In the case of Marcus Thornton v. United States, 2003, the U.S Supreme Court ruled in favor of the United States. The issue at hand was whether a police officer's search of Thornton's car after arresting him for drug possession violated his Fourth Amendment rights against unreasonable searches and seizures. The court held that an officer making a lawful arrest has the right to search any area within immediate control of the suspect, including their vehicle even if they had already exited it prior to arrest - extending previous rulings which allowed such searches only when suspects were arrested while inside their vehicles (Belton rule). This decision expanded law enforcement’s ability to conduct warrantless vehicle searches incident to arrests.

In the dissenting opinion for Marcus Thornton v. United States, Justice Scalia argued that the majority's decision expanded police powers beyond what was intended by previous rulings. He contended that prior cases allowed officers to search a vehicle incident to arrest only if it was reasonable to believe evidence relevant to the crime of arrest might be found in the vehicle or if the arrested person could access his vehicle at time of search and pose a risk. In this case, Thornton had already exited his car before being approached by an officer; therefore, he posed no immediate threat nor could he destroy any potential evidence within his car. Thus, Scalia believed there were no grounds for a warrantless search under these circumstances and considered such searches as violations of Fourth Amendment protections against unreasonable searches and seizures.