Ybarra v. Illinois

Police had a warrant to search a bar and its bartender for evidence of drug activity, but instead searched every patron present, including Ybarra (defendant), finding heroin in his pocket. The warrant named only the bar and bartender — no patrons were mentioned. The trial court admitted the heroin, and Ybarra was convicted.

Whether a person's mere proximity to others independently suspected of criminal activity gives rise to probable cause to search that person.