Cybertelecom Federal Internet Law & Policy An Educational Project

4th A :: Exceptions :: Consent

Derived From: Searching and Seizing Computers and Obtaining Electronic Evidence in Criminal Investigations Computer Crime and Intellectual Property Section, Criminal Division, DOJ (2009) (Remember: This is a rendition of the state of the law from law enforcement and reflects their views)

C. Exceptions to the Warrant Requirement in Cases Involving Computers

See ECPA Exceptions

Warrantless searches that intrude upon a reasonable expectation of privacy will comply with the Fourth Amendment if they fall within an established exception to the warrant requirement. Cases involving computers often raise questions relating to how these "established" exceptions apply to new technologies.

1. Consent

Agents may search a place or object without a warrant or even probable cause if a person with authority has voluntarily consented to the search. See Schneckloth v. Bustamonte, 412 U.S. 218, 219 (1973). The authority to consent may be actual or apparent. See United States v. Buckner, 473 F.3d 551, 555 (4th Cir. 2007). The consent may be explicit or implicit. See United States v. Milian- Rodriguez, 759 F.2d 1558, 1563-64 (11th Cir. 1985). Whether consent was voluntarily given is a question of fact that the court must decide by considering the totality of the circumstances. While no single aspect controls the result, the Supreme Court has identified the following important factors: the age, education, intelligence, physical and mental condition of the person giving consent; whether the person was under arrest; and whether the person had been advised of his right to refuse consent. See Schneckloth, 412 U.S. at 226-27. The government carries the burden of proving that consent was voluntary. See United States v. Matlock, 415 U.S. 164, 177 (1974); Buckner, 473 F.3d at 554.

In computer crime cases, two consent issues arise particularly often. First, when does a search exceed the scope of consent? For example, when a target consents to the search of a location, to what extent does the consent authorize the retrieval of information stored in computers at the location? Second, who is the proper party to consent to a search? Do roommates, friends, and parents have the authority to consent to a search of another person's computer files?

Finally, consent to search may be revoked "prior to the time the search is completed." United States v. Lattimore, 87 F.3d 647, 651 (4th Cir. 1996) (quoting 3 Wayne R. LaFave, Search and Seizure § 8.2(f ), at 674 (3d ed. 1996)). When agents obtain consent to remove computers for off-site review and analysis, the time required for review can be substantial. In such cases, law enforcement should keep in mind that before incriminating evidence is found, the consent may be revoked. In cases involving physical documents obtained by consent, courts have allowed the government to keep copies of the documents made by the government prior to the revocation of consent, but they have forced the government to return copies made after consent was revoked. See Mason v. Pulliam, 557 F.2d 426, 429 (5th Cir. 1977); Vaughn v. Baldwin, 950 F.2d 331, 334 (6th Cir. 1991). There is little reason for courts to distinguish copying paper documents from copying hard drives, and one district court recently stated that a defendant who revoked the consent to search his computer retained no reasonable expectation of privacy in a mirror image copy of his hard drive made by the FBI. See United States v. Megahed, 2009 WL 722481, at *3 (M.D. Fla. Mar. 18, 2009).

a. Scope of Consent

"The scope of a consent to search is generally defined by its expressed object, and is limited by the breadth of the consent given." United States v. Pena, 143 F.3d 1363, 1368 (10th Cir. 1998) (internal quotation marks omitted). The standard for measuring the scope of consent under the Fourth Amendment is objective reasonableness: "[W]hat would the typical reasonable person have understood by the exchange between the [agent] and the [person granting consent]?" Florida v. Jimeno, 500 U.S. 248, 251 (1991). This requires a fact-intensive inquiry into whether it was reasonable for the agent to believe that the scope of consent included the items searched. Id. Of course, when the limits of the consent are clearly given, either before or during the search, agents must respect these bounds. See Vaughn v. Baldwin, 950 F.2d 331, 333-34 (6th Cir. 1991).

