Fourth Amendment — Exceptions to Warrant Requirement

Amdt4.6.1 Overview of Exceptions to Warrant Requirement

Although the Supreme Court stresses the importance of warrants and has repeatedly referred to searches without warrants as “exceptional,”¹ it appears that the greater number of searches, as well as the vast number of arrests, take place without warrants. The Reporters of the American Law Institute Project on a Model Code of Pre-Arraignment Procedure have noted “their conviction that, as a practical matter, searches without warrant and incidental to arrest have been up to this time, and may remain, of greater practical importance” than searches pursuant to warrants. “[T]he evidence on hand . . . compel[s] the conclusion that searches under warrants have played a comparatively minor part in law enforcement, except in connection with narcotics and gambling laws.”² Nevertheless, the Court frequently asserts that “the most basic constitutional rule in this area is that ‘searches conducted outside the judicial process, without prior approval by judge or magistrate, are per se unreasonable under the Fourth Amendment—subject only to a few specially established and well-delineated exceptions.’”³ The exceptions are said to be “jealously and carefully drawn,”⁴ and there must be “a showing by those who seek exemption . . . that the exigencies of the situation made that course imperative.”⁵ Although the record indicates an effort to categorize the exceptions, the number and breadth of those exceptions have been growing.

Amdt4.6.2 Consent Searches

Fourth Amendment rights, like other constitutional rights, may be waived, and one may consent to a search of his person or premises by officers who have not complied with the Amendment.¹ The Court, however, has insisted that the burden is on the prosecution to prove the voluntariness of the consent² and awareness of the right of choice.³ Reviewing courts must determine on the basis of the totality of the circumstances whether consent has been freely given or has been coerced. Actual knowledge of the right to refuse consent is not essential for a search to be found voluntary, and police therefore are not required to inform a person of his rights, as through a Fourth Amendment version of Miranda warnings.⁴ But consent will not be regarded as voluntary when the officer asserts his official status and claim of right and the occupant yields because of these factors.⁵ When consent is obtained through the deception of an undercover officer or an informer’s gaining admission without advising a suspect who he is, the Court has held that the suspect has simply assumed the risk that an invitee would betray him, and evidence obtained through the deception is admissible.⁶ Moreover, while the Court has appeared to endorse implied consent laws that view individuals who engage in certain regulated activities as having implicitly agreed to certain searches related to that activity and the enforcement of such laws through civil penalties,⁷ the implied consent doctrine does not extend so far as to deem individuals to have impliedly consented to a search on “pain of committing a criminal offense.”⁸

Additional issues arise in determining the validity of consent to search when consent is given not by the suspect, but by a third party. In the earlier cases, third-party consent was deemed sufficient if that party “possessed common authority over or other sufficient relationship to the premises or effects sought to be inspected.”⁹ Now, however, actual common authority over the premises is not required; it is sufficient if the searching officer had a reasonable but mistaken belief that the third party had common authority and could consent to the search.¹⁰ If, however, one occupant consents to a search of shared premises, but a physically present co-occupant expressly objects to the search, the search is unreasonable.¹¹ Common social expectations inform the analysis. A person at the threshold of a residence could not confidently conclude he was welcome to enter over the express objection of a present co-tenant. Expectations may change, however, if the objecting co-tenant leaves, or is removed from, the premises with no prospect of imminent return.¹²

Amdt4.6.3 Exigent Circumstances and Warrants

The Court has recognized “the exigencies of the situation” as an exception to the warrant requirement, which “make the needs of law enforcement so compelling that the warrantless search is objectively reasonable under the Fourth Amendment.”¹ Exigent circumstances requires a court “to examine whether an emergency justified a warrantless search in each particular case.”² The Court has identified several types of circumstances that give rise to an exigency sufficient to justify a warrantless search, including a search incident to arrest,³ law enforcement’s need to provide emergency aid,⁴ “hot pursuit” of a fleeing suspect,⁵ and the prevention of the imminent destruction of evidence.⁶ In situations absent dangerous and life-threatening circumstances, the Court recognizes that warrantless searches are permissible in circumstances where “there is a compelling need for official action and no time to secure a warrant.”⁷

The Court has refused to adopt a categorical rule as to what circumstances constitutes an exigency and, instead, applies a case-by-case analysis dependent on “all of the facts and circumstances of the particular case.”⁸ To determine whether exigent circumstances existed to justify a warrantless search, the Court “looks to the totality of circumstances.”⁹ In rendering emergency assistance, the officer must have “an objectively reasonable basis for believing” that an individual within the home was in need of immediate assistance.¹⁰ When the police, in executing a warrantless search, have not created the exigency in question, the Court has held that such “warrantless entry to prevent the destruction of evidence is reasonable and thus allowed.”¹¹ In contrast, the Court in Johnson v. United States rejected the government’s claim that exigent circumstances justified a warrantless search of an individual’s home.¹² In Johnson, the police gained entry into the suspect’s home after a “demand[ ] under color of office.”¹³ The Court, in rejecting the government’s claim that the search was conducted because of the “opium smell in the room,” held that the government offered no reason “for not obtaining a search warrant except the inconvenience to the officers and some slight delay necessary to prepare papers and present the evidence to a magistrate.”¹⁴ The Court reasoned that “[t]hese are never very convincing reasons and, in these circumstances, certainly are not enough to by-pass the constitutional requirement. No suspect was fleeing or likely to take flight. The search was of permanent premises, not of a movable vehicle. No evidence or contraband was threatened with removal or destruction, except perhaps the fumes which [the Court] suppose[d] in time would disappear.”¹⁵

In terms of determining the reasonableness for the police to proceed without a warrant when they are in hot pursuit of a suspect, the Court has held that, in such circumstances, “the need to act quickly . . . is even greater . . . while the intrusion is much less.”¹⁶ For example, the Court has held that the “Fourth Amendment does not require police officers to delay in the course of an investigation if to do so would gravely endanger their lives or the lives of others.”¹⁷ In Lange v. California, the Court reiterated that the exigent circumstances exception is generally applied on a “case-by-case basis,”¹⁸ and declined to hold that pursuing a misdemeanor suspect categorically qualifies as an exigent circumstance exception to the warrant requirement.¹⁹

Amdt4.6.4.1 Search Incident to Arrest Doctrine

The common-law rule permitting searches of the person of an arrestee as an incident to the arrest has occasioned little controversy in the Court.¹ The Court has even upheld a search incident to an illegal (albeit not unconstitutional) arrest.² The dispute has centered around the scope of the search. Because it was the stated general rule that the scope of a warrantless search must be strictly tied to and justified by the circumstances that rendered its justification permissible, and because it was the rule that the justification of a search of the arrestee was to prevent destruction of evidence and to prevent access to a weapon,³ it was argued to the Court that a search of the person of the defendant arrested for a traffic offense, which discovered heroin in a crumpled cigarette package, was impermissible, because there could have been no destructible evidence relating to the offense for which he was arrested and no weapon could have been concealed in the cigarette package. The Court rejected this argument, ruling that “no additional justification” is required for a custodial arrest of a suspect based on probable cause.⁴

