Military Use of Infrared Radars Technology to Assist Civilian

Law Enforcement Agencies

T he D epartm ent o f D efense has statutory authority to assist civilian law enforcem ent agencies to 

identify or confirm suspected illegal drug production within structures located on private 

property by providing them w ith aerial reconnaissance that uses Forw ard Looking Infrared 

R adars technology.

February 19, 1991

M e m o r a n d u m O p i n i o n f o r t h e G e n e r a l C o u n s e l

D e p a r t m e n t o f D e f e n s e

This memorandum is in response to your request for our opinion whether, 

under existing statutory authority, the Department of Defense may assist 

civilian law enforcement agencies to identify or confirm suspected illegal 

drug production within structures located on private property by providing 

them with aerial reconnaissance that uses Forward Looking Infrared Radars 

technology. We conclude that such assistance is authorized by 10 U.S.C. § 

374(b)(2)(B), and not prohibited by 10 U.S.C. § 375.

I.

Forward Looking Infrared Radars (“FLIR”) is a passive technology that 

detects infrared radiation generated by heat-emitting objects. Infrared rays 

are received by the FLIR system, electronically processed, and projected on 

a screen as a visual image in the shape of the object that is emitting the heat. 

The warmer the object, the brighter the image of the object appears. See

United States v. Sanchez, 829 F.2d 757, 759 (9th Cir. 1987); United States v. 

K ilgusy 571 F.2d 508, 509 (9th Cir. 1978). FLIR is not an x-ray technology. 

We have been informed that it cannot provide information concerning the 

interior of an object or structure. It detects only heat emanating from surfaces that are directly exposed to the FLIR system. Thus, for example, if 

there were heat-producing objects within a building, FLIR could detect that 

more infrared radiation was being emitted from the building’s roof than if 

the building were empty, but the system could not identify the shapes of

36
heat-emitting objects located within the structure. Nor could the system 

identify the source of the heat or the precise location of the heat source 

within the structure.

Law enforcement agencies believe that FLIR technology can be useful in 

identifying buildings that house marijuana crops, or methamphetamine or 

other drug processing laboratories. In particular, FLIR can aid law enforcement officials in establishing probable cause that criminal activity is ongoing 

within a particular building by determining whether the building is radiating 

unusually large amounts of heat (due to the use of high intensity lighting or 

combustion generators) or unusually small amounts of heat (due to heavy 

insulation). Recently, therefore, federal and state law enforcement agencies 

have requested that military aircraft equipped with FLIR fly over suspect 

buildings on private lands and produce infrared images of those structures.

The Department of Defense (“DoD”) has informed us of three requests 

for assistance that present the question whether such military assistance is 

authorized. The Drug Enforcement Administration (“DEA”) has asked the 

Army to conduct infrared imaging of a bam on private land in which the 

DEA suspects that marijuana is being cultivated. Second, a law enforcement 

agency has requested that an Army flight crew conduct a training mission 

over certain private lands and buildings in the vicinity of Wichita, Kansas, 

using an Army helicopter equipped with FLIR, to identity suspected illegal 

marijuana cultivation. And third, the DEA has asked that the Army undertake flights in OH-58D helicopters equipped with FLIR, at a height of at 

least 500 feet above ground, to identify dwellings and other structures on 

private land in Arizona that the DEA suspects contain methamphetamine 

laboratories. The requesting agencies maintain that the Defense Department 

has the authority to provide the requested assistance under the provisions of 

10 U.S.C. §§ 371-378, which are designed to promote cooperation between 

military personnel and civilian law enforcement officials.

II.

Chapter 18 of title 10, which was enacted by Congress in 1981 and subsequently amended in 1988 and 1989, authorizes DoD to provide several 

forms of assistance to civilian law enforcement officials. Sections 371 through 

373 permit the Secretary of Defense to provide these officials with information collected during training missions; equipment or facilities needed for 

law enforcement purposes; and training or advice relevant to equipment that 

is provided. Section 374 authorizes the Secretary to make DoD personnel 

available for the operation and maintenance of equipment in connection with 

a limited number of law enforcement purposes. Each of these authorizations 

is subject to the limitations in section 375 that the Secretary of Defense 

prevent “direct participation by a member of the Army, Navy, Air Force, or

37
Marine Corps in a search, seizure, arrest, or other similar activity.” Id. § 375.1

We believe it is clear from the language and legislative history of sections 

371 through 374 that FLIR surveillance is authorized by those sections, 

subject to the restrictions of section 375.2 Section 372 permits the Secretary 

of Defense to make available to any federal, state or local law enforcement 

official “any equipment” for law enforcement purposes, and obviously FLIR 

constitutes “equipment.” Section 374, as amended, allows DoD personnel to 

operate such equipment for the purpose of “aerial reconnaissance,” which is 

precisely what is contemplated in the requests that have been made. 10 

U.S.C. § 374(b)(2)(B).3 The normal meaning of the term “reconnaissance” is 

“an exploratory or preliminary survey, inspection, or examination made to 

gain information.” Webster's Third New International Dictionary 1897 (1986). 