Computer cases often raise the question of whether general consent to search a location or item implicitly includes consent to access the memory of electronic storage devices encountered during the search. In such cases, courts look to whether the particular circumstances of the agents' request for consent implicitly or explicitly limited the scope of the search to a particular type, scope, or duration. Because this approach ultimately relies on fact-driven notions of common sense, results reached in published opinions have hinged upon subtle (if not entirely inscrutable) distinctions. Compare United States v. Reyes, 922 F. Supp. 818, 834 (S.D.N.Y. 1996) (consent to "look inside" a car included consent to retrieve numbers stored inside pagers found in car's back seat), with United States v. Blas, 1990 WL 265179, at *20 (E.D. Wis. Dec. 4, 1990) (consent to "look at" a pager did not include consent to activate pager and retrieve numbers, because looking at pager could be construed to mean "what the device is, or how small it is, or what brand of pager it may be"). See also United States v. Carey, 172 F.3d 1268, 1274 (10th Cir. 1999) (reading written consent form extremely narrowly, so that consent to seizure of "any property" under the defendant's control and to "a complete search of the premises and property" at the defendant's address merely permitted the agents to seize the defendant's computer from his apartment, not to search the computer off-site because it was no longer located at the defendant's address); United States v. Tucker, 305 F.3d 1193, 1202 (10th Cir. 2002) (allowing computer search pursuant to parole agreement allowing search of "any other property under [defendant's] control"); United States v. Lemmons, 282 F.3d 920, 924-25 (7th Cir. 2002) (defendant expanded initial consent to search of cameras and recordings to include computer files when he invited officer to look at computer and failed to object to officer's search for pornographic images). Prosecutors can strengthen their argument that the scope of consent included consent to search electronic storage devices by relying on analogous cases involving closed containers. See, e.g., United States v. Al-Marri, 230 F. Supp. 2d 535, 540-41 (S.D.N.Y. 2002) (upholding search of computer in residence and citing principle that separate consent to search closed container in fixed premises is unnecessary); United States v. Galante, 1995 WL 507249, at *3 (S.D.N.Y. Aug. 25, 1995) (general consent to search car included consent to have officer access memory of cellular telephone found in the car, in light of circuit precedent involving closed containers); Reyes, 922 F. Supp. at 834.

When agents obtain consent for one reason but then conduct a search for another reason, they should be careful to make sure that the scope of consent encompasses their actual search. For example, in United States v. Turner, 169 F.3d 84 (1st Cir. 1999), the First Circuit suppressed images of child pornography found on computers after agents procured the defendant's consent to search his property for other evidence. In Turner, detectives searching for physical evidence of an attempted sexual assault obtained written consent to search the defendant's "premises" and "personal property." Before the defendant signed the consent form, the detectives discovered a large knife and blood stains in his apartment, and they explained to him that they were looking for more evidence of the assault that the suspect might have left behind. See id. at 85-86. While several agents searched for physical evidence, one detective searched the contents of the defendant's personal computer and discovered stored images of child pornography. The defendant was thereafter charged with possessing child pornography. On interlocutory appeal, the First Circuit held that the search of the computer exceeded the scope of consent and suppressed the evidence. According to the Court, the detectives' statements that they were looking for signs of the assault limited the scope of consent to the kind of physical evidence that an intruder might have left behind. See id. at 88. By transforming the search for physical evidence into a search for computer files, the detective exceeded the scope of consent. See id.; see also Carey, 172 F.3d at 1277 (Baldock, J., concurring) (concluding that agents exceeded scope of consent by searching computer after defendant signed broadly-worded written consent form, because agents told defendant that they were looking for drugs and drugrelated items rather than computer files containing child pornography) (citing Turner). Of course, as with other scope-of-consent cases, cases analyzing the reason for a search are fact specific, and courts' interpretations of the scope of consent are not always narrow. See United States v. Marshall, 348 F.3d 281, 287-88 (1st Cir. 2003) (finding that consent to search for "stolen items" did not preclude seizing and viewing video tapes where video equipment, but not video tapes, were reported stolen); United States v. Raney, 342 F.3d 551, 556- 58 (7th Cir. 2003) (finding consent to search for "materials in the nature of " child exploitation and child erotica was broad enough to encompass search of homemade adult pornography where the defendant had expressed an intent to make similar homemade pornography with a minor).

