Traffic stops

A traffic stop, commonly called being pulled over, is a temporary detention of a driver of a vehicle by police to investigate a possible crime or minor violation of law.

In constitutional law in the United States, a traffic stop is considered to be a subset of the Terry stop; the standard set by the United States Supreme Court in Terry v. Ohio regarding temporary detentions requires only reasonable suspicion that a crime has occurred or is about to occur.

A stop is usually accomplished through a process known as "pulling over" the suspect's vehicle. Police vehicles (except those used by undercover personnel) traditionally have sirens, loudspeakers, and lightbars that rotate or flash. These devices are used by the officer to get the attention of the suspect and to signal that they are expected to move over to the shoulder and stop. Failure to comply could result in citation of failure to yield to an emergency vehicle and possibly raise suspicion that the driver is attempting to flee.

These devices are also typically equipped on other emergency vehicles such as fire trucks and ambulances, and in all cases, such signals and the laws requiring that other vehicles pull to the shoulder allow the emergency vehicles to pass other traffic safely and efficiently when responding to emergency situations. In the case of a traffic stop, the officer pulls the patrol vehicle behind the subject vehicle as it stops instead of proceeding past as he or she would during other emergency responses.

Depending upon the severity of the offense which the officer believes to have occurred, the officer may either arrest the suspect, by taking him or her to jail, or check for any outstanding warrants before issuing a citation also called a notice to appear or summons in some jurisdictions, which is essentially a traffic ticket. In some cases, officers may choose to simply issue a verbal or written warning.

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