The Court has disavowed a case-by-case evaluation of searches made post-arrest⁵ and instead has embraced categorical evaluations as to post-arrest searches. Thus, in Riley v. California,⁶ the Court declined to extend the holding of United States v. Robinson to the search of the digital data contained in a cell phone found on an arrestee. Specifically, the Court distinguished a search of cell phones, which contain vast quantities of personal data, from the limited physical search at issue in Robinson.⁷ Focusing primarily on the rationale that searching cell phones would prevent the destruction of evidence, the government argued that cell phone data could be destroyed remotely or become encrypted by the passage of time. The Court, however, both discounted the prevalence of these events and the efficacy of warrantless searches to defeat them. Rather, the Court noted that other means existed besides a search of a cell phone to secure the data contained therein, including turning the phone off or placing the phone in a bag that isolates it from radio waves.⁸ Because of the more substantial privacy interests at stake when digital data is involved in a search incident to an arrest and because of the availability of less intrusive alternatives to a warrantless search, the Court in Riley concluded that, as a “simple” categorical rule, before police can search a cell phone incident to an arrest, the police must “get a warrant.”⁹

Two years after Riley, the Court again crafted a new brightline rule with respect to searches following an arrest in another “situation[ ] that could not have been envisioned when the Fourth Amendment was adopted.”¹⁰ In Birchfield v. North Dakota, the Court examined whether compulsory breath and blood tests administered in order to determine the blood alcohol concentration (BAC) of an automobile driver, following the arrest of that driver for suspected “drunk driving,” are unreasonable under the search incident to arrest exception to the Fourth Amendment’s warrant requirement.¹¹ In examining laws criminalizing the refusal to submit to either a breath or blood test, similar to Riley, the Court relied on a general balancing approach used to assess whether a given category of searches is reasonable, weighing the individual privacy interests implicated by such tests against any legitimate state interests.¹² With respect to breath tests, the Birchfield Court viewed the privacy intrusions posed by such tests as “almost negligible” in that a breath test is functionally equivalent to the process of using a straw to drink a beverage and yields a limited amount of useful information for law enforcement agents.¹³ In contrast, the Court concluded that a mandatory blood test raised more serious privacy interests,¹⁴ as blood tests pierce the skin, extract a part of the subject’s body, and provide far more information than a breathalyzer test.¹⁵ Turning to the state’s interest in obtaining BAC readings for persons arrested for drunk driving, the Birchfield Court acknowledged the government’s “paramount interest” in preserving public safety on highways, including the state’s need to deter drunk driving from occurring in the first place through the imposition of criminal penalties for failing to cooperate with drunk driving investigations.¹⁶ Weighing these competing interests, the Court ultimately concluded that the Fourth Amendment permits warrantless breath tests incident to arrests for drunk driving because the “impact of breath tests on privacy is slight,” whereas the “need for BAC testing is great.”¹⁷ In so doing, the Court rejected the alternative of requiring the state to obtain a warrant prior to the administration of a BAC breath test, noting (1) the need for clear, categorical rules to provide police adequate guidance in the context of a search incident to an arrest and (2) the potential administrative burdens that would be incurred if warrants were required prior to every breathalyzer test.¹⁸ Nonetheless, the Court reached a “different conclusion” with respect to blood tests, finding that such tests are “significantly more intrusive” and their “reasonability must be judged in light of the availability of the less intrusive alternative of a breath test.”¹⁹ As a consequence, the Court held that while a warrantless breath test following a drunk-driving arrest is categorically permissible as a reasonable search under the Fourth Amendment, a warrantless blood test cannot be justified by the search incident to arrest doctrine.²⁰

However, the Justices have long found themselves in disagreement about the scope of the search incident to arrest as it extends beyond the person to the area in which the person is arrested—most commonly either his premises or his vehicle. Certain early cases went both ways on the basis of some fine distinctions,²¹ but in Harris v. United States,²² the Court approved a search of a four-room apartment pursuant to an arrest under warrant for one crime, where the search turned up evidence of another crime. A year later, in Trupiano v. United States,²³ a raid on a distillery resulted in the arrest of a man found on the premises and a seizure of the equipment; the Court reversed the conviction because the officers had had time to obtain a search warrant and had not done so. “A search or seizure without a warrant as an incident to a lawful arrest has always been considered to be a strictly limited right. It grows out of the inherent necessities of the situation at the time of the arrest. But there must be something more in the way of necessity than merely a lawful arrest.”²⁴ The Court in Lange v. California declined to classify categorically the hot pursuit of a fleeing misdemeanor suspect as an exigent circumstance justifying warrantless entry of a premise. Instead, the Court held that the need for a warrant will depend on the totality of the circumstances and a case-by-case analysis of the exigencies present “to determine whether there is a law enforcement emergency.”²⁵

The Court overruled Trupiano in United States v. Rabinowitz,²⁶ in which officers had arrested the defendant in his one-room office pursuant to an arrest warrant and proceeded to search the room completely. The Court observed that the issue was not whether the officers had the time and opportunity to obtain a search warrant but whether the search incident to arrest was reasonable. Though Rabinowitz referred to searches of the area within the arrestee’s “immediate control,”²⁷ it provided no standard by which this area was to be determined, and extensive searches were permitted under the rule.²⁸

In Chimel v. California,²⁹ however, a narrower view was asserted, the primacy of warrants was again emphasized, and a standard by which the scope of searches pursuant to arrest could be ascertained was set out. “When an arrest is made, it is reasonable for the arresting officer to search the person arrested in order to remove any weapons that the latter might seek to use in order to resist arrest or effect his escape. Otherwise, the officer’s safety might well be endangered, and the arrest itself frustrated. In addition, it is entirely reasonable for the arresting officer to search for and seize any evidence on the arrestee’s person in order to prevent its concealment or destruction. And the area into which an arrestee might reach in order to grab a weapon or evidentiary items must, of course, be governed by a like rule. A gun on a table or in a drawer in front of someone who is arrested can be as dangerous to the arresting officer as one concealed in the clothing of the person arrested. There is ample justification, therefore, for a search of the arrestee’s person and the area ‘within his immediate control’—construing that phrase to mean the area from within which he might gain possession of a weapon or destructible evidence.”