Finally, the scope of consent usually relates to the target item, location, and purpose of the search, rather than the search methodology used. For example, in United States v. Brooks, 427 F.3d 1246 (10th Cir. 2005), an agent received permission to conduct a "complete search" of the defendant's computer for child pornography. The agent explained that he would use a "pre-search" disk to find and display image files, allowing the agent to easily ascertain whether any images contained child pornography. Id. at 1248. When the disk, for unexplained reasons, failed to function, the agent conducted a manual search for image files, eventually discovering several pieces of child pornography. Id. Although the agent ultimately used a different search methodology than the one he described to the defendant, the Court approved the manual search because it did not exceed the scope of the described disk search. Id. at 1249-50. See also United States v. Long, 425 F.3d 482, 487 (7th Cir. 2005) (finding that agent's use of "sophisticated" Encase Forensic software did not exceed scope of consent to search laptop).

Because the decisions evaluating the scope of consent to search computers have reached sometimes unpredictable results, investigators should indicate the scope of the search explicitly when obtaining a suspect's consent to search a computer. Moreover, investigators who have seized a computer based on consent and who have developed probable cause may consider obviating concerns with either the scope of consent or revocation of consent by obtaining a search warrant. For a sample consent to search form, see Appendix J.

b. Third Party Consent

i. General Principles

It is common for several people to use or own the same computer equipment. If any one of those people gives permission to search for data, agents may generally rely on that consent, so long as the person has authority over the computer. In such cases, all users have assumed the risk that a co-user might discover everything in the computer and might also permit law enforcement to search this "common area" as well.

The watershed case in this area is United States v. Matlock, 415 U.S. 164 (1974). In Matlock, the Supreme Court stated that one who has "common authority" over premises or effects may consent to a search even if an absent co-user objects. Id. at 171. According to the Court, the common authority that establishes the right of third-party consent requires

mutual use of the property by persons generally having joint access or control for most purposes, so that it is reasonable to recognize that any of the co-inhabitants has the right to permit the inspection in his own right and that the others have assumed the risk that one of their number might permit the common area to be searched.

Id. at 171 n.7.

Under the Matlock approach, a private third party may consent to a search of property under the third party's joint access or control. Agents may view what the third party may see without violating any reasonable expectation of privacy so long as they limit the search to the zone of the consenting third party's common authority. See United States v. Jacobsen, 466 U.S. 109, 119-20 (1984) (noting that the Fourth Amendment is not violated when a private third party invites the government to view the contents of a package under the third party's control). This rule often requires agents to inquire into third parties' rights of access before conducting a consent search and to draw lines between those areas that fall within the third party's common authority and those areas outside of the third party's control. See United States v. Block, 590 F.2d 535, 541 (4th Cir. 1978) (holding that a mother could consent to a general search of her 23-year-old son's room, but could not consent to a search of a locked footlocker found in the room).

