Police can search your vehicle for a number of reasons. Their most common justifications for rifling through your car are,
- probable cause to believe you’ve committed a crime,
- search incident to your arrest, and
- search or “inventory” prior to towing your vehicle.
If police have grounds to search a car, they can also search the passenger’s belongs.
Say, for instance, a male driver is pulled over with his girlfriend in the passenger seat. The police see drug paraphernalia in plain view as they’re speaking to the driver. They lawfully arrest the man and order the passenger out of the vehicle. The cops can now conduct a “search incident to arrest.” If the female’s purse is in the car, police can (and certainly will) search it.
According to the U.S. Supreme Judicial Court, such a search does not violate the 4th Amendment..
When there is probable cause to search for contraband in a car, it is reasonable for police officers-like customs officials in the founding era-to examine packages and containers without a showing of individualized probable cause for each one. A passenger’s personal belongings, just like the driver’s belongings or containers attached to the car like a glove compartment, are “in” the car, and the officer has probable cause to search for contraband in the car.
Wyoming v. Houghton, 526 U.S. 295, 302 (1999).
This does not, however, give police authority to search the passenger’s person. To conduct an individualized search of the passenger, police must have additional justification.