Stop and Frisk

2012-09-12 09:43:23

In the Constitution, the provision limiting the power of police to search and arrest persons is the Fourth Amendment. Basically, the Fourth Amendment prohibits police conduct that is ‘‘unreasonable.’’ However, the Fourth Amendment, by its terms, applies only to ‘‘searches’’ and ‘‘seizures.’’ If police engage in an activity that does not rise to the level of a ‘‘search’’ or ‘‘seizure,’’ the Fourth Amendment does not apply, and police are free (at least from Fourth Amendment strictures) to pursue that activity. The question arises, does the term search include only full-blown, complete searches of a person, or does it also cover situations where police just do a frisk to check for weapons?

A counterpart to this question arises for seizures. Clearly seizure of a person occurs when police make a formal custodial arrest, but is it also a seizure when police just stop a person in public and detain the person for several minutes for questioning? The legitimacy of police using a ‘‘stop and frisk’’ technique was the issue for the Supreme Court in 1968 in Terry v. Ohio.

In the Terry decision, the Supreme Court established a new category of police activity for intrusions that were less than a full search or arrest but still were covered by the Fourth Amendment. Because the intrusion was less, the activities were authorized by a lower level of grounds than the usual probable cause required for a full search or arrest. The new categories recognized in Terry became a significant exception to traditional Fourth Amendment doctrine, which required probable cause before police could act. The Supreme Court used a balancing analysis to establish these new types of activity and to set the grounds to justify them, balancing the government’s need to search or seize against the invasion to the individual. Overall, setting up these new categories has been useful to give police more flexibility in dealing with rapidly unfolding confrontations on the street.

In Terry, the Court held that police might do a limited seizure of a person if it is justified by reasonable suspicion to believe criminal activity is afoot. Similarly, police may do a limited search of a person (a frisk or pat-down) if it is justified by reason to believe the defendant is armed and dangerous. These more limited intrusions required less ground to justify them. This decision, which created these new categories of police activity, can be usefully represented by the following diagram.

Continuum of Intrusiveness of Police Conduct

Since Terry was decided in 1968, the courts have been fleshing out the contours of stop-and-frisk law.


A stop is an encounter between police and a person that does not amount to an arrest but is intrusive enough to qualify as a seizure and so be subject to Fourth Amendment requirements. Courts have defined stops as beginning when police approach a person and the interaction is such that a reasonable person would not feel free to leave. A stop generally requires some physical force or show of authority by police. For example, a stop can be said to occur if police ‘‘blue-light’’ a car or use their sirens; flash their badges; brandish weapons; or grab a person’s arm and hold on. A variation of this reasonable-person-would-feel-free-to-leave test applies if the police confront a person in a confined area like the passenger seating of a bus or an airplane. Because a seated passenger cannot be said to feel free to leave, the test is whether a reasonable person would feel free to decline the officer’s requests or otherwise terminate the encounter. So if a person is seated on a bus and the police enter the bus and ask for permission to search the person’s luggage, the encounter qualifies as a stop only if a reasonable person would not feel free to decline the officer’s request.

Assuming the police encounter with a person rises to the level of a stop, police must justify the activity, that is, they must have adequate grounds or reasons for the stop. The grounds required for a stop have been defined by the Supreme Court as an articulable suspicion that criminal activity is afoot; more recently the Court refers to this standard as ‘‘reasonable suspicion.’’ Cases indicate that this level of suspicion is ‘‘considerably less’’ than 50 percent certainty and is also less than the standard of probable cause, which is required for an arrest. The Court has declined to set any more specific contours for the level of certainty required by ‘‘reasonable suspicion.’’