Co-users of a computer will generally have the ability to consent to a search of its files under Matlock. See United States v. Smith, 27 F. Supp. 2d 1111, 1115-16 (C.D. Ill. 1998) (concluding that a woman could consent to a search of her boyfriend's computer located in their house and noting that the boyfriend had not password-protected his files). However, when an individual protects her files with passwords and has not shared the passwords with others who also use the computer, the Fourth Circuit has held that the authority of those other users to consent to search of the computer will not extend to the password-protected files. See Trulock v. Freeh, 275 F.3d 391, 403 (4th Cir. 2001) (analogizing password-protected files to locked footlockers inside a bedroom, which the court had previously held to be outside the scope of common authority consent). Nevertheless, specific facts may overcome an individual's expectation of privacy even in password-protected files. In United States v. Buckner, 407 F. Supp. 2d 777 (W.D. Va. 2006), the Court held that the defendant's wife could validly consent to a search of the family computer, including her husband's password-protected files. The Court distinguished Trulock by noting that the computer was leased solely in the wife's name, the allegedly fraudulent activity that provoked the search had occurred through accounts in the wife's name, the computer was located in a common area of the house, none of the files were encrypted, and the computer was on even though the husband had apparently fled the area. Id. at 780-81. Furthermore, if the co-user has been given the password by the suspect, then she probably has the requisite common authority to consent to a search of the files under Matlock. See United States v. Murphy, 506 F.2d 529, 530 (9th Cir. 1974) (per curiam) (concluding that an employee could consent to a search of an employer's locked warehouse because the employee possessed the key, and finding "special significance" in the fact that the employer had himself delivered the key to the employee).

As a practical matter, agents may have little way of knowing the precise bounds of a third party's common authority when the agents obtain thirdparty consent to conduct a search. When queried, consenting third parties may falsely claim that they have common authority over property. In Illinois v. Rodriguez, 497 U.S. 177 (1990), the Supreme Court held that the Fourth Amendment does not automatically require suppression of evidence discovered during a consent search when it later comes to light that the third party who consented to the search lacked the authority to do so. See id. at 188-89. Instead, the Court held that agents can rely on a claim of authority to consent if based on "the facts available to the officer at the moment, . . . a man of reasonable caution . . . [would believe] that the consenting party had authority" to consent to a search of the premises. Id. (internal quotation marks omitted) (quoting Terry v. Ohio, 392 U.S. 1, 21-22 (1968)). When agents reasonably rely on apparent authority to consent, the resulting search does not violate the Fourth Amendment. For example, in United States v. Morgan, 435 F.3d 660 (6th Cir. 2006), investigators received consent from the defendant's wife to search a computer located in the common area of the home. The wife told police that she had access to the computer, that neither she nor her husband used individual usernames or passwords, and that she had recently installed spyware on the computer to monitor her husband's suspected viewing of child pornography. Id. at 663-64. She did not tell the police that she had her own, separate computer for her primary use. Id. at 662. Nevertheless, the Court found that the police could reasonably rely on her statements and conclude that she had authority to consent to the search. Id. at 664. See also United States v. Andrus, 483 F.3d 711, 720-21 (10th Cir. 2007) (holding that parent had apparent authority to consent to search of computer in room of adult child, where parent had unrestricted access to adult child's bedroom and paid for Internet access).

The Supreme Court has held, however, that investigators cannot rely on a third party's consent to search a residence when the target of the search is present and expressly objects to the search. See Georgia v. Randolph, 547 U.S. 103, 121 (2006). The court's conclusion was based on its determination that a "co-tenant wishing to open the door to a third party has no recognized authority in law or social practice to prevail over a present and objecting co-tenant." Id. at 114. Moreover, unless police remove a potential objector "for the sake of avoiding a possible objection," Randolph does not apply to "potential" objectors who have not taken part in the consent colloquy, even if the potential objector is nearby. Id. at 121. For example, in United States v. Hudspeth, 518 F.3d 954 (8th Cir. 2008) (en banc), officers arrested the defendant at his workplace for possession of child pornography, and the defendant refused to consent to a search of his home. Nevertheless, his wife subsequently consented to a search of a computer in their home. The Eighth Circuit upheld the search, explaining that "unlike Randolph, the officers in the present case were not confronted with a 'social custom' dilemma, where two physically present co-tenants have contemporaneous competing interests and one consents to a search, while the other objects." Id. at 960. See also United States v. Crosbie, 2006 WL 1663667, at *2 (S.D. Ala. June 9, 2006) (defendant's wife's consent to computer search was valid even though wife had ordered her husband out of the house, thus depriving him of the "opportunity to object").

