President Donald Trump can use Twitter how he sees fit and is free to block anyone he wants, according to the Justice Department.

Department of Justice Attorney Michael Baer wrote on Friday to the New York judge overseeing a lawsuit claiming President Trump can’t block anyone on Twitter to explain the “uncharted waters” it would send the First Amendment into if the president were forced to use social media in a certain way.

“It would send the First Amendment deep into uncharted waters to hold that a president’s choices about whom to follow, and whom to block, on Twitter—a privately run website that, as a central feature of its social-media platform, enables all users to block particular individuals from viewing posts—violate the Constitution,” claimed Baer in his letter. “To the extent that the President’s management of his Twitter account constitutes state action, it is unquestionably action that lies within his discretion as Chief Executive; it is therefore outside the scope of judicial enforcement.”

Baer also added that it “would raise profound separation-of-powers concerns by intruding directly into the president’s chosen means of communicating to millions of Americans.”

A group of left-wing Twitter users is currently suing the president, claiming that he unlawfully blocked them on the social network.

The users argue that the Constitution prohibits the president from blocking people on Twitter and other social media platforms, citing the fact that he makes statements relating to public policy, thus making his account a “public forum.”