FLIR surveillance from aircraft is clearly “aerial reconnaissance,” so defined. The only limitation on aerial reconnaissance even suggested by the 

legislative history is that it should “be used for reconnaissance of property 

and not for surveillance of persons.” H.R. Conf. Rep. No. 989, 100th Cong., 

2d Sess. 451 (1988) (“1988 Conference Report”). Here, of course, the proposed reconnaissance is of property, not persons. We conclude, therefore,

'T h e scope of section 375 is itself restricted by 10 U.S.C. § 378, which states that “[n]othing in this 

chapter shall be construed to limit the authority of the executive branch in the use of military personnel 

or equipm ent for civilian law enforcement purposes beyond that provided by law before December 1, 

1981.” Thus, if FLIR surveillance of private buildings would not have been prohibited by the Posse 

Comitatus Act, 18 U.S.C. § 1385, before 1981, section 375 does not proscribe such surveillance. See

infra note 16.

2 All parties who have reviewed the requests for DoD assistance that are at issue here appear to agree 

with this conclusion. Memorandum for Terrence O’Donnell, General Counsel, Department of Defense, 

from Robert M. Smith, Jr., at 32-33 (Sept. 19,1980) (“Smith Memorandum”); Memorandum for Office of 

the Deputy C hief of Staff for Operations and Plans, from Patrick J. Parrish, Assistant to the General 

Counsel, Department of the Army at 1 (Sept. 17, 1990) (“Parrish Memorandum”); Memorandum for 

Joint Chiefs of Staff, from Lt. Col. C.W. Hoffman, Jr., Deputy LLC at 1 (Aug. 14, 1990) (“Hoffman 

M emorandum”).

3 Originally, section 374 authorized DoD personnel to operate equipment “only to the extent the equipment is used for monitoring and communicating the movement of air and sea traffic," and in certain 

emergency circumstances. Department of Defense Authorization Act, 1982, Pub. L. No. 97-86, tit. IX, 

§ 905(a)(1), 95 Stat. 1099, 1115 (1981). At the time, Congress believed these were the “primary type[s] 

of assistance sought and needed by Federal drug enforcement agencies.” H.R. Conf. Rep. No. 311, 97th 

Cong., 1st Sess. 120 (1981) (“1981 Conference Report”).

W hen it added the authority for military aerial reconnaissance assistance in 1988, Congress intended 

to perm it military assistance not only in connection with the interdiction of drugs bound for the United 

States from foreign countries, but also in connection with the eradication of domestically produced 

narcotics. Several witnesses before the House and Senate Armed Services Committees testified that 

DoD assistance in the domestic “drug war” was in high priority. See The Role o f the Military in Drug

Interdiction: Joint Hearings Before the House and Senate Armed Services Committees, 100th Cong.. 

2d Sess. 187 (1988) (statement of Larry L. Orton, Special Agent in Charge, El Paso Intelligence Center, 

Drug Enforcement Agency) ("We further believe that the National Guard [should] help us in the role 

that we have here domestically in the United States, and that is the eradication of domestically grown 

marijuana in the national force.. .. We actually need people to go in, fly over them and locate them, 

and then go into the patches to eradicate."); id. at 242 (statement of Don Siegelman, Attorney General 

of Alabama) (“M ilitary equipment and certain personnel should be made available, under specified 

conditions, to assist civilian authorities conduct air and land marijuana spotting and eradication. M ilitary helicopters and pilots could make a significant contribution to the systematic aerial surveying of 

suspected marijuana growing areas.”); id. at 257 (statement of Edward Koch, Mayor of New York, New 

York) (“I believe that those helicopters should be flying over identifying the marijuana fields. . . . Then 

you notify the local cops, and the cops go in and make the arrest.”).

38
that FLIR surveillance of buildings on private property is authorized aerial 

reconnaissance under sections 371-374, subject only to the restrictions set 

forth in section 375.4

III.

Section 375 requires the Secretary of Defense to prescribe regulations 

ensuring that activity undertaken pursuant to sections 371 to 374 does not 

result in “direct participation by a member of the Army, Navy, Air Force, or 

Marine Corps in a search, seizure, arrest, or other similar activity.” 10 

U.S.C. § 375. The Secretary has promulgated regulations, based upon an 

earlier version of the statute, that prohibit military personnel from conducting “[a] search or seizure.” 32 C.F.R. § 213.10(a)(3).5 We understand DoD 

to take the position that the term “search” in the regulations is intended to 

have the same meaning as does the statutory term “search,” and we assume 

for purposes of this opinion that this is correct.