To determine whether reasonable suspicion exists, courts have indicated police should look to all the circumstances. The fact that some factors are innocent in themselves does not mean that those factors must be excluded. So, for example, if a couple flies from Chicago to Florida and turns right around and drives home the next day, this factor can be used as supporting reasonable suspicion that crime is occurring; it need not be excluded from the analysis because it is innocent on its face. Courts have often said that the question of whether reasonable suspicion exists is a common sense judgment not dependent on technicalities or formalities. Law enforcement officers are entitled to use their expertise in calculating whether reasonable suspicion exists. For example, if police find a brick-shaped package wrapped in cellophane and duct tape, based on their street experience police may conclude that the package contains illegal drugs. In Illinois v. Wardlow, the Supreme Court held that officers had reasonable suspicion where they were in a high-crime neighborhood and a person took off in unprovoked flight after seeing them. One controversial line of cases established what grounds were adequate for the police to stop persons in airports based on suspicion they were drug couriers. The Court held that police established reasonable suspicion to allow them to stop the defendant by showing that (1) the defendant paid $2,100 for two airplane tickets from a roll of $20 bills; (2) he traveled under a name that did not match the name under which his telephone was listed; (3) his original destination was Miami, a source city of illicit drugs; (4) he stayed in Miami for only forty-eight hours, even though a round-trip flight from Honolulu to Miami takes twenty hours; (5) he appeared nervous during his trip; and (6) he checked no luggage.

Assuming the encounter rises to the level of a stop and police have adequate grounds (reasonable suspicion) to make the stop, what are the police allowed to do? The content of a stop usually involves police briefly questioning the person about his immediate activities or requesting to see some identification or a license. During stops in airports, police often ask to see the person’s ticket.

The stop ends when police let the person go or when the encounter escalates into the more serious type of seizure, an arrest. To define whether a stop has escalated into an arrest, courts have identified several factors. One is the length of time of the stop. Generally stops should be brief, within the twenty-minute range, although courts have steered clear of bright line time limits and have avoided ‘‘rigid criteria’’ in favor of focusing on ordinary human behavior and common sense. Another factor is whether the police moved the person from one location to another. If the police move the defendant, for example, from an airport concourse to a small room, this supports the conclusion that the stop has escalated into an arrest. If the police tell the defendant he is under arrest, again this supports the idea that the stop has become an arrest. (The rationale here is not that police are in charge of characterizing whether the encounter is a stop or an arrest but rather that the impact on the defendant of a police assertion that he is under arrest escalates the encounter from the defendant’s point of view.) Other factors courts have identified include whether the defendant is handcuffed, whether the defendant is moved to an isolated or unfamiliar environment, and whether police are diligent in pursuing investigation during the time the person is detained.

If the encounter does not qualify as a stop (and the Supreme Court has made clear that there can be interactions between citizens and police that do not amount to a stop), then the Fourth Amendment does not apply, and police are free to pursue that activity without explanation. If the encounter does rise to the level of a stop, police must justify the activity by showing reasonable suspicion that crime was occurring. If the encounter escalates from a stop to an arrest, the police face a higher burden to justify the activity, that of probable cause.

On the other hand, if the encounter rises to the level of a stop and police cannot demonstrate reasonable suspicion, or the encounter rises to the level of an arrest and the police cannot demonstrate probable cause, Fourth Amendment law is that any evidence that is a product of the encounter cannot be used against the defendant. For example, assume the police pull over a car by using their lights and siren (a stop). Approaching the driver, the police smell marijuana in the car and see an envelope on the floor labeled ‘‘weed.’’ The police now have probable cause to search the car for drugs. When they search it and find drugs, the defendant is arrested for possession. However, if the police cannot justify the initial stop of the car by showing reasonable suspicion to believe crime was occurring, the drugs cannot be used against the defendant, because the police violated the Fourth Amendment. This ‘‘exclusionary rule’’ is designed to deter police from violating the Fourth Amendment by removing any reward that might flow from a violation.

