The California Supreme Court will decide whether Facebook and other social media companies must turn over user content to criminal defendants.
The justices are expected to rule today in a case that has pitted some of Silicon Valley's biggest companies against public defenders.
At issue are requests by a defendant charged with murder in San Francisco for videos and other content posted to Facebook and Instagram by the victim and a witness. Lee Sullivan and a co-defendant also sought information from Twitter.
The defendants say their constitutional right to a fair trial entitles them to the material to prepare their case.
Attorneys for the companies say a federal privacy law prevents the release of user content, and the defendants have other ways to get the material.