“There is no comparable justification, however, for routinely searching any room other than that in which an arrest occurs—or, for that matter, for searching through all the desk drawers or other closed or concealed areas in that room itself. Such searches, in the absence of well-recognized exceptions, may be made only under the authority of a search warrant.”³⁰

Although the viability of Chimel had been in doubt for some time as the Court refined and applied its analysis of reasonable and justifiable expectations of privacy,³¹ it has in some but not all contexts survived the changed rationale. Thus, in Mincey v. Arizona,³² the Court rejected a state effort to create a “homicide-scene” exception for a warrantless search of an entire apartment extending over four days. The occupant had been arrested and removed and it was true, the Court observed, that a person legally taken into custody has a lessened right of privacy in his person, but he does not have a lessened right of privacy in his entire house. And, in United States v. Chadwick,³³ emphasizing a person’s reasonable expectation of privacy in his luggage or other baggage, the Court held that, once police have arrested and immobilized a suspect, validly seized bags are not subject to search without a warrant.³⁴ Police may, however, in the course of jailing an arrested suspect, conduct an inventory search of the individual’s personal effects, including the contents of a shoulder bag, since “the scope of a station-house search may in some circumstances be even greater than those supporting a search immediately following arrest.”³⁵

Chimel has, however, been qualified by another consideration. Not only may officers search areas within the arrestee’s immediate control in order to alleviate any threat posed by the arrestee, but they may extend that search if there may be a threat posed by “unseen third parties in the house.” A “protective sweep” of the entire premises (including an arrestee’s home) may be undertaken on less than probable cause if officers have a “reasonable belief,” based on “articulable facts,” that the area to be swept may harbor an individual posing a danger to those on the arrest scene.³⁶

Stating that it was “in no way alter[ing] the fundamental principles established in the Chimel case,” the Court in New York v. Belton³⁷ held that police officers who had made a valid arrest of the occupant of a vehicle could make a contemporaneous search of the entire passenger compartment of the automobile, including containers found therein. Believing that a fairly simple rule understandable to authorities in the field was desirable, the Court ruled “that articles inside the relatively narrow compass of the passenger compartment of an automobile are in fact generally, if not inevitably, within ‘the area into which an arrestee might reach in order to grab a weapon or evidentiary ite[m].’”³⁸

Belton was “widely understood to allow a vehicle search incident to the arrest of a recent occupant even if there is no possibility the arrestee could gain access to the vehicle at the time of the search.”³⁹ In Arizona v. Gant,⁴⁰ however, the Court disavowed this understanding of Belton⁴¹ and held that “[p]olice may search a vehicle incident to a recent occupant’s arrest only if the arrestee is within reaching distance of the passenger compartment at the time of the search or it is reasonable to believe that the vehicle contains evidence of the offense of arrest.”⁴²

Amdt4.6.4.2 Vehicle Searches

In the early days of the automobile, the Court created an exception for searches of vehicles, holding in Carroll v. United States¹ that vehicles may be searched without warrants if the officer undertaking the search has probable cause to believe that the vehicle contains contraband. The Court explained that the mobility of vehicles would allow them to be quickly moved from the jurisdiction if time were taken to obtain a warrant.²

Initially, the Court limited Carroll’s reach, holding impermissible the warrantless seizure of a parked automobile merely because it is movable, and indicating that vehicles may be stopped only while moving or reasonably contemporaneously with movement.³ The Court also ruled that the search must be reasonably contemporaneous with the stop, so that it was not permissible to remove the vehicle to the station house for a warrantless search at the convenience of the police.⁴

The Court next developed a reduced privacy rationale to supplement the mobility rationale, explaining that “the configuration, use, and regulation of automobiles often may dilute the reasonable expectation of privacy that exists with respect to differently situated property.”⁵ “One has a lesser expectation of privacy in a motor vehicle because its function is transportation and it seldom serves as one’s residence or as the repository of personal effects. . . . It travels public thoroughfares where both its occupants and its contents are in plain view.’”⁶ Although motor homes serve as residences and as repositories for personal effects, and their contents are often shielded from public view, the Court extended the automobile exception to them as well, holding that there is a diminished expectation of privacy in a mobile home parked in a parking lot and licensed for vehicular travel, hence “readily mobile.”⁷

The Court has stated, however, that the automobile exception “does not permit an officer without a warrant to enter a home or its curtilage in order to search a vehicle therein.”⁸ This limit to the exception exists because “the scope of the automobile exception extends no further than the automobile itself.”⁹ To search a vehicle under the automobile exception, an officer “must have a lawful right of access” to that vehicle,¹⁰ and generally, law enforcement officers have no right to enter a home or its curtilage without express or implied permission or without a warrant.¹¹

The reduced expectancy concept has broadened police powers to conduct automobile searches without warrants, but they still must have probable cause to search a vehicle,¹² and they may not make random stops of vehicles on the roads but instead must base stops of individual vehicles on probable cause or some “articulable and reasonable suspicion”¹³ of traffic or safety violation or some other criminal activity.¹⁴ If police stop a vehicle, then the vehicle’s passengers as well as its driver are deemed to have been seized from the moment the car comes to a halt, and the passengers as well as the driver may challenge the constitutionality of the stop.¹⁵ A driver with lawful possession and control of a rental car may also be able to challenge the constitutionality of a stop, even if that driver is not listed as an authorized driver on the rental agreement.¹⁶ Likewise, a police officer may frisk (pat down for weapons) both the driver and any passengers whom he reasonably concludes “might be armed and presently dangerous.”¹⁷

By contrast, fixed-checkpoint stops in the absence of any individualized suspicion have been upheld for purposes of promoting highway safety¹⁸ or policing the international border,¹⁹ but not for more generalized law enforcement purposes.²⁰ Once police have validly stopped a vehicle, they may also, based on articulable facts warranting a reasonable belief that weapons may be present, conduct a Terry-type protective search of those portions of the passenger compartment in which a weapon could be placed or hidden.²¹ And, in the absence of such reasonable suspicion as to weapons, police may seize contraband and suspicious items “in plain view” inside the passenger compartment.²²

Although officers who have stopped a car to issue a routine traffic citation may conduct a Terry-type search, even including a pat-down of driver and passengers if there is reasonable suspicion that they are armed and dangerous, they may not conduct a full-blown search of the car²³ unless they exercise their discretion to arrest the driver instead of issuing a citation.²⁴ And once police have probable cause to believe there is contraband in a vehicle, they may remove the vehicle from the scene to the station house in order to conduct a search, without thereby being required to obtain a warrant.²⁵ “[T]he justification to conduct such a warrantless search does not vanish once the car has been immobilized; nor does it depend upon a reviewing court’s assessment of the likelihood in each particular case that the car would have been driven away, or that its contents would have been tampered with, during the period required for the police to obtain a warrant.”²⁶ Because of the lessened expectation of privacy, inventory searches of impounded automobiles are justifiable in order to protect public safety and the owner’s property, and any evidence of criminal activity discovered in the course of the inventories is admissible in court.²⁷ The Justices were evenly divided, however, on the propriety of warrantless seizure of an arrestee’s automobile from a public parking lot several hours after his arrest, its transportation to a police impoundment lot, and the taking of tire casts and exterior paint scrapings.²⁸

