The California Supreme Court says the public has the right to access emails and text messages about government business sent on California officials' private accounts.
The ruling by a unanimous court on Thursday clears up a murky area of law in the Golden State.
The use of private email accounts by public officials has faced scrutiny in recent years, with some using it as a way to avoid disclosure. Many states treat those emails as public records.
But opponents have raised privacy concerns. They say public officials sometimes need confidentiality to discuss unpopular views.
The lawsuit before the California Supreme Court dates back to 2009 and involved messages on private devices used by San Jose's mayor and members of the city council.