DoD has assumed that the statutory term “search” was intended to be 

coextensive with the same term in the Fourth Amendment and thus that the 

applicability of the section 375 prohibition to the assistance requested here 

turns on whether the FLIR surveillance constitutes a “search” within the 

meaning of the Fourth Amendment.6 Proceeding on this assumption, DoD 

has concluded that FLIR surveillance is a “search,” and therefore that section 375 prohibits the military from providing the FLIR surveillance assistance 

to civilian law enforcement agencies. We conclude from the language, structure, and legislative history of section 375 that, contrary to DoD’s assumption, 

the meaning of the term “search” was not intended to be coextensive with 

the meaning of the same term in the Fourth Amendment. Instead, when Congress used the term “search” in section 375, it intended that the term encompass 

at most only searches involving physical contact with civilians or their

4 Section 371 authorizes the Secretary of Defense to provide to civilian law enforcement officials “any 

information collected during the normal course of military training or operations that may be relevant 

to a violation of any Federal or State law.” DoD’s provision of FLIR surveillance information obtained 

during training missions in the vicinity of Wichita, Kansas, would thus appear to be separately authorized by section 371 if the requested FLIR surveillance were conducted in'the “normal course of military 

training."

!The regulations promulgated by the Department of Defense state'

Except as otherwise provided in this enclosure, the prohibition on use of military personnel 

“as a posse comitatus or otherwise to execute the laws" prohibits the following forms of 

direct assistance:

(i) Interdiction of a vehicle, vessel, aircraft or other similar activity.

(ii) A search or seizure.

(iii)An arrest, stop and frisk, or similar activity.

(iv) Use of military personnel for surveillance or pursuit of individuals, or as informants, undercover agents, investigators, or interrogators.

32 C.F.R. § 213.10(a)(3) (1991). These regulations were promulgated after chapter 18 was enacted in 

1981, but they have not been amended to achieve consistency with the statutory changes enacted in 1988 

and 1989. For example, subsection (i) of the regulations includes language that no longer appears in 10 

U.S.C. § 375.

‘ Smith Memorandum at 3, 32-38; accord Parrish Memorandum at 1; contra Hoffman Memorandum at 

2, supra.

39
property, and perhaps only searches involving physical contact that are likely to 

result in a direct confrontation between military personnel and civilians.

A.

There is no reason to assume, as a threshold matter, that the meaning of 

the term “search” in section 375 is coextensive with that of the same word 

in the Fourth Amendment. “ [0]f course words may be used in a statute in a 

different sense from that in which they are used in the Constitution.” Lamar

v. United States, 240 U.S. 60, 65 (1916); see also Verlinden B.V. v. Central

Bank of Nigeria, 461 U.S. 480, 494-95 (1983) (meaning of “arising under” 

in Article III, Section 2 differs from that of the same phrase in 28 U.S.C. § 

1331); Towne v. Eisner, 245 U.S. 418, 425 (1918) (“[I]t is not necessarily 

true that income means the same thing in the Constitution and the [Income 

Tax] Act.”). The term “search” has acquired a specialized meaning in Fourth 

Amendment jurisprudence, in light of the Amendment’s expansive purpose 

to protect all reasonable expectations of privacy. That specialized definition 

clearly encompasses activity in which there is no physical contact with or 

intrusion into private property, such as electronic wiretapping. Katz v. United

States, 389 U.S. 347 (1967).

In common parlance, however, the term usually connotes at least some 

amount of physical contact or interference. Indeed, Justice Brandeis conceded in his dissenting opinion in Olmstead v. United States, 277 U.S. 438 

(1928), which foreshadowed the Court’s decision in Katz overruling Olmstead,

that the “ordinary meaning” of “search” would encompass only activity involving a physical trespass. Id. at 476-78 (Brandeis, J., dissenting). Although 

Justice Brandeis was ultimately unsuccessful in persuading his colleagues of 

his substantive position, the most that he could say about their construction 

of the term “search” was that it was “unduly literal.”7 The “ordinary meaning” of “search” relied upon by the Court and recited by Justice Brandeis in 

Olmstead is frequently that intended by Congress. A number of statutes concerning searches by law enforcement officials, for example, seem to assume that 

a “search” involves some physical contact between law enforcement personnel 

and civilians.8 It should not be presumed, therefore, that the term “search” in 

section 375 is coextensive with the same term in the Fourth Amendment.

