SAN JOSE, Calif. — President Donald Trump cannot block his critics on Twitter, a federal appeals court ruled Tuesday in a case that could affect officials’ communications with the public on social media.

“The First Amendment does not permit a public official who utilizes a social media account for all manner of official purposes to exclude persons from an otherwise-open online dialogue because they expressed views with which the official disagrees,” wrote Judge Barrington Parker in the unanimous decision by the three-member U.S. Court of Appeals for the 2nd Circuit in New York.

The president had appealed last year’s court ruling that his blocking of critics on Twitter was unconstitutional. The lawsuit was brought in 2017 by the Knight First Amendment Institute at Columbia University on behalf of seven Twitter users who said Trump blocked them after they tweeted something critical at or about him.

“With public officials across the country increasingly using social media to communicate with and foster debate among their constituents, today’s decision should make them think twice before hitting the block button when they don’t like what someone has posted,” said Katie Fallow, senior staff attorney at the Knight Institute, in a statement Tuesday.

Trump, who has more than 61 million followers on his @realDonaldTrump Twitter account, has said his tweets allow him to reach his constituents directly. While he also gained an official @POTUS account after he became president, he regularly makes announcements about government business on his longtime personal account.

In the appeals court ruling, Parker wrote: “We do not consider or decide whether an elected official violates the Constitution by excluding persons from a wholly private social media account. Nor do we consider or decide whether private social media companies are bound by the First Amendment when policing their platforms.”

This is the second time this year that a federal appeals court has ruled on a case involving social media interactions between a public official and constituents. In January, in a case also brought by the Knight Institute, the U.S. Court of Appeals for the 4th Circuit ruled in favor of a Virginia man who was temporarily blocked from the Facebook page of the chair of a county board of supervisors.

The president’s office has not responded to a request for comment.