President Donald Trump may not legally block Twitter users because doing so violates their right to free speech, a federal judge in New York has ruled.
United States District Judge Naomi Reice Buchwald's ruling came in response to a lawsuit filed against Mr Trump by the Knight First Amendment Institute at Columbia University and several Twitter users.
Here's how the case unfolded and what it means for the President.
Mr Trump has made tweeting from his @realDonaldTrump account an integral and controversial part of his presidency.
Aides have reportedly tried to rein in his tweeting, which often starts early in the morning.
But he has remained unfettered and used Twitter to promote his agenda, announce policy and attack critics, especially the media, and the investigation into possible Russian connections with his campaign.
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.
When one Twitter user blocks another, the blocked user may not respond to the blocker's tweets on the social media platform.
The Knight First Amendment Institute and the individual Twitter users claimed that by blocking users for their views, Mr Trump was shutting them out of discussion in a public forum, violating the First Amendment.
The US Department of Justice, which represented the President in the case, argued Mr Trump's own First Amendment rights allowed him to block people with whom he did not wish to interact.
But Justice Buchwald rejected that argument and agreed with the plaintiffs' contention that the discussions arising from Mr Trump's tweets should be considered a public forum.
"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," Judge Buchwald said.
In addition to Mr Trump, the lawsuit named Dan Scavino, the President's social media director, as a defendant.
While she said the President should "remedy the blocking", Judge Buchwald stopped short of directly ordering Mr Trump to unblock users.
"Because no government official is above the law and because all government officials are presumed to follow the law once the judiciary has said what the law is, we must assume that the President and Scavino will remedy the blocking we have held to be unconstitutional," she wrote.
She said the President could "mute" users, meaning he would not see their tweets while they could still respond to his.
The Justice Department and Twitter are yet to comment on the ruling.
Mr Trump has also not yet spoken (or tweeted) about Judge Buchwald's decision.