL 38118
    (7th
    Cir. 1995); United States v. Robertson, 
    39 F.3d 891
    (8th Cir.
    1994); United States v. Kyllo, 
    37 F.3d 526
    (9th Cir. 1994); United
    States v. Ford, 
    34 F.3d 992
    (11th Cir. 1994); United States v.
    Pinson, 
    24 F.3d 1056
    (8th Cir. 1994); United States v. Olson, 
    21 F.3d 847
    (8th Cir. 1994); United States v. Deaner, 
    1 F.3d 192
    (3d
    1993); United States v. Feeney, 
    984 F.2d 1053
    (9th Cir. 1993);
    State v. Young, 
    867 P.2d 593
    (Wash. 1994); United States v. Field,
    
    855 F. Supp. 1518
    (W.D. Wis. 1994); United States v. Domitrovich,
    
    852 F. Supp. 1460
    (E.D. Wash. 1994); United States v. Porco, 842 F.
    Supp. 1393 (D. Wyo. 1994); United States v. Deaner, 
    1992 WL 209966
    (M.D. Pa. 1992); United States v. Kyllo, 
    809 F. Supp. 787
    (D. Or.
    1992), vacated on other grounds, 
    37 F.3d 526
    (9th Cir. 1994);
    United States v. Penny-Feeney, 
    773 F. Supp. 220
    (D. Haw. 1991),
    aff'd on other grounds, 
    984 F.2d 1053
    (9th Cir. 1993); see also
    Lisa J. Steele, Waste Heat and Garbage: The Legalization of
    Warrantless Infrared Searches, 29 CRIM. L. BULL. 19 (1993).
    2
    In United States v. Broussard, 
    987 F.2d 215
    (5th Cir. 1993),
    the defendant moved to suppress certain evidence on the ground that
    the affidavit the government submitted in requesting a warrant was
    insufficiently detailed. In affirming the district court's denial
    of the motion, we noted that, to the extent that the affidavit was
    inadequate, the warrant was nonetheless valid because the
    government had supplied findings from a thermal imaging device.
    7
    has concluded that such use is not a "search" proscribed by the
    Fourth Amendment.    United States v. Myers, 
    1995 WL 38118
    , at *2-*3
    (7th Cir. 1995); United States v. Ford, 
    34 F.3d 992
    , 995-97 (11th
    Cir. 1994); United States v. Pinson, 
    24 F.3d 1056
    , 1058-59 (8th
    Cir. 1994).     We now hold that the warrantless use of a thermal
    imager in an "open field" does not violate the Fourth Amendment.
    1.
    The Fourth Amendment provides in part: "The right of the
    people to be secure in their persons, houses, papers, and effects,
    against unreasonable searches and seizures, shall not be violated."
    U.S. CONST. amend. IV.      As in any Fourth Amendment surveillance
    case, our analysis begins with Katz v. United States, 
    389 U.S. 347
    (1967).     The Supreme Court in Katz enunciated its two-prong test
    for determining whether a warrantless search violated a defendant's
    legitimate    expectation   of   privacy:    the    defendant    must    have
    exhibited a subjective expectation of privacy, and that expectation
    must be one society is prepared to recognize as reasonable.             
    Id. at 361
    (Harlan, J., concurring); see also 
    Ciraolo, 476 U.S. at 211
    (majority opinion). With regard to the first prong, the government
    maintains    that   the   Ishmaels   did    not    exhibit   a   subjective
    expectation of privacy because they made no effort to conceal the
    heat emanating from the building. In fact, the Ishmaels encouraged
    emission of the heat by installing an exhaust fan that operated
    
    Id. at 222.
         Because the defendant did not challenge the
    constitutionality of the warrantless use of the device, we did not
    address the issue. See also United States v. Zimmer, 
    14 F.3d 286
    ,
    288 (6th Cir. 1994).
    8
    continuously.   Thus, the government argues, the Ishmaels clearly
    failed Katz' first prong because "[w]hat a person knowingly exposes
    to the public, even in his home or office, is not a subject of
    Fourth   Amendment   protection."       
