Can police search my phone or car without a warrant in California?

Phones: almost never, Riley v. California (2014) 573 U.S. 373 requires a warrant even after arrest, and California's Electronic Communications Privacy Act (Penal Code section 1546 et seq.) adds statutory protection. Cars: the automobile exception permits a warrantless search on probable cause that the vehicle contains evidence or contraband. Consent, which may be declined, makes any search lawful.

The two objects sit at opposite ends of Fourth Amendment law. Cell phones receive maximum protection: Riley v. California (2014) 573 U.S. 373 holds that the vast data on a phone cannot be searched incident to arrest (a warrant is required), and California's Electronic Communications Privacy Act (Penal Code section 1546 et seq.) requires a warrant or valid consent for government access to device data, with suppression as a remedy. Vehicles receive less: under the automobile exception, officers with probable cause to believe a car contains evidence or contraband may search it and containers within it without a warrant, and lawful impounds bring inventory searches. Since legalization, the odor or presence of a lawful amount of cannabis, standing alone, has diminished force as probable cause. Cross-cutting rules matter most in practice: consent eliminates the warrant requirement and may be declined; probation and parole search conditions authorize searches otherwise unlawful; and evidence from an unlawful search is challenged by suppression motion under Penal Code section 1538.5.

Authority: Riley v. California (2014) 573 U.S. 373