President Trump cannot block users from viewing his profile on Twitter as it violates free speech rights, says court.

A US judge has ruled President Donald Trump cannot legally block Twitter users because doing so violates their right to free speech.

District Judge Naomi Reice Buchwald said on Wednesday the president’s Twitter account – @RealDonaldTrump – was a “designated public forum” open to all US citizens.

The account has 52.2 million followers and Trump uses it for a variety of policy announcements.

The case against the president was brought by the Knight First Amendment Institute at Columbia University and seven individuals blocked by Trump after they criticised him.

When one Twitter user blocks another, the blocked user may not respond to the blocker’s tweets on the social media platform.

Media reports say among those Trump has blocked are novelists Stephen King and Anne Rice, comedian Rosie O’Donnell, model Chrissy Teigen, actress Marina Sirtis, and the military veterans political action committee VoteVets.org.

‘Viewpoint discrimination’

Judge Buchwald, in a 75-page opinion, said the blocking of Trump’s critics violated the free speech rights of those users guaranteed in the US Constitution’s First Amendment.

The judge said the users “were indisputably blocked as a result of viewpoint discrimination” and this was “impermissible under the First Amendment”.

The US Department of Justice, which represents the president in the case, said it disagreed with the ruling and is considering the next steps.

Lawyers for the president argued Trump’s own First Amendment rights allowed him to block people with whom he did not wish to interact.

Buchwald rejected that.

“While we must recognise, and are sensitive to, the president’s personal First Amendment rights, he cannot exercise those rights in a way that infringes the corresponding First Amendment rights of those who have criticised him,” she said.

Mute users

The judge stopped short of ordering Trump to unblock users, saying it was not necessary to enter a “legal thicket” involving courts’ power.

She said she assumed Trump or his social media director Dan Scavino, who also was a defendant in the case, would unblock the users in light of her decision.

Buchwald said Trump could “mute” users, meaning he would not see their tweets while they could still respond to his, without violating their free speech rights.

Eugene Volokh – a University of California Los Angeles School of Law professor who specialises in First Amendment issues – said the decision’s effect would reach beyond Trump.

“It would end up applying to a wide range of government officials throughout the country,” he said.