    Katz, 389 U.S. at 351
    .     The
    Ishmaels, in response, contend that the government's argument is
    somewhat specious; while the substructure admittedly was emitting
    heat, that emission was not a deliberate act.          The law of physics,
    and not the Ishmaels' failure to contain, controlled the emission
    of heat from the substructure.           The Ishmaels argue that the
    government's "heat waste" analogy therefore is a bad one because
    one who expects his garbage to remain private can refrain from
    leaving it at the curb, whereas one who expects his heat waste to
    go undetected can only hope the police is not presently scanning
    his property with a thermal imager.
    In cases involving very similar facts, other courts have
    readily accepted the heat waste analogy in concluding that the
    defendants' have failed to satisfy Katz' first prong.             See, e.g.,
    Myers, ___ F.3d at ___; 
    Ford, 34 F.3d at 995
    ; Domitrovich, 852 F.
    Supp. at 1472-73; 
    Penny-Feeney, 773 F. Supp. at 225-26
    .                  But a
    cursory review of Katz itself demonstrates that the first prong
    probably is not as restrictive as these courts have interpreted it
    to be.    In Katz, the government, without a warrant, attached a
    recording device to the exterior of a telephone booth that the
    defendant used to illegally transmit gambling information.                 The
    defendant argued that the government's warrantless eavesdropping
    was proscribed by the Fourth Amendment, and the Supreme Court
    9
    agreed. Though the defendant in Katz did not take every precaution
    against electronic eavesdropping, the Court nonetheless concluded
    that he had exhibited a subjective expectation of privacy.                     
    Katz, 389 U.S. at 353
       (the   government's       warrantless        eavesdropping
    "violated the privacy upon which [the defendant] justifiably relied
    while using the telephone booth") (majority opinion). Likewise, in
    Ciraolo, the defendant was cultivating marijuana in his backyard,
    which was enclosed by a six-foot outer fence and a ten-foot inner
    fence.    Because the fences obstructed its view from ground level,
    the police flew over the defendant's property at 1,000 feet and
    observed the marijuana patch.          Though it ultimately concluded that
    the search was constitutional, the Court initially concluded that
    the defendant "[c]learly . . . ha[d] met the test of manifesting
    his own subjective intent and desire to maintain privacy as to his
    unlawful agricultural pursuits."                 
    Ciraolo, 476 U.S. at 211
    ; see
    also 
    Riley, 488 U.S. at 449
    ("We recognized [in Ciraolo] . . . that
    the occupant had a subjective expectation of privacy.                      We held,
    however, that such an expectation was not reasonable.").3
    Thus,    unless      we    intend     to     render    Katz'     first   prong
    meaningless,       we    must   conclude    that    the     Ishmaels    exhibited   a
    3
    Riley is further proof that a dweller need not guard against
    every possibility of detection in order to satisfy Katz' first
    prong.   The defendant in Riley was cultivating marijuana in a
    greenhouse that was missing several corrugated roofing panels.
    Flying over the greenhouse in a helicopter at 400 feet, the police
    observed marijuana through an opening in the roof. The Court found
    that the defendant "no doubt intended and expected that his
    greenhouse would not be open to public inspection." 
    Riley, 488 U.S. at 450
    .   But concluding that Ciraolo was controlling, the
    Court held that the search was nonetheless reasonable.
    10
    subjective    expectation     that   their   hydroponic     laboratory   would
    remain private.       See Smith v. Maryland, 
    442 U.S. 735
    , 740 n.5
    (1979) ("[s]ituations can be imagined, of course, in which Katz'
    two-pronged inquiry would provide an inadequate index of Fourth
    Amendment protection").4       Though the Ishmaels did not -- indeed,
    could not -- take every precaution against the detection of the
    hydroponic laboratory, the balance of the evidence demonstrates
    that the Ishmaels exhibited a subjective expectation of privacy.
    Rohn Ishmael, for example, constructed the laboratory in great
    secrecy.     In addition, it was built as a basement to a steel
    building that was not visible from a public road.               We therefore
    conclude that the Ishmaels have satisfied Katz' first prong.
    2.
