The Fourth Amendment of the United States Constitution prohibits a person from being stopped or detained without evidence that he or she was involved in a crime. This should protect people from being the victims of unfair pretextual traffic stops*. Unfortunately, as incidents of racial profiling were escalating, the United States Supreme Court's interpretation of the Fourth Amendment was becoming less protective of individuals' rights.
The Court's first major decision on the constitutionality of pretextual traffic stops was in the 1996 court case Whren v. U.S. The Justices were presented with the question of whether or not a vehicle search is constitutional if it wouldn't have taken place unless the police had sought an unrelated excuse for the search. The Court decided that any traffic violation by a driver was a sufficient reason for a stop, regardless of the officer's true intentions or motivations. With traffic laws as confusing as they are, this decision allows police to stop almost any driver and can subject him or her to a plain-view search at the whim of the police officer.
Later Court decisions only reinforced the justices' initial ruling:
* A pretextual traffic stop is one in which an officer uses a minor traffic infraction as a pretext to pull over a motorist, even though the officer's real intention was to stop the driver for an unrelated reason, such as the person's race or ethnicity.