’ It is evident from his opinion that Justice Brandeis did not use the phrase “unduly literal" to suggest 

that the majority was mistaken as to the ordinary meaning of the term “search.” His only point was that 

adoption o f the “ordinary meaning” o f the term was inappropriate given the broad privacy protection 

purpose of the Fourth Amendment.

’ See, e.g., 7 U.S.C. § 164a (authorizing Department of Agriculture employees “to stop and, without 

warrant, to inspect, search, and examine such person, vehicle, receptacle, boat, ship, or vessel”); 18 

U.S.C. § 913 (subjecting to prosecution “[wjhoever falsely represents himself to be an officer, agent, or 

employee o f the United States, and in such assumed character arrests or detains any person or in any 

m anner searches the person, buildings, or other property of any person”); id. § 2231 (subjecting to 

prosecution “(w]hoever forcibly assaults, resists, opposes, prevents, impedes, intimidates, or interferes 

with any person authorized to serve or execute search warrants or to make searches and seizures"); id.

Continued

40
The context in which the word “search” appears in section 375 suggests 

that Congress indeed may have intended the term to refer only to searches 

involving physical contact. Section 375 employs the term “search” in association with “seizure” and “arrest,” terms which contemplate some physical 

contact with persons or property.9 If one invokes the common sense maxim 

noscitur a sociis, “[w]here any particular word is obscure or of doubtful 

meaning, taken by itself its obscurity or doubt may be removed by reference 

to associate words,” Virginia v. Tennessee, 148 U.S. 503, 519 (1893), it would 

appear that Congress intended for the term “search” in title 10 to have the 

narrow, “ordinary meaning,” rather than the meaning ascribed to the term in 

the Fourth Amendment. This suggestion is reinforced by the fact that Congress extended the prohibition in section 375 also to “other sim ilar 

activities],” that is, to other activities similar to searches, seizures, and arrests. It is apparent from this phrase that Congress regarded searches, seizures, 

and arrests as similar activities.10 Apart from the obvious fact that these are 

all law enforcement activities, one of the fundamental similarities of these 

activities is that each entails some amount of physical contact.

The intent of Congress in section 375 to prohibit only searches involving 

physical contact is particularly evident in the original version of section 375. 

As enacted in 1981, section 375 forbade direct participation by DoD personnel “in an interdiction of a vessel or aircraft, a search and seizure, arrest, or 

other similar activity.” Pub. L. No. 97-86, tit. IX, § 905(a)(1), 95 Stat. 1099 

1116 (1981) (emphasis added). The coupling of “search” and “seizure” 

through use of the conjunctive “and,” and the reference to the two as a 

single event (i.e., “a search and seizure”), strongly suggests that Congress 

was referring to searches of persons or objects that had been seized and thus 

were in the custody of law enforcement officers. Searches of seized persons 

or objects almost always involve physical contact.11

'(....continued)

§ 2232 (distinguishing between “searches" and "electronic surveillance” and prohibiting “Physical Interference With Search”); 33 U.S.C § 383 (“The commander and crew of any merchant vessel of the United 

States . . . may oppose and defend against any aggression, search, restraint, depredation, or seizure, which 

shall be attempted upon such vessel .”).

’ To “seize” is to “take hold of suddenly or forcibly" or “to take possession of by force or at will." 

Random House Dictionary o f the English Language 1734 (1987). In the law, a “seizure” generally 

requires “an intentional acquisition of physical control." Brower v. County o f Inyo, 489 U S 593, 596 

(1989). “Arrest” is most commonly defined as “the act of stopping or restraining (as from further 

motion).” Webster's Third New International Dictionary 121 (1986) The traditional meaning of “arrest" in the legal context is the seizure of a person which “eventuate[s] in a trip to the station house and 

prosecution for crime.” Terry v. Ohio, 392 U.S. 1, 16 (1968). See also Douglas v. Buder, 412 U S. 430, 

431-32 (1973); Cupp v. Murphy, 412 U S 291, 294 n 1 (1973). Both arrests and seizures thus virtually 

always entail physical contact.

l0It is possible to read the catch-all phrase “other similar activities]” to include any activity similar to 

searches, similar to seizures, or similar to arrests, in which event no inference need be drawn as to 

whether Congress regarded searches, seizures, and arrests as themselves similar to each other. This 

would be a natural reading of the phrase, however, only if the enumerated activities had nothing in 

common.