Police in undertaking a warrantless search of an automobile may not extend the search to the persons of the passengers therein²⁹ unless there is a reasonable suspicion that the passengers are armed and dangerous, in which case a Terry pat down is permissible,³⁰ or unless there is individualized suspicion of criminal activity by the passengers.³¹ But because passengers in an automobile have no reasonable expectation of privacy in the interior area of the car, a warrantless search of the glove compartment and the spaces under the seats, which turned up evidence implicating the passengers, invaded no Fourth Amendment interest of the passengers.³² Luggage and other closed containers found in automobiles may also be subjected to warrantless searches based on probable cause, regardless of whether the luggage or containers belong to the driver or to a passenger, and regardless of whether it is the driver or a passenger who is under suspicion.³³ The same rule now applies whether the police have probable cause to search only the containers³⁴ or whether they have probable cause to search the automobile for something capable of being held in the container.³⁵

Amdt4.6.4.3 Containers in Vehicles

Not only is the warrant requirement inapplicable to brief stops of vessels, but also none of the safeguards applicable to stops of automobiles on less than probable cause are necessary predicates to stops of vessels. In United States v. Villamonte-Marquez,¹ the Court upheld a random stop and boarding of a vessel by customs agents, lacking any suspicion of wrongdoing, for purpose of inspecting documentation. The boarding was authorized by statute derived from an act of the First Congress² and hence had “an impressive historical pedigree” carrying with it a presumption of constitutionality. Moreover, “important factual differences between vessels located in waters offering ready access to the open sea and automobiles on principal thoroughfares in the border area” justify application of a less restrictive rule for vessel searches. The reason why random stops of vehicles have been held impermissible under the Fourth Amendment, the Court explained, is that stops at fixed checkpoints or roadblocks are both feasible and less subject to abuse of discretion by authorities. “But no reasonable claim can be made that permanent checkpoints would be practical on waters such as these where vessels can move in any direction at any time and need not follow established ‘avenues’ as automobiles must do.”³ Because there is a “substantial” governmental interest in enforcing documentation laws, “especially in waters where the need to deter or apprehend smugglers is great,” the Court found the “limited” but not “minimal” intrusion occasioned by boarding for documentation inspection to be reasonable.⁴ Dissenting Justice William Brennan argued that the Court for the first time was approving “a completely random seizure and detention of persons and an entry onto private, noncommercial premises by police officers, without any limitations whatever on the officers’ discretion or any safeguards against abuse.”⁵

Amdt4.6.4.4 Plain View Doctrine

Somewhat similar in rationale is the rule that objects falling in the “plain view” of an officer who has a right to be in the position to have that view are subject to seizure without a warrant¹ or that, if the officer needs a warrant or probable cause to search and seize, his lawful observation will provide grounds therefor.² The plain view doctrine is limited, however, by the probable cause requirement: officers must have probable cause to believe that items in plain view are contraband before they may search or seize them.³

The Court has analogized from the plain view doctrine to hold that, once officers have lawfully observed contraband, “the owner’s privacy interest in that item is lost,” and officers may reseal a container, trace its path through a controlled delivery, and seize and reopen the container without a warrant.⁴

Amdt4.6.5.1 Terry Stop and Frisks Doctrine and Practice

While arrests are subject to Fourth Amendment requirements, courts have followed the common law in upholding the authority of police officers to take a person into custody without a warrant if they have probable cause to believe the person has committed a felony or a misdemeanor in their presence.¹ Probable cause must be satisfied by conditions existing prior to the arrest and cannot be established retroactively.² There are, however, instances when a person’s conduct or manner arouse a police officer’s suspicions, but probable cause to arrest such a person is lacking.³ In its 1968 Terry v. Ohio decision,⁴ the Court, with only Justice William O. Douglas dissenting, approved a police officer’s on-the-street investigation that involved “patting down” the subject of the investigation for weapons.

Terry arose when a police officer observed three individuals engaging in conduct that appeared to him, on the basis of training and experience, to be “casing” a store for a likely armed robbery. Upon approaching the men, identifying himself, and not receiving prompt identification, the officer seized one of the men, patted the exterior of his clothes, and discovered a gun. For the Court, Chief Justice Earl Warren wrote that the Fourth Amendment applies “whenever a police officer accosts an individual and restrains his freedom to walk away.”⁵ Because the warrant clause is necessarily and practically of no application to the type of on-the-street encounter present in Terry, the Chief Justice considered whether the policeman’s actions were reasonable. The Chief Justice reasoned that the test of reasonableness in this sort of situation is whether the police officer can point to “specific and articulable facts which, taken together with rational inferences from those facts” would lead a neutral magistrate on review to conclude that a man of reasonable caution would be warranted in believing that possible criminal behavior was at hand and that both an investigative stop and a “frisk” was required.⁶ Because the police officer witnessed conduct that reasonably led him to believe that an armed robbery was in prospect, he was as reasonably led to believe that the men were armed and probably dangerous and that his safety required a “frisk.” Because the object of a “frisk” is to discover dangerous weapons, “it must therefore be confined in scope to an intrusion reasonably designed to discover guns, knives, clubs, or other hidden instruments for the assault of the police officer.”⁷

In a later case, the Court held that an officer may seize an object if, in the course of a weapons frisk, “plain touch” reveals the presence of the object, and the officer has probable cause to believe it is contraband.⁸ The Court viewed the situation as analogous to that covered by the “plain view” doctrine: obvious contraband may be seized, but a search may not be expanded to determine whether an object is contraband.⁹ Also impermissible is physical manipulation, without reasonable suspicion, of a bus passenger’s carry-on luggage stored in an overhead compartment.¹⁰

Terry did not address the grounds that could permissibly lead an officer to stop a person on the street or elsewhere in order to ask questions rather than frisk for weapons, the right of the stopped individual to refuse to cooperate, and the permissible response of the police to that refusal. The Court provided a partial answer in its 2004 decision, Hiibel v. Sixth Judical District Court, when it upheld a state law that required a suspect to disclose his name in the course of a valid Terry stop.¹¹ Questions about a suspect’s identity “are a routine and accepted part of many Terry stops,” the Court explained.¹²

After Terry, the standard for stops for investigative purposes evolved into one of “reasonable suspicion of criminal activity.” That test permits some stops and questioning without probable cause in order to allow police officers to explore the foundations of their suspicions.¹³ Although it did not elaborate a set of rules to govern applying the tests, the Court was initially restrictive in recognizing permissible bases for reasonable suspicion.¹⁴ The Court invalidated extensive intrusions on individual privacy, for example, transporting a person to the station house for interrogation and fingerprinting, absent probable cause,¹⁵ and the Court has held that an uncorroborated, anonymous tip is an insufficient basis for a Terry stop and that there is no “firearms” exception to the reasonable suspicion requirement.¹⁶ Since the 1980s, however, the Court has taken less restrictive approaches.¹⁷

