The answer in most cases is yes. Police will usually need a warrant to conduct a search of your computer or hard drive under California law. 

As the U.S. Supreme Court recently recognized in the case of Riley v. California, electronic devices often contain a "record of nearly every aspect of [people's] lives." As a result, we have an important right of privacy in our computers.

This means that most police searches of computers require a search warrant under California search warrant law. To get a warrant, police must go to a judge and show probable cause to believe the search will yield evidence about a crime.

BUT there are important exceptions to this rule. Police can search or seize your computer, tablet, or flash drive without a warrant if:

1. You consent to the search or seizure;
2. Someone else with authority over the device consents--this can be your roommate or family member, or your employer when it is your work computer;
3. There is a genuine emergency justifying the search;
4. You are taking the computer across an international border; or
5. The police have reason to believe the evidence on the computer will be destroyed if they don't seize it.

Learn more about California search and seizure laws. Regarding cell phone searches, refer to our blog post on whether police can search cell phones following arrest in California.