During a routine traffic stop, an officer needs a certain amount of time to perform his duties. He must first be satisfied that the driver and occupants do not constitute a threat to themselves or others. Then the officer must obtain information and driving credentials from the driver, verify that neither the vehicle nor its occupants is wanted by other police agencies and complete any tickets and any other documents associated with the stop. Obviously, all of this takes time.
Time is a critical factor during a traffic stop. Although the driver is not under arrest, he or she has been seized within the meaning of the Fourth Amendment and is not free to leave. The defendant is being detained for investigation purposes. Accordingly, the officer does not need probable cause to believe that the operator has committed an offense, nor must the officer inform the driver of his or her constitutional rights prior to questioning. However, the longer the detention period continues, the more the motor vehicle stop will take on the characteristics of an arrest as opposed to a detention. As a result, a court may consider a prolonged detention to have developed into a de facto arrest that must be supported by probable cause. Evidence seized from the operator or statements made during the course of a de facto arrest that is unsupported by probable cause are subject to suppression.
In general, a traffic stop will be considered reasonable if it lasts no longer than is necessary to effectuate its purpose.