" The inference that Congress was concerned only with searches that entail some physical contact is 

strengthened by the inclusion of “search and seizure" in a series of terms with “interdiction” and "arrest,” both o f which also generally entail physical contact. See supra p. 41

41
Although Congress amended section 375 in 1989, so that it now prohibits 

participation in a “search, seizure, arrest, or similar activity,” there is no 

indication that by deleting the word “and,” Congress intended to signal a departure from the statute’s original purpose. See H.R. Conf. Rep. No. 331, 101st 

Cong., 1st Sess. 654 (1989). The 1989 amendment merely clarifies the section 

so as to prohibit military personnel from participating in searches entailing 

physical contact, even if they will not involve or lead ultimately to seizures.

B.

1.

The legislative history of chapter 18 confirms that Congress intended in 

section 375 to prohibit at most searches by the military that entail physical 

contact with civilians or their property, and perhaps only such searches that 

are likely to result in direct confrontation between military personnel and 

civilians. The history of section 375 actually begins with the Posse Comitatus Act, 18 U.S.C. § 1385, which governed military involvement in law 

enforcement activity prior to enactment of chapter 18 in 1981.12 The Posse 

Comitatus Act was adopted in 1878 in response to objections from southern 

States to United States Army participation in civilian law enforcement during Reconstruction. In the one hundred years immediately following its 

enactment, the Posse Comitatus Act was rarely the subject of litigation. To 

date, few courts have attempted to define the contours of the Act, and there 

apparently has never been a prosecution under the Act. See Posse Comitatus

Act, Hearings on H.R. 3519 Before the Subcomm. on Crime of the House

Comm, on the Judiciary, 97th Cong., 1st Sess. 21 (1981) (statement of Edward S.G. Dennis, Jr., Department of Justice) ("Posse Comitatus Hearings").

By 1948, the Posse Comitatus Act was characterized by one court as an 

“obscure and all-but-forgotten statute.” Chandler v. United States, 171 F.2d 

921, 936 (1st Cir. 1948), cert, denied, 336 U.S. 918 (1949).

The courts that confronted issues under the Posse Comitatus Act before 

1981 did not interpret the Act uniformly. Some understood the Act as a 

broad and absolute prohibition against virtually any military participation in 

civilian law enforcement activity. In two cases arising from the 1973 federal occupation of Wounded Knee, South Dakota, for example, the courts 

concluded that the mere provision of tactical advice by a military officer, if 

it were subsequently acted upon by civilians, would be unlawful. United

States v. Jaramillo, 380 F. Supp. 1375, 1381 (D.S.D. 1974), appeal dismissed,

1: The Posse Comitatus Act states:

W hoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air Force as a posse 

comitatus or otherwise to execute the laws shall be fined not more than $10,000 or imprisoned not more than two years, or both.

18 U.S.C. § 1385.

42
510 F.2d 808 (8th Cir. 1975); United States v. Banks, 383 F. Supp. 368, 375 

(D.S.D. 1974). Another court held under the Federal Tort Claims Act that 

the use of an Air Force helicopter and its personnel to aid in a search for a 

nonmilitary prison escapee was forbidden by the Posse Comitatus Act. The 

court emphasized that “[t]he innocence and harmlessness of the particular 

use of the Air Force in the present case [and] the dissimilarity of that use to 

the uses that occasioned the enactment . . . are irrelevant to the operation of 

a statute that is absolute in its command and explicit in its exceptions.” 

Wrynn v. United State, 200 F. Supp. 457, 465 (E.D.N.Y. 1961).

Other courts, however, concluded that the Posse Comitatus Act permitted 

military personnel to offer certain forms of “passive” or “nonauthoritarian” 

assistance to civilians. In another Wounded Knee case, the court interpreted 

the Act to prohibit the military from “actively performing direct law enforcement duties,” but to allow a “passive role which might indirectly aid 

[law enforcement].” United States v. Red Feather, 392 F. Supp. 916, 924-25 

(D.S.D. 1975). This court concluded that military involvement in the arrest 

of a person, seizure of evidence, search of a person, or search of a building 

constituted impermissible “direct” aid, but that tactical advice, training, and 

aerial photographic reconnaissance flights were “indirect” assistance permitted by the Act. Id.

A second court concluded after transfer of the Red Feather case that the 

Posse Comitatus Act prohibited only military activity “which is regulatory, 

prescriptive or compulsory in nature, and causes the citizens to be presently 

or prospectively subject to regulations, proscriptions, or compulsions imposed by military authority.” United States v. McArthur, 419 F. Supp. 186, 

194 (D.N.D. 1975), a ff’d sub nom., United States v. Casper, 541 F.2d 1275 

(8th Cir. 1976), cert, denied, 430 U.S. 970 (1977). The court believed that 

the Act did not outlaw “the borrowing of highly skilled personnel, like pilots 

and highly technical equipment like aircraft and cameras, for a specific, 

limited, temporary purpose.” Id. This Office, in 1978, endorsed the common points of the analyses in Red Feather and McArthur, concluding that 

military assistance in civilian law enforcement does not violate the Posse 

Comitatus Act where “there is no contact with civilian targets of law enforcement, no actual or potential use of military force, and no military control 

over the actions of civilian officials.” Letter for Deanne Siemer, General Counsel, Department of Defense, from Mary Lawton, Deputy Assistant Attorney 

General, Office of Legal Counsel at 13 (Mar. 24, 1978) (“Lawton Letter”).