The Court’s approach for when a “seizure” has occurred for Fourth Amendment purposes has evolved. The Terry Court recognized in dictum that “not all personal intercourse between policemen and citizens involves ‘seizures’ of persons,” and suggested that “[o]nly when the officer, by means of physical force or show of authority, has in some way restrained the liberty of a citizen may we conclude that a ‘seizure’ has occurred.”¹⁸ In the 1980 United States v. Mendenhall decision, Justice Potter Stewart, joined by Justice William Rehnquist, proposed a similar standard—that a person has been seized “only if, in view of all of the circumstances surrounding the incident, a reasonable person would have believed that he was not free to leave.”¹⁹ A majority of the Justices subsequently endorsed this reasonable perception standard²⁰ and applied it in several later cases in which the admissibility of evidence turned on whether police actions prior to uncovering evidence violated the Fourth Amendment. No seizure occurred, for example, when Immigration and Naturalization Service (INS) agents seeking to identify unlawfully present aliens conducted workforce surveys within a garment factory; while some agents were positioned at exits, others systematically moved through the factory and questioned employees.²¹ The Court held this brief questioning, even with blocked exits, amounted to “classic consensual encounters rather than Fourth Amendment seizures.”²² The Court has also ruled that no seizure occurred when police in a squad car drove alongside a suspect who had turned and run down the sidewalk when he saw the squad car approach. Under the circumstances (no siren, flashing lights, display of a weapon, or blocking of the suspect’s path), the Court concluded the police conduct “would not have communicated to the reasonable person an attempt to capture or otherwise intrude upon [one’s] freedom of movement.”²³

The Court later ruled that the Mendenhall “free-to-leave” inquiry was misplaced in the context of a police sweep of a bus, but that a modified reasonable perception approach still governed.²⁴ In conducting a bus sweep aimed at detecting illegal drugs and their couriers, police officers typically board a bus during a stopover at a terminal and ask to inspect tickets, identification, and at times, the luggage of selected passengers. The Court did not focus on whether an “arrest” had taken place, but instead suggested that the appropriate inquiry is “whether a reasonable person would feel free to decline the officers’ requests or otherwise terminate the encounter.”²⁵ “When the person is seated on a bus and has no desire to leave,” the Court explained, “the degree to which a reasonable person would feel that he or she could leave is not an accurate measure of the coercive effect of the encounter.”²⁶

The Supreme Court’s analysis of seizure, however, is different in the context of fleeing suspects, where the Court seemingly applies a more formalistic approach than the Mendenhall reasonable-perception standard. In Brower v. County of Inyo, the Supreme Court concluded that a seizure occurred when a suspect’s car collided with a police roadblock, and explained that a “[v]iolation of the Fourth Amendment requires an intentional acquisition of physical control.”²⁷ The Court reasoned that such a use of force becomes a seizure “only when there is a governmental termination of freedom of movement through means intentionally applied.”²⁸ The Court seemingly modified that standard in California v. Hodari D., another Fourth Amendment case involving a fleeing suspect.²⁹ In Hodari D., the Court held that an actual chase with evident intent to capture did not amount to a “seizure” because the suspect had not complied with the officer’s order to halt. The Court reasoned that Mendenhall stated a “necessary” but not a “sufficient” condition for a seizure of the person is through a show of authority.³⁰ A Fourth Amendment “seizure” of the person, the Court determined, is the same as a common law arrest; there must be either application of physical force (or the laying on of hands) or submission to the assertion of authority.³¹ Three decades after Hodari D., the Court revisited the nature of seizure in the context of a fleeing suspect in its 2021 Torres v. Madrid decision.³² In Torres, the Court held that a suspect was seized when struck twice by bullets fired by law enforcement, even though she temporarily evaded capture.³³ The Court reasoned that the “application of physical force to the body of a person with intent to restrain is a seizure” within the meaning of the Fourth Amendment, “even if the force does not succeed in subduing the person.”³⁴ According to the Court, such a seizure lasts “only as long as the application of force.”³⁵ Thus, in Torres, officers seized the suspect “the instant that the bullets struck her.”³⁶ The Court clarified that, unlike seizure by application of force, seizure by show of authority still requires either “voluntary submission” or “termination of freedom of movement.”³⁷

Amdt4.6.5.2 Terry Stop and Frisks and Vehicles

A Terry search need not be limited to a stop and frisk of the person, but may extend as well to a protective search of the passenger compartment of a car if an officer possesses “a reasonable belief, based on specific and articulable facts . . . that the suspect is dangerous and . . . may gain immediate control of weapons.”¹ How lengthy a Terry detention may be varies with the circumstances. In approving a twenty-minute detention of a driver made necessary by the driver’s own evasion of drug agents and a state police decision to hold the driver until the agents could arrive on the scene, the Court indicated that it is “appropriate to examine whether the police diligently pursued a means of investigation that was likely to confirm or dispel their suspicions quickly, during which time it was necessary to detain the defendant.”²

Similar principles govern detention of luggage at airports in order to detect the presence of drugs; Terry “limitations applicable to investigative detentions of the person should define the permissible scope of an investigative detention of the person’s luggage on less than probable cause.”³ The general rule is that “when an officer’s observations lead him reasonably to believe that a traveler is carrying luggage that contains narcotics, the principles of Terry . . . would permit the officer to detain the luggage briefly to investigate the circumstances that aroused his suspicion, provided that the investigative detention is properly limited in scope.”⁴ Seizure of luggage for an expeditious “canine sniff” by a dog trained to detect narcotics can satisfy this test even though seizure of luggage is in effect detention of the traveler, since the procedure results in “limited disclosure,” impinges only slightly on a traveler’s privacy interest in the contents of personal luggage, and does not constitute a search within the meaning of the Fourth Amendment.⁵ By contrast, taking a suspect to an interrogation room on grounds short of probable cause, retaining his air ticket, and retrieving his luggage without his permission taints consent given under such circumstances to open the luggage, since by then the detention had exceeded the bounds of a permissible Terry investigative stop and amounted to an invalid arrest.⁶ But the same requirements for brevity of detention and limited scope of investigation are apparently inapplicable to border searches of international travelers, the Court having approved a twenty-four hour detention of a traveler suspected of smuggling drugs in her alimentary canal.⁷

Amdt4.6.6.1 Overview of Border Searches

Congress has broad authority to regulate persons or items entering the United States, an authority rooted in its power to regulate foreign commerce and to protect the integrity of the Nation’s borders.¹ Authorized by the First Congress,² customs searches at the border require no warrant, probable cause, or even a showing of some degree of suspicion that accompanies investigatory stops.³ The Supreme Court has described searches at the international border as “necessary to prevent smuggling and to prevent prohibited articles from entry.”⁴ Despite this seemingly broad authority to search persons and items at the border, the Fourth Amendment provides some constraints. The Fourth Amendment generally requires a government officer to secure a warrant based on probable cause before conducting a search or seizure.⁵ Nonetheless, because the “touchstone” of the Fourth Amendment is reasonableness,⁶ courts have recognized certain exceptions when the government may engage in a warrantless search or seizure.⁷

