What principle concerning vehicle searches was established in U.S. v. Carney?

The principle established in U.S. v. Carney pertains to the "automobile exception" to the Fourth Amendment's warrant requirement. This case clarifies that if law enforcement has probable cause to believe that a vehicle contains evidence of a crime, they can conduct a warrantless search of that vehicle. The rationale behind this exception is based on the mobility of vehicles and the diminished expectation of privacy individuals have in their vehicles compared to homes.

In this case, the court recognized that the inherent nature of vehicles being movable makes it impractical for officers to obtain a warrant before needing to conduct a search. As a result, if probable cause is present, officers can search the vehicle without a warrant, which is a significant aspect of how officers handle potential evidence in vehicles.

The other options suggest misunderstandings of the legal principles surrounding vehicle searches; for instance, vehicles do not always require a warrant, and the presence of an occupant does not inherently prohibit a search if probable cause exists. Additionally, searches of vehicles are not necessarily subject to stricter rules than those that apply to homes; rather, vehicles enjoy a different legal status regarding privacy and the necessity of warrants, reflecting the practical realities of law enforcement.