ii. Spouces and Domestic Partners

Absent an affirmative showing that the consenting spouse has no access to the property searched, the courts generally hold that either spouse may consent to a search of all of the couple's property. See, e.g., Trulock v. Freeh, 275 F.3d 391, 398, 403-04 (4th Cir. 2001) (holding that woman did not have authority to consent to search of computer files of the man with whom she lived, when she had told agents that she did not know the password to access his files); United States v. Duran, 957 F.2d 499, 504-05 (7th Cir. 1992) (concluding that wife could consent to search of barn she did not use because husband had not denied her the right to enter barn); United States v. Long, 524 F.2d 660, 661 (9th Cir. 1975) (holding that wife who had left her husband could consent to search of jointly-owned home even though husband had changed the locks). For example, in United States v. Smith, 27 F. Supp. 2d 1111 (C.D. Ill. 1998), a man named Smith was living with a woman named Ushman and her two daughters. When allegations of child molestation were raised against Smith, Ushman consented to the search of his computer, which was located in the house in an alcove connected to the master bedroom. Although Ushman used Smith's computer only rarely, the district court held that she could consent to the search of Smith's computer. Because Ushman was not prohibited from entering the alcove and Smith had not password-protected the computer, the court reasoned, she had authority to consent to the search. See id. at 1115- 16. U.S. v. Nichols, 2009 U.S. App. LEXIS 16724 (8th Cir. July 29, 2009) (Live-in girlfriend had complete access to house, including computer that was searched, and therefore could consent to search). Even if she lacked actual authority to consent, the court added, she had apparent authority to consent. See id. at 1116 (citing Illinois v. Rodriguez, 497 U.S. 177 (1990)).

• US v King, 3rd Cir Apr 30, 2010 (" The principal question of precedential import is whether the rule of law established in Georgia v. Randolph, 547 U.S. 103, 122-23, 126 S.Ct. 1515, 164 L.Ed.2d 208 (2006), viz., that a present and objecting resident can override another resident's consent to search a home, applies to the seizure of a computer. We hold that it does not. ")

iii. Parents

In some computer crime cases, the perpetrators are relatively young and reside with their parents. When the perpetrator is a minor, parental consent to search the perpetrator's property and living space will almost always be valid. See 3 Wayne LaFave, Search and Seizure: A Treatise on the Fourth Amendment § 8.4(b) at 283 (2d ed. 1987) (noting that courts have rejected "even rather extraordinary efforts by [minor] child[ren] to establish exclusive use.").

When the sons and daughters who reside with their parents are legal adults, however, the issue is more complicated. Under Matlock, it is clear that parents may consent to a search of common areas in the family home regardless of the perpetrator's age. See, e.g., United States v. Lavin, 1992 WL 373486, at *6 (S.D.N.Y. Nov. 30, 1992) (recognizing right of parents to consent to search of basement room where son kept his computer and files). When agents would like to search an adult child's room or other private areas, however, agents cannot assume that the adult's parents have authority to consent. Although courts have offered divergent approaches, they have paid particular attention to three factors: the suspect's age; whether the suspect pays rent; and whether the suspect has taken affirmative steps to deny his or her parents access to the suspect's room or private area. When suspects are older, pay rent, and/ or deny access to parents, courts have generally held that parents may not consent. See United States v. Whitfield, 939 F.2d 1071, 1075 (D.C. Cir. 1991) ("cursory questioning" of suspect's mother insufficient to establish right to consent to search of 29-year-old son's room); United States v. Durham, 1998 WL 684241, at *4 (D. Kan. Sept. 11, 1998) (mother had neither apparent nor actual authority to consent to search of 24-year-old son's room, because son had changed the locks to the room without telling his mother, and son also paid rent for the room). In contrast, parents usually may consent if their adult children do not pay rent, are fairly young, and have taken no steps to deny their parents access to the space to be searched. See United States v. Andrus, 483 F.3d 711, 713, 720-21 (10th Cir. 2007) (parent had apparent authority to consent to search of computer in room of 51-year-old son who did not pay rent, where parent had unrestricted access to adult child's bedroom and paid for Internet access); United States v. Rith, 164 F.3d 1323, 1331 (10th Cir. 1999) (suggesting that parents were presumed to have authority to consent to a search of their 18-year-old son's room because he did not pay rent); United States v. Block, 590 F.2d 535, 541 (4th Cir. 1978) (mother could consent to police search of 23- year-old son's room when son did not pay rent).

