United States v. Robinson

The Supreme Court's ruling in Whren v. United States (1996), which gave police broad power to use even minor traffic violations as justification for pulling over motorists and searching their cars for drugs cited United States v. Robinson as a precedent. Under Whren's unanimous ruling, once a car is stopped because of a traffic violation, police may ask the driver questions and visually search the passenger compartment. If officers suspect a weapon is in the car, they can physically search the entire car. Justice Antonin Scalia wrote in that opinion:

We flatly dismissed the idea that an ulterior motive might serve to strip the agents of their legal justification. In United States v. Robinson . . . we held that a traffic-violation arrest (of the sort here) would not be rendered invalid by the fact that it was "a mere pretext for a narcotics search," and that a lawful post-arrest search of the person would not be rendered invalid by the fact that it was not motivated by the officer-safety concern that justifies such searches.

Scalia quoted from the Robinson case: "Since it is the fact of custodial arrest which gives rise to the authority to search, it is of no moment that [the officer] did not indicate any subjective fear of the [arrestee] or that he did not himself suspect that [the arrestee] was armed."