Philadelphia has a well-documented problem with pre-textual traffic stops, i.e., when an officer stops a driver for a traffic violation and then extends the duration of the traffic stop to essentially conduct investigations about any potential criminal conduct under the sun. Officers often go on hunches about whether a driver has drugs or other contraband in the car. These hunches are often based on nothing other than a feeling, which can be based on race, gender, etc. The reality is that in Philadelphia, African Americans are pulled over more than any other race. In some cases, drivers get pulled over and stopped for traffic violations, and in other cases, drivers are pulled over for no legitimate reason.

In this article, we examine when a police officer can legally stop a car, in the following situations:

  • mere encounter.
  • investigative detention, and
  • custodial detention.


A mere encounter does not qualify as a seizure. Rather, the citizen is free to talk to the officer or otherwise leave. Here’s an example. A driver is pulled over on the side of the road with a flat tire. A police officer driving by stops to help. The driver can accept the officer’s assistance or otherwise ignore the officer.

Related: Car Searches in Philadelphia Drug/Gun Cases – Legal Rights of the Accused


An investigative detention qualifies as a seizure, but is only a temporary detention. The officer must have reasonable suspicion that criminal activity is occurring. The citizen is not free to leave, but federal and Pennsylvania constitutional laws require that the length of the detention be reasonable.

Example: a police officer observes a driver run a red light. The officer can pull the driver over and issue a ticket. However, the officer cannot extend the duration of the stop by asking the driver where he or she is going, whether there are any drugs or contraband in the car, etc.


A custodial detention is the same thing as an arrest, i.e., a citizen is physically detained by an officer. The officer must have probable cause that a crime was committed by the person detained/arrested.

Example: an officer pulls a car over for a traffic violation. The driver shows clear signs of intoxication. The officer is allowed to arrest the driver for a DUI.

The difference between these three types of traffic stops can be slight. A single fact can turn a mere detention into an investigative detention. Let’s expand on the first example, where the driver is stopped on the side of the road fixing a flat tire. The officer stops and walks over to the driver and asks if the driver needs help changing the tire. As the officer walks up to the car, he smells the odor of crack from a pipe coming from a car window. Now, the officer can conduct an investigative detention, where the driver would not be free to go.


Our law firm handles major felony criminal cases in Philadelphia and the suburbs. If you or a loved one was arrested after a traffic stop, contact our firm. (215) 564-0644