A federal appeals court upheld a Texas law on Friday that seeks to curb censorship by social media platforms. The ruling, a major victory for Republicans who charge companies like Twitter and Facebook are limiting free speech, is a step in a major legal battle that could end up at the Supreme Court.

The lawsuit is challenging HB 20, a Texas bill signed into law by Gov. Greg Abbott that regulates social media platforms with more than 50 million monthly users, which includes Google, Facebook and Twitter, and says they cannot censor or limit users' speech based on viewpoint expression. 

In his opinion, Federal Judge Andrew S. Oldham of the Fifth Circuit said the platforms argued for "a rather odd inversion of the First Amendment" that "buried somewhere in the person's enumerated right to free speech lies a corporation's unenumerated right to muzzle speech."