A federal appeals court just struck a massive victory for freedom of speech.

On Friday afternoon, in a brilliantly argued 90-page decision, the Fifth Circuit Court of Appeals ruled in favor of a Texas law stopping the biggest social media companies from censoring their users.

The ruling will likely be appealed to the Supreme Court, setting up a hugely important battle. If the high court confirms the Fifth Circuit’s view, companies like Twitter will mostly lose the power to censor their users for legal speech. If not, their censorship could become even more aggressive.