The Fourth Amendment to the U.S. Constitution prohibits police from conducting “unreasonable searches and seizures.” And these constitutional protections apply to search and seizures of a vehicle. If police search a vehicle in violation of the Fourth Amendment, any evidence of illegal activity obtained during the search will typically be inadmissible in court. (For more on the exclusion of unlawfully discovered evidence, see What Is the Exclusionary Rule?)
Here are the basics of how courts determine whether a vehicle search was lawful.
(This article is based on U.S. Constitutional law as interpreted by the U.S. Supreme Court. Note that your state’s laws might offer more protections.)
When police stop a vehicle, it is considered a seizure for Fourth Amendment purposes. And for a vehicle search to be justified, the initial stop must have been lawful. In most situations, the legality of a traffic stop turns on whether police had reasonable suspicion to believe the driver broke the law. If police had no legitimate reason to pull the driver over, the stop—and subsequent search—are illegal. There are only limited circumstances—immigration and DUI checkpoints and roadblocks, for example—that allow law enforcement to detain vehicles without reasonable suspicion.
(For a more in-depth discussion on vehicle detentions, see Traffic Stops, Roadblocks, and Checkpoints: What’s the Law?)
A traffic violation generally doesn’t give police the right to search the inside of an automobile. Police must have probable cause that the car contains evidence of criminal activity (like drugs or illegal weapons) to conduct a search.
But there are several exceptions to the probable cause rule. For instance, police can search a car if the driver consents. And the laws of many states authorize police to arrest drivers for minor traffic violations. When police arrest a motorist and tow the car, they can generally do an “inventory search” of the car’s contents. The legality of a search, however, always depends on the facts of the case.
(For a more in-depth discussion of this issue, see our article on vehicle searches.)
Get in Touch With a Lawyer
If you’re accused of committing a crime, talk to an experienced criminal defense attorney. Search-and-seizure law is complicated and frequently changes. A qualified criminal lawyer can tell you how the law applies to your situation and whether you have any viable defenses.