iv. Computer Repair Technicians

As discussed above in Section B.4, computer searches by repairman prior to contact with law enforcement are private searches and do not implicate the Fourth Amendment. Most commonly, law enforcement will use information revealed through a repairman's private search as a basis to secure a warrant for a full search of the computer. In some cases, however, law enforcement officers have relied on the consent of the repairman as the basis for a search of the computer that exceeds the scope of the initial private search. District courts have split on whether computer repairmen have the authority to authorize such searches. Compare United States v. Anderson, 2007 WL 1121319, at *6 (N.D. Ind. Apr. 16, 2007) (technicians had "actual and apparent authority" to consent to a search of computer brought in for repair because they had authority to access the computer), with United States v. Barth, 26 F. Supp. 2d 929, 938 (W.D. Tex. 1998) (repairman lacked actual or apparent authority to consent to search of hard drive because the defendant had given the hard drive to the technician only for a limited purpose unrelated to the specific files and only for a limited period of time).

v. System Administrators

Computer network accounts, including the accounts provided by private employers to their employees, by government entities to public employees, and by large commercial service providers to their customers, often contain information relevant to criminal investigations. When investigators suspect that a computer network account contains relevant evidence, they may want to know whether the network's owner or manager has authority to voluntarily disclose information related to the account. As a practical matter, every computer network is managed by a "system administrator" or "system operator" whose job is to keep the network running smoothly, monitor security, and repair the network when problems arise. System operators have "root level" access to the systems they administer, which effectively grants them master keys to open any account and read any file on their systems. However, whether a system administrator (generally at the direction of an appropriate supervisory official) may voluntarily consent to disclose information from or regarding a user's account varies based on whether the network belongs to a communication service provider, a private business, or a government entity.

Regarding public commercial communication service providers (such as Google or Yahoo!), the primary barrier to voluntary disclosure by the service provider is statutory, not constitutional. As discussed in Chapter 3, any attempt to obtain a system administrator's consent to disclose information regarding an account must comply with the Stored Communications Act ("SCA"), 18 U.S.C. §§ 2701-2712. Section 2702 of the SCA prohibits public service providers from voluntarily disclosing to the government information pertaining to their customers except in certain specified situations-which often track Fourth Amendment exceptions-such as with the consent of the user, to protect the service provider's rights and property, or in an emergency. See Chapter 3.E, infra. Significantly for Fourth Amendment purposes, commercial service providers typically have terms of service that confirm their authority to access information stored on their systems, and such terms of service may establish a service provider's common authority over their users' accounts. See United States v. Young, 350 F.3d 1302, 1308-09 (11th Cir. 2003) (holding that Federal Express's terms of service, which authorized it to inspect packages, gave it common authority to consent to a government search of a package); see also United States v. Beckett, 544 F. Supp. 2d 1346, 1350 (S.D. Fla. 2008) ("where service providers have an agreement to share information under circumstances similar to those in our case (for investigation, to cooperate with law enforcement, and to take legal action), there is no objectively reasonable expectation of privacy and therefore no Fourth Amendment protection for subscriber information"). But see Quon v. Arch Wireless Operating Co., 529 F.3d 892, 904-08 (9th Cir. 2008) (finding government employee had reasonable expectation of privacy in pager messages stored by provider of communication service based on "informal policy that the text messages would not be audited").