    We now must address whether the government's intrusion on the
    Ishmaels' subjective expectation of privacy with a thermal imager
    is a reasonable one.    Oliver v. United States, 
    466 U.S. 170
    , 182-83
    (1984) ("the correct inquiry is whether the government's intrusion
    infringes upon the personal and societal values protected by the
    Fourth Amendment").     It is at this point in the analysis that the
    use of technology, and its degree of sophistication, becomes an
    issue, because more sophisticated forms of technology increase the
    likelihood     that   their    warrantless     use   will     constitute   an
    4
    See also 1 WAYNE R. LAFAVE, SEARCH AND SEIZURE § 2.1(c), at 308-310
    (2d ed. 1987) (generally arguing that courts should avoid the
    contemplation of unreasonable hypotheticals when applying the first
    Katz prong); David H. Steinberg, Constructing Homes for the
    Homeless? Searching for a Fourth Amendment Standard, 41 DUKE L.J.
    1508, 1516-20 (1992).
    11
    unreasonable   intrusion.      As       the   Supreme   Court   once      stated,
    "surveillance of private property by using highly sophisticated
    surveillance equipment not generally available to the public . . .
    might be constitutionally proscribed absent a warrant."                       Dow
    
    Chemical, 476 U.S. at 238
    .
    Dow Chemical provides useful guidance for search and seizure
    cases involving surveillance technology.            There, the Environmental
    Protection    Agency,    without    a    warrant,     had   flown   over   Dow's
    industrial plant with a precise mapping camera.               Dow argued that
    the use of the camera was an unconstitutional search.               The Supreme
    Court disagreed, reasoning that the government is not foreclosed
    from using technology to enhance its surveillances, provided that
    that technology does not reveal "intimate details."                 
    Id. at 238.
    The Court was satisfied that the camera did not reveal such
    "details" because it was not "some unique sensory device that, for
    example,   could   penetrate   the      walls    of   buildings     and    record
    conversations in Dow's plants, offices, or laboratories, but rather
    a conventional, albeit precise, commercial camera commonly used in
    mapmaking."    
    Id. at 238.
        Similarly, in United States v. Knotts,
    
    460 U.S. 276
    (1983), the police surveilled the defendant by means
    of an electronic beeper attached to the interior of a five-gallon
    chloroform drum.        Relying on the beeper's signals, the police
    eventually uncovered the drum just outside the residence of one of
    the defendants.    The defendant who owned the residence insisted
    that the warrantless use of the beeper was unconstitutional because
    it violated the sanctity of his home.           The Supreme Court, however,
    12
    held that the surveillance was not an unreasonable search because
    "there is no indication that the beeper was used in any way to
    reveal information as to the movement of the drum within the
    cabin."     
    Id. at 285;
    see also 
    Place, 462 U.S. at 706-07
    (specially
    trained canine sniffing luggage is not an unconstitutional search
    because it is a "limited disclosure" and involves no "embarrassment
    and inconvenience"); 
    Smith, 442 U.S. at 741-46
    (pen register, which
    discloses only the telephone numbers that have been dialed and not
    the content of communications, is not an unconstitutional search);
    United States v. Lee, 
    274 U.S. 559
    , 563 (1927) (searchlight that
    uncovered contraband from a distance was not an unconstitutional
    search).      Thus, the mere fact that the police have employed
    relatively sophisticated forms of technological surveillance does
    not render the surveillance unconstitutional.5               While technology
    certainly gives law enforcement a leg up on crime, the Supreme
    Court       has      "never      equated        police     efficiency          with
    unconstitutionality."          
    Knotts, 460 U.S. at 284
    .              The crucial
    inquiry, as in any search and seizure analysis, is whether the
    technology reveals "intimate details."             Dow 
    Chemical, 476 U.S. at 238
    .
    A thermal imager, according to the government, is no more
    intrusive     than    the     other   animate     and    inanimate     means    of
    5
    "Nothing in the Fourth Amendment prohibited the police from
    augmenting the sensory faculties bestowed upon them at birth with
    such enhancement as science and technology afforded them in this
    case." 
    Knotts, 460 U.S. at 282
    . "The Supreme Court has repeatedly
    held that the fact that a surveillance device allowed for super- or
    extra-sensory perception is not fatal to a Katz analysis." 
    Ford, 34 F.3d at 997
    .