In the wake of this series of decisions, there understandably was substantial confusion over the kinds of assistance that the military could provide to 

civilian law enforcement officials.

2.

Congress addressed the confusion that had arisen and clarified the boundaries of perm issible DoD law enforcement activity in 1981 through

43
amendments to chapter 18. H.R. Rep. No. 71, 97th Cong., 1st Sess., pt. 2, at 

3 (1981) (“ 1981 House Report”); S. Rep. No. 58, 97th Cong., 1st Sess. 148 

(1981). It is evident from the legislative history of these amendments that 

Congress intended to codify the distinction — articulated by the district 

court in United States v. R ed Feather — between “indirect passive” assistance and “direct active” involvement in law enforcement activity. Edward 

D ennis, testifying on behalf of the Department of Justice, stated the 

Department’s view that “the principle which is put forth in the statutes is 

that the armed services would be called upon to lend indirect and passive 

forms of assistance to civilian law enforcement.” Posse Comitatus Hearings, at 21. An expert on military-civilian relations, Professor Christopher 

Pyle, objected strenuously to the Red Feather analysis, but acknowledged 

that “[i]t is not difficult to see how the proposals currently before the Subcommittee build upon this opinion.” Id. at 42. And Rear Admiral Donald 

Thompson of the Coast Guard reported that the Navy relied on the Wounded 

Knee cases to “permit[] aerial surveillance or photo-reconnaissance missions in support of law enforcement activities on a not-to-interfere basis.” 

Id. at 49.

The committee reports from the House Judiciary Committee and the Conference Committee are relatively clear that Congress intended to adopt the 

Red Feather passive-active distinction. The committee report on the House 

bill, from which the authority granted in section 374 derives, rejected the 

absolutist view of the Posse Comitatus Act taken by the courts in United

States v. Jaramillo and United States v. Banks, stating that those decisions 

“serve to illustrate the confusion regarding the Act and the problems that 

result when it is too mechanically applied.” 1981 House Report, at 6. The 

House committee referred more favorably to the conclusion of the Red Feather

court that only “the direct active use of Army or Air Force personnel” was 

prohibited, id., and the Conference Committee eventually provided in section 375 for restrictions only “on the direct participation of military personnel 

in law enforcement activities.” 1981 Conference Report at 121.

Significantly, Congress understood Red Feather to prohibit only activity 

that entailed direct, physical confrontation between military personnel and 

civilians. During the hearings, Representative Hughes, Chairman of the Subcommittee on Crime, observed to William H. Taft IV, General Counsel of 

the Department of Defense:

I can understand where you might have to have military personnel, actually operate [in a law enforcement capacity] under 

given circumstances. I understand that. But that is a long 

way from giving them the authority to make an arrest or to 

make a seizure.

An assist, as opposed to a military person making an arrest 

or participating in a seizure is an important distinction.

44
Posse Comitatus Hearings, at 28. During the same exchange, Mr. Taft endorsed that prohibition on direct participation by military personnel in arrests 

or seizures, and presented his view of the passive-active principle: “[I]t is 

the arrests and the seizures, and active — putting, really, into a confrontation, an immediate confrontation, the military and a violator o f a civilian

statute, that causes us the greatest concern.” Id. at 30 (emphasis added).13

Congress’ concern with confrontation between military personnel and civilians is also apparent from the discussions over the provisions of the original 

section 374(c). That section authorized the use of military personnel to 

operate equipment outside the land area of the United States only in certain 

emergencies where the Attorney General and the Secretary of Defense jointly 

determine that an emergency exists. These procedural safeguards were incorporated because “[t]he conferees were concerned that [the] use of military 

personnel in such operations had the potential fo r placing such personnel in

confrontational situations." 1981 Conference Report at 120 (emphasis added).

In sum, in codifying the Red Feather passive-active participation distinction, Congress “maximize[d] the degree of cooperation between the military 

and civilian law enforcement,” 1981 House Report at 3, while carefully preventing the direct, physical confrontation between military personnel and 

civilians which it believed would “fundamentally alter the nature of the 

relationship between the military and civilian society.” Id. at l l . 14

3.

