In the 2001 case United States v. Christopher Drayton and Clifton Brown, Jr., the U.S. Supreme Court ruled that police officers do not necessarily violate Fourth Amendment rights when they board a bus to ask passengers for their consent to search their luggage or person without any suspicion of illegal activity. The case arose after two men were arrested on drug charges following such a search in Florida; they argued that this constituted an unreasonable seizure under the Fourth Amendment because it was conducted without probable cause or reasonable suspicion. However, by a vote of 6-3, the Supreme Court disagreed with them and upheld their convictions. The majority opinion held that as long as law enforcement officials do not convey a message coercing compliance with their requests, these encounters are considered consensual and thus fall outside the protections of the Fourth Amendment.

In the dissenting opinion for United States v. Christopher Drayton and Clifton Brown, Jr., Justice Souter argued that the police officers' actions constituted a coercive show of authority that would lead reasonable people to believe they were not free to decline officers’ requests or otherwise terminate encounters with them. He emphasized on the Fourth Amendment's protection against unreasonable searches and seizures, stating it should apply in this case as well. The majority’s decision failed to consider how a reasonable person would perceive their freedom in such situations where law enforcement officials board buses and conduct random checks without any specific suspicion of criminal activity. In his view, passengers are likely to feel compelled by uniformed authorities conducting systematic checks within confined spaces like buses, thus making consent involuntary under these circumstances.