It is unconstitutional for public officials, including the president, to block Twitter followers who criticize them, a court ruled today in a legal dispute over President Trump’s account.

Twitter’s “interactive space” creates a public forum

The lawsuit, brought by Columbia University’s Knight First Amendment Institute, argued that Twitter users blocked by @realdonaldtrump had their First Amendment rights violated. In a decision released today, a federal judge hearing the case ruled that Twitter’s “interactive space,” where users can interact with Trump’s tweets, qualifies as a public forum, and that blocking users unconstitutionally restricts their speech. The decision rejected arguments from the president’s team that President Trump’s own First Amendment rights would be violated if he could not block users.

“This case requires us to consider whether a public official may, consistent with the First Amendment, ‘block’ a person from his Twitter account in response to the political views that person has expressed, and whether the analysis differs because that public official is the President of the United States,” the decision begins. “The answer to both questions is no.”

The court, while not going so far as to enter an order against the president and social media director Dan Scavino specifically, ruled more generally that public officials violated users’ rights when blocking them on the platform. The decision says such action is “viewpoint discrimination,” and that “no government official — including the President — is above the law, and all government officials are presumed to follow the law as has been declared.”

“We respectfully disagree with the court’s decision and are considering our next steps,” a spokesperson for the Justice Department said in a statement.

Notably, the decision distinguished between Twitter’s block and mute functions, and the judge found the argument that the two functions were equivalent “unpersuasive.” Users can still reply to tweets after they’ve been muted, even if those replies are never seen, the ruling pointed out. The judge hinted at that line of reasoning in March.

The lawsuit, first filed last year, has been a closely watched test of First Amendment rights in the digital age, and one that took on a special relevance, as it was focused on the president’s preferred megaphone.

Update, 3:05 PM ET: Includes statement from Justice Department.