Amdt4.6.6.2 Searches at International Borders

Under what is typically referred to as the “border search exception” to the Fourth Amendment, federal officers may generally conduct warrantless searches of persons and items upon their entry into the United States without needing reasonable suspicion or probable cause of wrongdoing.¹ The Supreme Court has stated, “[t]hat searches made at the border, pursuant to the longstanding right of the sovereign to protect itself by stopping and examining persons and property crossing into this country, are reasonable simply by virtue of the fact that they occur at the border, should, by now, require no extended demonstration.”² The Court has cited a lower expectation of privacy at the border, articulating that “the Fourth Amendment balance between the interests of the Government and the privacy right of the individual is also struck much more favorably to the Government at the border.”³ While searches subject to this reduced Fourth Amendment scrutiny may potentially take place along any segment of the international border, stops and searches may also occur at the “functional equivalent” of the border, including international airports in the United States and post offices receiving international airmail.⁴

When determining whether a border search or detention is reasonable, courts have generally distinguished between routine and nonroutine searches and seizures—with the latter requiring a level of particularized suspicion of illegal activity. The Supreme Court has described a nonroutine search or seizure as one that goes beyond a limited intrusion, such as prolonged detentions, strip searches, body cavity searches, and involuntary x-ray searches.⁵

In United States v. Montoya de Hernandez, the Supreme Court ruled that a sixteen hour detention of an arriving airline traveler from Colombia did not violate the Fourth Amendment—even though it went beyond the scope of a routine customs inspection—because it was based on reasonable suspicion that she was smuggling contraband.⁶ Additionally, according to the Court, an extended detention as a result of a border search may be constitutionally permissible if the detention “was reasonably related in scope to the circumstances which justified it initially.”⁷

In United States v. Flores-Montano, the Supreme Court held that federal officers may search motor vehicles at the border without a warrant, reasonable suspicion, or probable cause, even to the extent of removing, disassembling, and reassembling the fuel tank.⁸ The Court observed, however, that there may be circumstances in which a search of a vehicle at the international border would “be deemed unreasonable because of the particularly offensive manner in which it is carried out.”⁹

Amdt4.6.6.3 Searches Beyond the Border

Under the “border search exception,” federal officers may generally conduct routine, warrantless searches of persons and items entering the United States without reasonable suspicion or probable cause of unlawful activity. However, stops and searches conducted in areas farther from the border may require at least heightened suspicion or probable cause of unlawful activity to withstand Fourth Amendment scrutiny.

The Supreme Court has addressed Fourth Amendment limitations on “roving patrols” near the border.¹ In Almeida-Sanchez v. United States, the Court held that a warrantless stop and search of an automobile some twenty miles from the border violated the Fourth Amendment because the Border Patrol officers lacked probable cause to believe that the vehicle contained unlawfully present aliens.² While recognizing the government’s authority to conduct routine inspections and searches at the border without a warrant or any individualized suspicion, the Court determined that vehicle searches in areas away from the physical border were “of a wholly different sort” because individuals have greater Fourth Amendment protections in the interior of the United States.³

In United States v. Brignoni-Ponce, the Supreme Court considered whether roving patrol stops for the more limited purpose of questioning motorists about immigration status or any suspicious circumstance is constitutionally permissible.⁴ The Court held that roving patrol stops must be supported by “specific articulable facts, together with rational inferences from those facts, that reasonably warrant suspicion” that an automobile contains unlawfully present aliens.⁵ The Court reasoned that stops absent suspicion would risk “potentially unlimited interference” with border area residents’ use of the highways, and determined that the “reasonable suspicion” standard should apply to roving patrol stops given their “modest intrusion.”⁶ The Court held that federal officers who stopped a vehicle near the border lacked reasonable suspicion because they relied solely on the apparent Mexican ancestry of the vehicle’s occupants, and that the occupants’ ancestry in itself failed to provide reasonable belief that the vehicle concealed unlawfully present aliens.⁷

Applying Brignoni-Ponce’s reasonable suspicion test, the Supreme Court held in United States v. Cortez that there was reasonable suspicion for a stop near the border because the agents had previously uncovered clues of alien smuggling in the area and knew where the suspects would likely appear.⁸ In United States v. Arvizu, the Court concluded that a Border Patrol agent had reasonable suspicion to stop a minivan found to be carrying more than 100 pounds of contraband based on observing the van on a remote road often used by smugglers and other observations of the van’s occupants.⁹ “Taken together,” these observations raised a reasonable inference of criminal activity.¹⁰

The Supreme Court has also addressed vehicle stops at fixed immigration checkpoints, which, unlike roving patrols, are typically located at stationary points on major highways near the border. In United States v. Martinez-Fuerte, the Supreme Court held that federal officers may briefly stop and question motorists at “reasonably located” checkpoints, even in the absence of reasonable suspicion that a vehicle contains unlawfully present aliens.¹¹ Given the “regularized manner” of immigration checkpoints, the Court reasoned, motorists “are not taken by any surprise” when they see a checkpoint and can be reasonably certain that the stops are authorized.¹²

However, there are Fourth Amendment constraints on Border Patrol agents’ ability to engage in more intrusive actions at fixed immigration checkpoints.¹³ In United States v. Ortiz, the Supreme Court held that “at traffic checkpoints removed from the border and its functional equivalents, officers may not search private vehicles without consent or probable cause” of unlawful activity.¹⁴ The Court reasoned that the routine nature of a checkpoint stop “does not mitigate the invasion of privacy that a search entails” and that allowing agents to have unlimited discretion to search a vehicle at a checkpoint would be antithetical to the Fourth Amendment.¹⁵ Thus, in that case, the Court held that Border Patrol agents unlawfully searched a vehicle at a checkpoint because they lacked probable cause that the vehicle contained unlawfully present aliens.¹⁶

The Supreme Court has also considered the constitutionality of warrantless stops and inspections of vessels within interior U.S. waters away from the border.¹⁷ In United States v. Villamonte-Marquez, the Court held that government officers may board vessels on inland waters with ready access to the open sea for routine document checks without suspicion of criminal activity.¹⁸ The Court reasoned that the government has a strong interest in assuring compliance with vessel documentation requirements, especially in heavy drug trafficking areas, and that the nature of maritime commerce made it impracticable to stop all vessels at permanent water checkpoints.¹⁹

Amdt4.6.6.4 Drug Testing

In two 1989 decisions the Court held that no warrant, probable cause, or even individualized suspicion is required for mandatory drug testing of certain classes of railroad and public employees. In each case, “special needs beyond the normal need for law enforcement” were identified as justifying the drug testing. In Skinner v. Railway Labor Executives’ Ass’n,¹ the Court upheld regulations requiring railroads to administer blood, urine, and breath tests to employees involved in certain train accidents or violating certain safety rules; in National Treasury Employees Union v. Von Raab² the Court upheld a Customs Service screening program requiring urine testing of employees seeking transfer or promotion to positions having direct involvement with drug interdiction or to positions requiring the incumbent to carry firearms.

