Chalk up a win for criminal defendants and a loss for social media companies.

the California Supreme Court ruled unanimously that Facebook and other social media companies have to turn over communications in response to subpoenas.

The ruling, a victory for the criminal defense bar, overturned an appeals court decision that said defense lawyers could not force media companies to comply with such subpoenas prior to trial.

Defense lawyers have been fighting since 2008 to be able to have access to social media accounts to defend their clients. The media companies have refused access, saying a federal privacy law barred cooperation except in limited circumstances.

Police and prosecutors, though, are able to obtain the communications through warrants and subpoenas.

So what does the ruling mean to criminal defendants? In a lot of cases, defense attorneys will use social media postings either to prove innocence or, in many cases, prove intent-or lack thereof. That information can be crucial, especially with specific charges where lak of intent is the backbone of a defense case.

While public communications on social media are available before trial, until now they’ve been inadmissible at trial until the social media company or user authenticate the posting.

The California Supreme Court has made it easier to introduce the evidence and given criminal defense attorneys a boost.

You can read more about the ruling here.