The institute represented seven individuals who had been blocked by account.
“We’re pleased with the court’s decision,” said Jameel Jaffer, the Knight Institute’s executive director. “The president’s practice of blocking critics on Twitter is pernicious and unconstitutional, and we hope this ruling will bring it to an end.”
There was no immediate response to the ruling from the White House.
The lawsuit was filed last July against Trump and two of his aides, White House social media director Dan Scavino and then-White House press secretary Sean Spicer. It argued that Trump’s account constituted a public forum under the First Amendment, and that the White House was violating the plaintiffs’ First Amendment right to petition their government for redress of grievances.
The plaintiffs were: a university professor in Maryland, a surgery resident in Tennessee, a Washington state songwriter, a New York comedy writer, an author, a legal analyst and a police officer.
Trump, an avid Twitter user, frequently stokes controversy on social media.
In the past week, he has repeatedly claimed in multiple tweets that the Justice Department put a “spy” inside his presidential campaign to frame him for “crimes he didn’t commit” amid mounting questions over his campaign’s possible collusion with Russia.
The tweets prompted a reply from ex-FBI Director James Comey, who was fired by Trump last year. Comey tweeted on Wednesday: “Attacks on the FBI and lying about its work will do lasting damage to our country.”