As discussed more fully in Section D.1.b below, private-sector employers generally have broad authority to consent to searches in the workplace, and this authority extends to workplace networks. For example, in United States v. Ziegler, 474 F.3d 1184 (9th Cir. 2007), the Ninth Circuit held that an employer could consent to a search of the computer it provided to an employee and stated that "the computer is the type of workplace property that remains within the control of the employer even if the employee has placed personal items in it." Id. at 1191 (internal quotation marks omitted). Thus, law enforcement can generally rely on the consent of an appropriate manager to search a private workplace network. In contrast, as discussed in Section D.2 below, the Fourth Amendment rules for government computer networks differ significantly from the rules that apply to private networks. Searches of government computer networks are not evaluated under Matlock; instead, they are evaluated under the standards of O'Connor v. Ortega, 480 U.S. 709 (1987).

c. Implied Consent

Individuals often enter into agreements with the government in which they waive some of their Fourth Amendment rights. For example, prison guards may agree to be searched for drugs as a condition of employment, and visitors to government buildings may agree to a limited search of their person and property as a condition of entrance. Similarly, users of computer systems may waive their rights to privacy as a condition of using the systems. When individuals who have waived their rights are then searched and challenge the searches on Fourth Amendment grounds, courts typically focus on whether the waiver eliminated the individual's reasonable expectation of privacy against the search. See, e.g., United States v. Simons, 206 F.3d 392, 398 (4th Cir. 2000) (government employee had no reasonable expectation of privacy in computer in light of computer use policy); American Postal Workers Union, Columbus Area Local AFL-CIO v. United States Postal Service, 871 F.2d 556, 559-61 (6th Cir. 1989) (postal employees retained no reasonable expectation of privacy in government lockers after signing waivers). For an expanded discussion of workplace searches, see Section D below.

A few courts have approached the same problem from a slightly different direction and have asked whether the waiver established implied consent to the search. According to the doctrine of implied consent, consent to a search may be inferred from an individual's conduct. For example, in United States v. Ellis, 547 F.2d 863 (5th Cir. 1977), a civilian visiting a naval air station agreed to post a visitor's pass on the windshield of his car as a condition of bringing the car on the base. The pass stated that "[a]cceptance of this pass gives your consent to search this vehicle while entering, aboard, or leaving this station." Id. at 865 n.1. During the visitor's stay on the base, a station investigator who suspected that the visitor had stored marijuana in the car approached the visitor and asked him if he had read the pass. After the visitor admitted that he had, the investigator searched the car and found 20 plastic bags containing marijuana. The Fifth Circuit ruled that the warrantless search of the car was permissible, because the visitor had impliedly consented to the search when he knowingly and voluntarily entered the base with full knowledge of the terms of the visitor's pass. See id. at 866-67.

Ellis notwithstanding, it must be noted that several circuits have been critical of the implied consent doctrine in the Fourth Amendment context. Despite the Fifth Circuit's broad construction, other courts have been reluctant to apply the doctrine absent evidence that the suspect actually knew of the search and voluntarily consented to it at the time the search occurred. See McGann v. Northeast Illinois Regional Commuter R.R. Corp., 8 F.3d 1174, 1180 (7th Cir. 1993) ("Courts confronted with claims of implied consent have been reluctant to uphold a warrantless search based simply on actions taken in the light of a posted notice."); Security and Law Enforcement Employees, Dist. Council 82 v. Carey, 737 F.2d 187, 202 n.23 (2d Cir. 1984) (rejecting argument that prison guards impliedly consented to search by accepting employment at prison where consent to search was a condition of employment). Absent such evidence, these courts have preferred to examine general waivers of Fourth Amendment rights solely under the reasonable-expectation-of-privacy test. See id.

C.2. Exigent Circumstances