In 1988, Congress enacted amendments to chapter 18 which further underscore that the purpose of section 375 was to codify the Red Feather

distinction between “passive” and “active” assistance and thus to prohibit 

direct interface between military forces and civilians. National Defense 

Authorization Act, Fiscal Year 1989, Pub. L. No. 100-456, § 1104, 102 Stat. 

1918, 2045 (1988). Specifically, Congress deleted the ban in section 375 on 

participation in “an interdiction of a vessel or aircraft,” because that phrase 

had been understood to prohibit activities which did not involve physical 

confrontation between the military and civilians. The Conference Report 

explains:

The conferees deleted the term “interdiction of a vessel or 

aircraft,” which is set forth in current law, because the term

“interdiction ” has acquired a meaning that includes detection

and monitoring as well as a physical interference with the

13 This colloquy caused Representative Hughes to propose language, which was eventually incorporated into section 374(b), that allows DoD personnel to operate or assist in operating equipment for law 

enforcement purposes. Id. at 29.

14 Some activities prohibited under the Red Feather analysis, such as searches of buildings and seizures 

of evidence, do not necessarily entail confrontations with civilians. To the extent that such searches are 

prohibited under section 375, this reflects Congress’ concern that in carrying out such activities, military 

personnel likely would be placed in a confrontational posture with civilians.

45
movement o f a vessel or aircraft. The conferees emphasize, 

however, that they do not intend by this action to authorize 

military personnel to interrupt the passage of a vessel or aircraft except as otherwise authorized by law.

1988 Conference Report at 452 (1988) (emphasis added).

As part of the 1988 revision, Congress also amended section 374 to authorize DoD personnel to operate equipment outside the United States for 

the purpose of transporting civilian law enforcement officials. 10 U.S.C. § 

372(b). This authority, however, was expressly made subject to joint approval by the Secretary of Defense, the Attorney General, and the Secretary 

of State “because of the potential fo r involving DOD personnel in a direct

law enforcement confrontation, even though their role is designed for logistical support.” 1988 Conference Report at 452 (emphasis added). Finally, a 

new subsection (c) of section 374 was added to permit the Secretary of 

Defense to make DoD personnel available to civilian law enforcement officials for other purposes, but “only to the extent that such support does not 

involve direct participation by such personnel in a civilian law enforcement 

operation.” Id. § 374(c). In a telling explanation of how Congress understood the prohibition in subsection 374(c) on “direct participation . . . in a 

civilian law enforcement operation,” the Conference Report stated that “[t]o 

the extent that transportation of law enforcement officials or use of military 

officials does not reasonably raise the possibility o f a law enforcement confrontation, such assistance may be provided in the United States under 

subsection (c).” 1988 Conference Report at 452 (emphasis added).15

Accordingly, we conclude that Congress intended section 375 to prohibit 

at most military participation in searches involving physical contact with civilians or their property, and perhaps only such searches that are likely to result in 

direct, physical confrontation between military personnel and civilians.16

15 Two recent opinions o f this Office have concluded, based largely on this legislative history, that 

Congress intended in section 375 to bar only the exercise of military authority in contexts where there 

are likely to be direct confrontations with civilians. Use o f Navy Drug-Detecting Dogs by Civilian

Postal Inspectors, 13 Op. O.L.C. 312 (1989); Use o f Department o f Defense Drug-Detecting Dogs to

A id in Civilian Law Enforcement, 13 Op. O.L.C. 185 (1989).

'‘ Because FLIR aerial reconnaissance is authorized by section 374 and not prohibited by section 375, it 

cannot be prohibited by the Posse Comitatus Act. That Act, by terms, does not apply to activities “expressly authorized by the Constitution or Act of Congress.” 18 U.S.C. § 1385. For the same reason, we 

need not consider whether FLIR surveillance would otherwise be permitted by the Posse Comitatus Act, 

and thus excepted from the prohibitions of section 375 by 10 U.S.C. § 378. As noted, however, this 

Office concluded in 1978 that the Posse Comitatus Act does not bar the use of military personnel in 

situations where “[t]here is no contact with civilian targets of law enforcement, no actual or potential 

use o f military force, and no military control over actions of civilian officials." Lawton Letter at 13. 

Thus, there is a substantial argument that FLIR surveillance to assist civilian law enforcement officials 

would be permitted by the Posse Comitatus Act even in the absence of section 374, and therefore could 

not be prohibited by section 375.

