Pennsylvania v. Mimms, 434 U.S. 106 (1977), is a United States Supreme Court criminal law decision holding that a police officer ordering a person out of a car following a traffic stop and conducting a pat-down to check for weapons did not violate the Fourth Amendment to the United States Constitution.

The conviction was reversed by the Pennsylvania Supreme Court (PSC) on March 31, 1975, which ruled that the evidence should have been suppressed because the police had violated Mimms's Fourth Amendment rights against unlawful search and seizure.

[1] The Court in Terry v. Ohio stated, "the facts available to the officer at the moment of the seizure or the search 'warrant a man of reasonable caution in the belief' that the action taken was appropriate."

In a 6–3 per curiam ruling, the U.S. Supreme Court decided against Mimms, holding that the order to exit the car was reasonable and thus did not violate the Fourth Amendment.

The court reversed the ruling because the "revolver was seized in a manner which violated the Fourth Amendment to the Constitution of the United States."

[5] While on patrol in the city of Philadelphia, two officers discovered Harry Mimms on the road, driving a vehicle with an expired license plate.

The Pennsylvania Supreme Court saw no problem in the actions that involved pulling the car over and stated that due to observation of a bulge under the respondent's coat, the search was permissible.

The only thing to decide, besides the "pat down," is whether the initial authorization by the officer to tell the respondent to exit the vehicle was allowed under the Fourth Amendment.

Another reason for making the action taken by the officer to ask the respondent to exit the vehicle more acceptable was that it could prevent an accidental mishap from oncoming cars.

The case of Terry v. Ohio stated that "the facts available to the officer at the moment of the seizure or the search ‘warrant a man of reasonable caution in the belief that the action taken was appropriate.

[5] Justice Thurgood Marshall wrote a dissenting opinion, stating that the frisk that the officer proceeded to do to Mimms could be permissible under the Fourth Amendment only if the search was the reason for the stop.

Justices John Paul Stevens and William Brennan wrote a different dissent, stating that the court gave too much leeway in allowing the officers to search the defendant for any reason of concern.