    13
    surveillance that the Supreme Court has concluded does not offend
    the Fourth Amendment.         That is, like the trained canine in Place or
    the precise mapping camera in Dow Chemical, a thermal imager is an
    acceptable     surveillance         technique       because    it    does    not   reveal
    intimate details within the structure being scanned.                        Instead, the
    government argues, the device assesses only heat differentials in
    objects and therefore poses no threat to the privacy concerns that
    the Fourth Amendment is intended to protect. The Ishmaels contend,
    however, that a thermal imager is the functional equivalent of an
    X-ray    machine     in    that    it    allows     officers    to    "see"     within    a
    structure     what    it    otherwise        cannot    see    with   the     naked   eye.
    Specifically, they argue, a thermal imager measures heat that is
    generated within a structure and, to that extent, constitutes an
    unreasonable intrusion on one's Fourth Amendment privacy.                              The
    Ishmaels, echoing the district court below, see Ishmael, 843 F.
    Supp.    at   212,    argue       that   a   thermal    imager       is   the   type     of
    "sophisticated technology" that the Court in Dow Chemical warned
    law enforcement officials not to use without a warrant.
    The Ishmaels overstate the device's capabilities.                        The device
    "does not intrude in any way into the privacy and sanctity of a
    home."    Myers, ___ F.3d at ___.                 It "is a passive, non-intrusive
    instrument" in that "[i]t does not send any beams or rays into the
    area on which it is fixed or in any way penetrate structures within
    that area."        
    Penny-Feeney, 773 F. Supp. at 223
    .                     As the Eighth
    Circuit recently noted, "[t]he detection of the heat waste [is] not
    an intrusion into the home; no intimate details of the home [are]
    14
    observed, and there [is] no intrusion upon the privacy of the
    individuals within."    
    Pinson, 24 F.3d at 1059
    .6      The device, in
    other words, poses no greater intrusion on one's privacy than a
    precise mapping camera, an electronic beeper, or a pen register.
    The manner in which a thermal imager was used in this case is
    equally   significant   in   assessing   the   reasonableness   of   the
    intrusion. When the DEA performed its pre-dawn thermal readings in
    this case, the officers never physically invaded the Ishmael's
    residential or commercial curtilage. See Dow 
    Chemical, 476 U.S. at 237
    ("[a]ny actual physical entry by EPA into any enclosed area
    would raise significantly different questions").         The district
    court below characterized the steel building as a "business," see
    
    Ishmael, 843 F. Supp. at 210
    , and recognizing that we can review
    the court's factual finding only for clear error, we will not
    disturb the court's finding.7    But the court erred as a matter of
    law when it stated the following: "to say that the government could
    6
    The Ishmaels also overstate its accessibility, which also is
    a significant consideration. See Dow 
    Chemical, 476 U.S. at 238
    .
    As the district court in Deaner stated:
    The technology employed is "off the shelf," having been in
    general use for fifteen years. The device is utilized by many
    businesses for a variety of purposes, including the detection
    of roof leaks, steam pipe leaks, cracks in high voltage
    transmission lines and overloaded transformers.       Several
    companies market the product, which is readily available
    through purchase, rental or the services of a thermographer.
    Deaner, 
    1992 WL 209966
    , at *2.
    7
    We would reach the same conclusion even if we could apply a
    more exacting standard of review. Applying the four factors from
    United States v. Dunn, 
    480 U.S. 294
    , 300-03 (1987), the steel
    building clearly is beyond the Ishmaels' residential curtilage.
    The building, for example, stood 200 to 300 yards from the
    Ishmaels' mobile home and was not enclosed within a fence that also
    surrounded the home. See 
    Ishmael, 843 F. Supp. at 209-10
    .
    15
    intrude up to the very windows of the building on the basis of the
    ``open fields' doctrine simply because it was outside the curtilage
    of a home, would eviscerate the Fourth Amendment."       
    Id. The Supreme
    Court, in fact, has held precisely the opposite. In United
    States v. Pace, 
    955 F.2d 270
    (5th Cir. 1992), law enforcement
    officers came abreast of the defendant's barn, which stood beyond
    the residential curtilage, and peered inside the barn to observe
    the defendant's drug operation. The defendant argued that the barn
    qualified as a business and that the barn's surrounding area was
    protected under a theory analogous to the home curtilage theory.
    Noting that the Supreme Court effectively rejected this theory in
    United States v. Dunn, 
    480 U.S. 294
    , 303-05 (1987), we concluded
    that "there is no business curtilage surrounding a barn lying
    within an open field."    