The Court has extended the same analysis that applies to seizures of persons to apply to seizures of things. So, if police take a person’s baggage in an airport, for example, to expose it to drug-sniffing dogs, the Court will look to whether the seizure of the luggage was brief and nonintrusive enough to qualify as a stop of the luggage or whether the seizure of the baggage was more extensive and commensurate with the type of seizure known as an arrest.


A frisk, also known as a pat-down, occurs when police pat the outside of a person’s clothing. The point of a frisk is to check for weapons, and weapons only. If police frisk a person and feel an object in a pocket that feels like drugs, police may not look in the pocket or take the package. In contrast, if the police feel an object like a knife or a gun, they may take it.

The grounds required before police can frisk a person is reason to believe the person is armed and dangerous. This standard differs from probable cause in two ways. First, in quantity, this level of certainty is less than probable cause. The theory is that because a frisk is less intrusive than a full search, it can be justified on lesser grounds than those required for a full search. Second, in quality, the grounds for a frisk (reason to believe the defendant is armed and dangerous) is also more limited in focus than probable cause. Probable cause to search allows police to search for any type of evidence of crime, including weapons. In contrast, as noted previously, the grounds for a frisk allow police only to look for weapons.

To establish the grounds to believe a person is armed and dangerous, police may rely on reasonable inferences. For example, in the Terry case, the Court held that reason to believe the defendants were armed and dangerous was established because police thought the defendants were walking back and forth, casing a store to set up a robbery. The time was 2:30 in the afternoon. A daylight robbery of a store carries with it a risk that the store clerk will be present and a confrontation will ensue, so grounds to fear a daylight robbery give rise to a reasonable inference that the defendant is armed and dangerous.

Based on reason to believe the defendant is armed and dangerous, police cannot go further than a frisk, in other words, a brief patdown of the person’s outer clothing. Based on those grounds, for example, the police cannot justify reading the documents in a person’s briefcase. In one case, the Court found police conduct to be unconstitutional as exceeding the scope of a permissible frisk when the officers, feeling a small lump in the defendant’s front pocket, determined the lump was crack by squeezing, sliding, and otherwise manipulating the outside of the defendant’s pocket even after it was clear there was no weapon in the pocket. The Court held that the police conduct overstepped the bounds of the strictly circumscribed search for weapons allowed by Terry.

In this same line of cases, the Court has also authorized what might be called a frisk of an automobile. If police stop a suspect in a car, the police are allowed to search the passenger compartment of the car, limited to areas where a weapon could be found, if the police can show a reasonable belief that the suspect is dangerous and the suspect may gain immediate control of a weapon. The theory here is the same as in frisking a person: because the search of the automobile is limited, it may be justified on grounds more limited than the traditional probable cause (Michigan v. Long).

One current controversy raised by the Terry doctrine centers on whether large amounts of drugs will suffice to establish reason to believe the defendant is armed and dangerous. Law enforcement officers argue that if large quantities of drugs are involved, it is reasonable to infer that the drugs are worth a lot of money, and the defendants will be armed and dangerous. The courts generally reject this argument, concluding that while large amounts of drugs would certainly justify a stop of the defendant based on reasonable suspicion that criminal activity is afoot, large amounts of drugs will not justify a frisk of the defendant because the drugs alone will not establish reason to believe the defendant is armed and dangerous.

Overall, the Terry exception to traditional Fourth Amendment doctrine allows police more flexibility in confronting citizens. It has become a well-established feature of Fourth Amendment jurisprudence.


Cases and Statutes Cited

  • Florida v. Bostick, 501 U.S. 429 (1991)
  • Fourth Amendment, U.S. Constitution Illinois v. Wardlow, 528 U.S. 119 (2000)
  • Terry v. Ohio, 392 U.S. 1 (1968)
  • U.S. v. Sokolow, 490 U.S. 1 (1989)

See also Illinois v. Wardlow, 528 U.S. 119 (2000); Race and Criminal Justice; Search (General Definition); Seizures; Terry v. Ohio, 392 U.S. 1 (1968)