46
IV.

DoD’s principal argument that section 375 prohibits FLIR surveillance is 

that the term “search” in section 375 is coextensive with the term “search” 

in the Fourth Amendment. This argument rests on the unsupported assertion 

that the “usual” meaning of “search” is that ascribed to the term in the 

Fourth Amendment, see Smith Memorandum at 34, an assertion that we reject for the reasons set forth above. DoD also supports its argument with the 

general statements from the legislative history that Congress sought to ‘“ reaffirm the traditionally strong American antipathy towards the use of the military 

in the execution of civil law’” and to avoid ‘“ modification in this country’s 

long tradition of separating the military from day to day involvement in the 

execution and operation of the civilian laws.’” Smith Memorandum at 34 

(quoting 1981 House Report at 10-11). Reliance upon Congress’ reaffirmation of these traditions, however, begs the only relevant question, which is 

precisely what historical paradigm Congress sought to reaffirm. As we have 

shown, the text and history of the legislation amply demonstrate that 

tradition was essentially that military personnel should be excluded from 

participation in activities that are likely to result in direct confrontation 

with civilians.17

DoD also argues that because Congress in recent years has declined to 

authorize active military personnel to conduct searches of cargo, vehicles, 

vessels, and aircraft at points of entry into the United States, section 375 

cannot be interpreted to prohibit only activity that would result in confrontation between military personnel and civilians. Smith Memorandum at 34. 

We would not draw any inference about the meaning of the statute from 

Congress’ inaction on these proposals. See Pension Benefit Guaranty Corp.

v. The LTV Corp., 496 U.S. 633, 650 (1990); United States v. Wise, 370 U.S. 

405, 411 (1962). In any event, an interpretation of section 375 that precluded border searches could well be consistent with our analysis, because 

such searches generally would require use of the military in circumstances 

likely to result in physical contact or in confrontations with civilians.

Finally, if DoD’s interpretation of section 375 were correct, then section 

375 would prohibit much of the assistance to civilian law enforcement that is 

authorized under section 374. Section 375 forbids direct participation not only 

in searches, seizures, and arrests, but also in “other similar activity.” If aerial 

reconnaissance flights over private lands using FLIR technology constitute

17 DoD acknowledges in a footnote that “[t]he Red Feather test was adopted . . . by the Congress in 10 

U S C § 375,” but contends that FLIR surveillance by military personnel nonetheless would violate 

section 375 because military personnel would be "actively performing direct law enforcement duties.” 

Smith Memorandum at 35 n.106 (quoting United States v Red Feather, 392 F. Supp. 916, 925 (D S.D. 

1975)). Once one concedes that Congress intended to codify in section 375 the Red Feather analysis, it 

is virtually impossible to conclude that FLIR surveillance is prohibited under the section Congress 

clearly understood Red Feather to prohibit at most only searches that involved physical contact with 

civilians or their property And the Red Feather court even stated that aerial photographic reconnaissance was not “direct” assistance of the kind prohibited by the Posse Comitatus Act. 392 F Supp. at 925.

47
“searches,” then analogous activities, such as aerial reconnaissance of open 

marijuana fields using binoculars or night-vision equipment, naked eye observ atio n s o f sm oke em issions from building rooftops, and other 

non-trespassory means of detecting and monitoring drug smuggling or production would constitute “other similar activities],” and thus be prohibited. 

See supra at p. 41 & n.l l.18 Indeed, much of the law enforcement assistance 

authorized by section 374 would be prohibited if FLIR surveillance constitutes a “search” for purposes of the statute. DoD personnel would be 

forbidden, for example, from operating equipment for detection, monitoring, 

and communication of the movement of air and sea traffic and from conducting aerial reconnaissance. 10 U.S.C. § 374(b)(2). Congress obviously 

did not intend to forbid in section 375 the activity that it authorized in 

section 374. It is evident therefore that the term “search” in section 375 

cannot include FLIR surveillance.

CONCLUSION

We believe that the language, structure, and history of section 375 together convincingly demonstrate that Congress intended to prohibit at most 

searches by the military that entail physical contact with civilians or their 

property, and perhaps only searches entailing physical contact that are likely 

to result in a direct confrontation between military personnel and civilians. 

Because FLIR surveillance does not constitute even a search involving physical contact with civilians or their property, we conclude that DoD personnel 

are authorized by section 374(b)(2)(B) to conduct FLIR surveillance of buildings on private property, even assuming that the surveillance constitutes a 

search for purposes of the Fourth Amendment.19

J. MICHAEL LUTTIG 

Assistant Attorney General

Office o f Legal Counsel

18 DoD apparently would confine the prohibition on “other similar activity” to Fourth Amendment 

searches, and it would not construe section 373 to ban other activities permitted by section 374. Even 

accepting D oD ’s assumption that FLIR surveillance constitutes a Fourth Amendment search, however, 

this simply is not a permissible construction of the text, because it would render the general words 

“other sim ilar activity” meaningless

19 DoD has not asked us to address, and we do not address, whether FLIR surveillance constitutes a 

Fourth Amendment search. See Smith Memorandum at 3.

48