Investigative Detention

Fundamentals of Procedural Law by Adam J. McKee

An investigative detention, commonly referred to as a Terry stop (from the landmark case Terry v. Ohio, 392 U.S. 1, 1968), is a brief detention of a person by law enforcement officers for investigation. The purpose is to confirm or dispel the officer’s suspicion that criminal activity may be afoot. During this stop, officers do not need full probable cause that would be required for an arrest, but they need a reasonable suspicion based on specific, articulable facts.

When Investigative Detentions Occur

A typical scenario for an investigative detention would be when a police officer observes behavior that is suspicious but doesn’t rise to the level of probable cause for an arrest. For example, if a person is lurking near a closed store late at night, an officer might stop this person to inquire about their actions.

Terry Stop and Frisk

During an investigative detention, if an officer has a reasonable belief that the person is armed and dangerous, they can perform a frisk. This is a quick pat-down of the person’s outer clothing to search for weapons for the safety of the officer and others nearby (Terry v. Ohio, 1968).

Development of Investigative Detention from Terry

Investigative detentions, also known as Terry stops, find their roots in the landmark Supreme Court case Terry v. Ohio. The main issue in Terry was the protection of law enforcement officers from potential harm during an encounter with a suspect. The Supreme Court held that an officer, given reasonable suspicion that a person may be armed and presently dangerous, could perform a “stop and frisk” – a brief stop and a pat-down search for weapons.

Initially, the Court’s decision in Terry was driven by the need for the immediate safety of the officer. The officer, in Terry, had observed the suspects seemingly “casing” a store for a potential robbery. He detained and frisked them, discovering concealed weapons, thus substantiating the concern for officer safety.

The concept of a “stop and frisk” gradually expanded into the broader idea of “investigative detentions.” These are brief detentions that allow law enforcement officers to investigate suspicious behavior that doesn’t quite rise to the level of probable cause for an arrest but is more than a mere hunch.

In subsequent rulings, the Supreme Court clarified and expanded on the Terry decision. For instance, in Adams v. Williams, 407 U.S. 143 (1972), the Court acknowledged that a brief stop of a suspicious individual can be most reasonable in light of facts known to the officer at the time.

Over time, the principles of Terry v. Ohio have evolved into an essential tool for law enforcement. It allows officers to briefly detain individuals for investigation based on a reasonable suspicion of criminal activity, all the while balancing this law enforcement necessity against individuals’ Fourth Amendment rights against unreasonable searches and seizures.

Duration of Investigative Detentions

In the realm of investigative detentions, two vital elements help define the legality of these interactions: the standard of reasonable suspicion and the acceptable duration of the detention.

Reasonable suspicion is a standard established by the Supreme Court in Terry v. Ohio (1968). It is a lesser requirement than probable cause, which is needed for an arrest. Reasonable suspicion means that the law enforcement officer has a well-founded belief based on specific, factual circumstances that criminal activity is happening.

The officer must be able to articulate what these facts are and why they led to suspicion. This could include abnormal behavior, a suspect fitting a certain description, a credible tip, or something else that would make an experienced officer suspicious.

The duration of an investigative detention is also a critical factor in its legality. The Supreme Court in United States v. Place, 462 U.S. 696 (1983), noted that the length of detention must be brief and not extend beyond the time needed to confirm or dispel the officer’s suspicions.

But how long is “brief”? While the Supreme Court hasn’t given a specific time limit, most jurisdictions interpret “brief” to mean around 20 minutes or less. However, this isn’t a strict rule, and each case’s circumstances can affect the acceptable length. For instance, a detention could be deemed reasonable if it lasted longer due to factors beyond the officer’s control, such as waiting for a K-9 unit to arrive.  Various state Couts have clarified for local officers, often specifying rules in the jurisdiction’s Rules of Criminal Procedure.

On the flip side, if an investigative detention lasts too long or becomes too intrusive, it could be considered a de facto arrest requiring probable cause. The key is maintaining a balance between the need for law enforcement to investigate possible criminal activity and respecting the individual’s Fourth Amendment rights against unreasonable searches and seizures.

The Arkansas Example
Arkansas Rules of Criminal Procedure, Rule 3.1, titled “Stopping of Suspect,” provides the following:

A law enforcement officer lawfully present in any place may, in the performance of his duties, stop and detain any person who he reasonably suspects is committing, has committed, or is about to commit (1) a felony, or (2) a misdemeanor involving danger of forcible injury to persons or of appropriation of or damage to property, if such action is reasonably necessary either to obtain or verify the identification of the person or to determine the lawfulness of his conduct. An officer acting under this rule may require the person to remain in or near such place in the officer’s presence for a period of not more than fifteen (15) minutes or for such time as is reasonable under the circumstances. At the end of such period the person detained shall be released without further restraint, or arrested and charged with an offense.

Landmark Cases on Investigative Detentions

Investigative detentions, often known as Terry stops, have a rich legal history defined by several landmark cases.

Terry v. Ohio (1968)

The foundation of investigative detentions lies in the Supreme Court’s ruling in Terry v. Ohio.  The Court held that the Fourth Amendment allows a reasonable search for weapons for the protection of the police officer, where the officer has reason to believe that he is dealing with an armed and dangerous individual, regardless of whether he has probable cause to arrest the individual for a crime.

Adams v. Williams, 407 U.S. 143 (1972)

In Adams v. Williams, the Court reaffirmed the principles of Terry, stating that a brief stop of a suspicious individual may be most reasonable in light of the facts known to the officer at the time.

United States v. Place, 462 U.S. 696 (1983)

In United States v. Place, the Court held that a 90-minute detention of luggage at an airport exceeded the permissible duration for investigative detention, emphasizing that investigative detentions must be “swiftly developing.”

Illinois v. Wardlow (2000)

Illinois v. Wardlow clarified that flight in a high crime area could be considered suspicious behavior justifying investigative detention. In this case, the Court ruled that the officer acted reasonably because flight at the sight of law enforcement might suggest the individual is involved in criminal activity.

Hiibel (2004)

Hiibel v. Sixth Judicial District Court of Nevada raised the issue of identification during a Terry stop. The Court held that a state law requiring a suspect to disclose his name during a valid Terry stop was reasonable under the Fourth Amendment.

These landmark cases collectively shape the legal landscape of investigative detentions, illustrating the delicate balance between the needs of law enforcement and the individual rights protected by the Fourth Amendment.


Investigative detentions, often known as Terry stops, are brief detentions by law enforcement for the purpose of investigating suspicious behavior that does not meet the threshold for an arrest. The standard for these stops is reasonable suspicion. If the officer has a reasonable belief that the person is armed, they can conduct a frisk.

However, these detentions must be brief and not extend beyond the time necessary to confirm or dispel the officer’s suspicion. Understanding this procedural law principle can help in striking a balance between effective law enforcement and the protection of civil liberties.

Modification History

File Created:  08/07/2018

Last Modified:  07/13/2023

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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