    Pace, 955 F.2d at 276
    .8     The officers
    therefore were entitled to "come as close to the structure as
    necessary to look inside without physically entering."   
    Id. Similarly, the
    officers in this case were entitled to observe
    the steel building either by air or on foot because the building,
    8
    In Dunn, which involved facts nearly identical to those in
    Pace, the Supreme Court accepted for the sake of argument that the
    defendant's barn was a business. 
    Dunn, 480 U.S. at 303
    . The Court
    then stated:
    the officers never entered the barn, nor did they enter any
    other structure on respondent's premises.       Once at their
    vantage point, they merely stood, outside the curtilage of the
    house and in the open fields upon which the barn was
    constructed, and peered into the barn's open front.       And,
    standing as they were in the open fields, the Constitution did
    not forbid them to observe the phenylacetone laboratory
    located in respondent's barn. This conclusion flows naturally
    from our previous decisions.
    
    Id. at 304.
    16
    like the barn in Pace, stood in an open field.                   And, as we have
    already discussed, the fact that the officers enhanced their
    observations with a thermal imager does not require a different
    conclusion.       The device, when used in an "open field," does not
    offend     the   Fourth   Amendment     because    it    is   passive   and   non-
    intrusive.       The sanctity of one's home or business is undisturbed.
    We therefore conclude that the DEA's warrantless use of a thermal
    imager in this case was not an unconstitutional search.
    III.
    Having concluded that the warrantless use of a thermal imager
    was not unconstitutional in this case, we now turn to the question
    of whether the device's readings, in conjunction with the remainder
    of   the    evidence    the    DEA   proferred    to    the   magistrate     judge,
    established the necessary probable cause to issue the warrant.                   In
    determining whether probable cause exists, "a magistrate judge must
    make a practical, common-sense decision as to whether, given all
    the circumstances set forth in the affidavit, there is a fair
    probability that contraband or evidence of a crime will be found in
    a particular place."           United States v. Byrd, 
    31 F.3d 1329
    , 1340
    (5th Cir. 1994).          Reviewing courts (including district courts)
    should afford a magistrate judge's decision "great deference."
    Illinois v. Gates, 
    462 U.S. 213
    , 236 (1983); United States v.
    McCarty, 
    36 F.3d 1349
    , 1356 (5th Cir. 1994); United States v.
    Robertson, 
    39 F.3d 891
    , 892 (8th Cir. 1994).
    The    totality     of   the   circumstances      in    this   case   clearly
    indicates a fair probability that the Ishmaels were cultivating
    17
    marijuana in the steel building's substructure.                       Rohn Ishmael, for
    example, was extremely careful not to reveal the need for the
    concrete re-mix. The substructure had been elaborately constructed
    with its own electricity supply and was being fed water from the
    nearby      pond.         The     substructure's     exhaust      fan      operated    on   a
    continuous          basis.        In    addition,    the    Ishmaels       phone   records
    indicated          that    their       phone   had   been    used     to    call   various
    horticulture shops, two of which appeared on a law enforcement
    computer        data      base.        The   Ishmaels'     electric     utility    records
    demonstrated that the substructure was consuming an inordinate
    amount of power, particularly when compared to the mobile home's
    power      usage.         Finally,       and   perhaps     most   importantly,        expert
    thermographers analyzed the two readings from the thermal imager
    and concluded that the inordinate amount of heat emanating from the
    substructure was consistent with indoor cultivation of marijuana.
    Construing this evidence in a "common-sense manner,"9 we conclude
    that probable cause existed for the issuance of the warrant.                             See
    
    Robertson, 39 F.3d at 893-94
    (readings from a thermal imager, when
    combined           with    informant's         tip   and     police        officer's     own
    observations, establish probable cause).
    IV.
    9
    "Like the district court, . . . we construe the
    [government's] affidavit in a common-sense manner." 
    McCarty, 36 F.3d at 1356
    .
    wjl\opin\94-40159.opn
    jwl                                            18
    For the reasons stated above, the district court's order
    granting the Ishmaels' motion to suppress is REVERSED and the case
    is REMANDED to the district court for further proceedings.
    wjl\opin\94-40159.opn
    jwl                             19