The Court in Skinner found a “compelling” governmental interest in testing the railroad employees without any showing of individualized suspicion, since operation of trains by anyone impaired by drugs “can cause great human loss before any signs of impairment become noticeable.”³ By contrast, the intrusions on privacy were termed “limited.” Blood and breath tests were passed off as routine; the urine test, although more intrusive, was deemed permissible because of the “diminished expectation of privacy” in employees having some responsibility for safety in a pervasively regulated industry.⁴ The lower court’s emphasis on the limited effectiveness of the urine test (it detects past drug use but not necessarily the level of impairment) was misplaced, the Court ruled. It is enough that the test may provide some useful information for an accident investigation; in addition, the test may promote deterrence as well as detection of drug use.⁵

In Von Raab the governmental interests underlying the Customs Service’s screening program were also termed “compelling”: to ensure that persons entrusted with a firearm and the possible use of deadly force not suffer from drug-induced impairment of perception and judgment, and that “front-line [drug] interdiction personnel [be] physically fit, and have unimpeachable integrity and judgment.”⁶ The possibly “substantial” interference with privacy interests of these Customs employees was justified, the Court concluded, because, “[u]nlike most private citizens or government employees generally, they have a diminished expectation of privacy.”⁷

Emphasizing the “special needs” of the public school context, reflected in the “custodial and tutelary” power that schools exercise over students, and also noting schoolchildren’s diminished expectation of privacy, the Court in Vernonia School District v. Acton⁸ upheld a school district’s policy authorizing random urinalysis drug testing of students who participate in interscholastic athletics. The Court redefined the term “compelling” governmental interest. The phrase does not describe a “fixed, minimum quantum of governmental concern,” the Court explained, but rather “describes an interest which appears important enough to justify the particular search at hand.”⁹ Applying this standard, the Court concluded that “deterring drug use by our Nation’s schoolchildren is at least as important as enhancing efficient enforcement of the Nation’s laws against the importation of drugs . . . or deterring drug use by engineers and trainmen.”¹⁰ On the other hand, the interference with privacy interests was not great, the Court decided, since schoolchildren are routinely required to submit to various physical examinations and vaccinations. Moreover, “[l]egitimate privacy expectations are even less [for] student athletes, since they normally suit up, shower, and dress in locker rooms that afford no privacy, and since they voluntarily subject themselves to physical exams and other regulations above and beyond those imposed on non-athletes.”¹¹ The Court “caution[ed] against the assumption that suspicionless drug testing will readily pass muster in other contexts,” identifying as “the most significant element” in Vernonia the fact that the policy was implemented under the government’s responsibilities as guardian and tutor of schoolchildren.¹²

Seven years later, the Court in Board of Education v. Earls¹³ extended Vernonia to uphold a school system’s drug testing of all junior high and high school students who participated in extra-curricular activities. The lowered expectation of privacy that athletes have “was not essential” to the decision in Vernonia, Justice Clarence Thomas wrote for a 5-4 Court majority.¹⁴ Rather, that decision “depended primarily upon the school’s custodial responsibility and authority.”¹⁵ Another distinction was that, although there was some evidence of drug use among the district’s students, there was no evidence of a significant problem, as there had been in Vernonia. Rather, the Court referred to “the nationwide epidemic of drug use,” and stated that there is no “threshold level” of drug use that need be present.¹⁶ Because the students subjected to testing in Earls had the choice of not participating in extra-curricular activities rather than submitting to drug testing, the case stops short of holding that public school authorities may test all junior and senior high school students for drugs. Thus, although the Court’s rationale seems broad enough to permit across-the-board testing,¹⁷ Justice Stephen Breyer’s concurrence, emphasizing among other points that “the testing program avoids subjecting the entire school to testing,”¹⁸ raises some doubt on this score. The Court also left another basis for limiting the ruling’s sweep by asserting that “regulation of extracurricular activities further diminishes the expectation of privacy among schoolchildren.”¹⁹

In two other cases, the Court found that there were no “special needs” justifying random testing. Georgia’s requirement that candidates for state office certify that they had passed a drug test, the Court ruled in Chandler v. Miller²⁰ was “symbolic” rather than “special.” There was nothing in the record to indicate any actual fear or suspicion of drug use by state officials, the required certification was not well designed to detect illegal drug use, and candidates for state office, unlike the customs officers held subject to drug testing in Von Raab, are subject to “relentless” public scrutiny. In the second case, a city-run hospital’s program for drug screening of pregnant patients suspected of cocaine use was invalidated because its purpose was to collect evidence for law enforcement.²¹ In the previous three cases in which random testing had been upheld, the Court pointed out, the “special needs” asserted as justification were “divorced from the general interest in law enforcement.”²² By contrast, the screening program’s focus on law enforcement brought it squarely within the Fourth Amendment’s restrictions.

Amdt4.6.6.5 National Security

In Katz v. United States,¹ Justice Byron White sought to preserve for a future case the possibility that in “national security cases” electronic surveillance upon the authorization of the President or the Attorney General could be permissible without prior judicial approval.² The Executive Branch then asserted the power to wiretap and to “bug” in two types of national security situations, against domestic subversion and against foreign intelligence operations, first basing its authority on a theory of “inherent” presidential power and then in the Supreme Court withdrawing to the argument that such surveillance was a “reasonable” search and seizure and therefore valid under the Fourth Amendment. Unanimously, the Court held that at least in cases of domestic subversive investigations, compliance with the warrant provisions of the Fourth Amendment was required.³ Whether or not a search was reasonable, wrote Justice Lewis Powell for the Court, was a question which derived much of its answer from the warrant clause; except in a few narrowly circumscribed classes of situations, only those searches conducted pursuant to warrants were reasonable. The Government’s duty to preserve the national security did not override the guarantee that before government could invade the privacy of its citizens it must present to a neutral magistrate evidence sufficient to support issuance of a warrant authorizing that invasion of privacy.⁴ This protection was even more needed in “national security cases” than in cases of “ordinary” crime, the Justice continued, because the tendency of government so often is to regard opponents of its policies as a threat and hence to tread in areas protected by the First Amendment as well as by the Fourth.⁵ Rejected also was the argument that courts could not appreciate the intricacies of investigations in the area of national security or preserve the secrecy which is required.⁶

The question of the scope of the President’s constitutional powers, if any, remains judicially unsettled.⁷ Congress has acted, however, providing for a special court to hear requests for warrants for electronic surveillance in foreign intelligence situations, and permitting the President to authorize warrantless surveillance to acquire foreign intelligence information provided that the communications to be monitored are exclusively between or among foreign powers and there is no substantial likelihood any “United States person” will be overheard.⁸

Amdt4.6.6.6 School Searches

In New Jersey v. T.L.O.,¹ the Court set forth the principles governing searches by public school authorities. The Fourth Amendment applies to searches conducted by public school officials because “school officials act as representatives of the State, not merely as surrogates for the parents.”² However, “the school setting requires some easing of the restrictions to which searches by public authorities are ordinarily subject.”³ Neither the warrant requirement nor the probable cause standard is appropriate, the Court ruled. Instead, a simple reasonableness standard governs all searches of students’ persons and effects by school authorities.⁴ A search must be reasonable at its inception, that is, there must be “reasonable grounds for suspecting that the search will turn up evidence that the student has violated or is violating either the law or the rules of the school.”⁵ School searches must also be reasonably related in scope to the circumstances justifying the interference, and “not excessively intrusive in light of the age and sex of the student and the nature of the infraction.”⁶ In applying these rules, the Court upheld as reasonable the search of a student’s purse to determine whether the student, accused of violating a school rule by smoking in the lavatory, possessed cigarettes. The search for cigarettes uncovered evidence of drug activity held admissible in a prosecution under the juvenile laws.

In Safford Unified School District #1 v. Redding,⁷ a student found in possession of prescription ibuprofen pills at school stated that the pills had come from another student, 13-year-old Savana Redding. The Court found that the first student’s statement was sufficiently plausible to warrant suspicion that Savana was involved in pill distribution, and that this suspicion was enough to justify a search of Savana’s backpack and outer clothing.⁸ School officials, however, had also “directed Savana to remove her clothes down to her underwear, and then ‘pull out’ her bra and the elastic band on her underpants”⁹—an action that the Court thought could fairly be labeled a strip search. Taking into account that “adolescent vulnerability intensifies the patent intrusiveness of the exposure” and that, according to a study, a strip search can “result in serious emotional damage,” the Court found that the search violated the Fourth Amendment.¹⁰ “Because there were no reasons to suspect the drugs presented a danger or were concealed in her underwear,” the Court wrote, “the content of the suspicion failed to match the degree of intrusion.”¹¹ But, even though the Court found that the search had violated the Fourth Amendment, it found that the school officials who conducted the search were protected from liability through qualified immunity, because the law prior to Redding was not clearly established.¹²

Amdt4.6.6.7 Searches of Prisoners, Parolees, and Probationers

The “undoubted security imperatives involved in jail supervision” require “defer[ence] to the judgment of correctional officials unless the record contains substantial evidence showing their policies are an unnecessary or unjustified response to the problems of jail security.”¹ So saying, the Court, in Florence v. Board of Chosen Freeholders, upheld routine strip searches, including close-up visual cavity inspections, as part of processing new arrestees for entry into the general inmate population, without the need for individualized suspicion and without an exception for those arrested for minor offenses.² Correctional officials had asserted significant penological interests to justify routine strip searches of new arrivals: detecting and preventing the introduction into the inmate population of infections, infestations, and contraband of all sorts; and identifying gang members. Having cited serious concerns and having applied their professional expertise, the officials had, in the Court’s opinion, acted reasonably and not clearly overreacted. But despite taking a deferential approach and recounting the grave dangers correctional officers face, the Florence Court did not hold that individuals being processed for detention have no privacy rights at all. In separate concurrences, moreover, two members of the five-Justice majority held out the prospect of exceptions and refinements in future rulings on blanket strip search policies for new detainees.³

The Court in Maryland v. King cited a legitimate interest in having safe and accurate booking procedures to identify persons being taken into custody in order to sustain taking DNA samples from those charged with serious crimes.⁴ Tapping the “unmatched potential of DNA identification” facilitates knowing with certainty who the arrestee is, the arrestee’s criminal history, the danger the arrestee poses to others, the arrestee’s flight risk, and other relevant facts.⁵ By comparison, the Court characterized an arrestee’s expectation of privacy as diminished and the intrusion posed by a cheek swab as minimal.⁶

Searches of prison cells by prison administrators are not limited even by a reasonableness standard, the Court’s having held that “the Fourth Amendment proscription against unreasonable searches does not apply within the confines of the prison cell.”⁷ Thus, prison administrators may conduct random “shakedown” searches of inmates’ cells without the need to adopt any established practice or plan, and inmates must look to the Eighth Amendment or to state tort law for redress against harassment, malicious property destruction, and the like.

Neither a warrant nor probable cause is needed for an administrative search of a probationer’s home. It is enough, the Court ruled in Griffin v. Wisconsin, that such a search was conducted pursuant to a valid regulation that itself satisfies the Fourth Amendment’s reasonableness standard (for example, by requiring “reasonable grounds” for a search).⁸ “A State’s operation of a probation system, like its operation of a school, government office or prison, or its supervision of a regulated industry, . . . presents ‘special needs’ beyond normal law enforcement that may justify departures from the usual warrant and probable cause requirements.”⁹ “Probation, like incarceration, is a form of criminal sanction,” the Court noted, and a warrant or probable cause requirement would interfere with the “ongoing [non-adversarial] supervisory relationship” required for proper functioning of the system.¹⁰ A warrant is also not required if the purpose of a search of a probationer is investigate a crime rather than to supervise probation.¹¹

“[O]n the ‘continuum’ of state-imposed punishments . . . , parolees have [even] fewer expectations of privacy than probationers, because parole is more akin to imprisonment than probation is to imprisonment.”¹² The Fourth Amendment, therefore, is not violated by a warrantless search of a parolee that is predicated upon a parole condition to which a prisoner agreed to observe during the balance of his sentence.¹³

Amdt4.6.6.8 Workplace Searches

Similar principles apply to a public employer’s work-related search of its employees’ offices, desks, or file cabinets, except that in this context the Court distinguished searches conducted for law enforcement purposes. In O’Connor v. Ortega,¹ a majority of Justices agreed, albeit on somewhat differing rationales, that neither a warrant nor a probable cause requirement should apply to employer searches “for noninvestigatory, work-related purposes, as well as for investigations of work-related misconduct.”² Four Justices would require a case-by-case inquiry into the reasonableness of such searches;³ one would hold that such searches “do not violate the Fourth Amendment.”⁴

In City of Ontario v. Quon,⁵ the Court bypassed adopting an approach for determining a government employee’s reasonable expectation of privacy, an issue unresolved in O’Connor. Rather, the Quon Court followed the “special needs” holding in O’Connor and found that, even assuming a reasonable expectation of privacy, a city’s warrantless search of the transcripts of a police officer’s on-duty text messages on city equipment was reasonable because it was justified at its inception by noninvestigatory work-related purposes and was not excessively intrusive.⁶ A jury had found the purpose of the search to be to determine whether the city’s contract with its wireless service provider was adequate, and the Court held that “reviewing the transcripts was reasonable because it was an efficient and expedient way to determine whether [the officer’s] overages were the result of work-related messaging or personal use.”⁷