The seven plaintiffs believed "that his or her personal First Amendment rights have been and will continue to be encumbered, and the ability to communicate has been and will be limited because of each individual plaintiff's personal ownership of a Twitter account that was blocked" by Trump, Buchwald wrote.
While presidents retain their own First Amendment rights even when they take public office, the judge said, Trump "cannot exercise those rights in a way that infringes the corresponding First Amendment rights of those who have criticized him". The viewpoint-based exclusion of the individual plaintiffs from that designated public forum 1s proscribed by the First Amendment and can not be justified by the President's personal First Amendment interests.
White House press secretary Sarah Sanders and former White House communications director Hope Hicks, both of whom were named in the suit, were dismissed as defendants. They claimed the president uses Twitter as a public forum to share official information in his capacity as president and therefore was violating their right to petition the government by blocking them.
The administration had sought to argue that Trump was within his personal rights to block certain accounts and that blocked individuals could still access Trump's Twitter feed.
If Donald Trump blocks someone, that person loses the opportunity to reply to Trump tweets and have their tweet show up underneath them. Importantly, the ruling identifies only parts of Trump's account as a public forum subject to First Amendment protections, not the entire account nor the rest of Twitter.
"We must assume that the President and Scavino will remedy the blocking we have held to be unconstitutional", she wrote.
The Department of Justice said in a statement that it "respectfully" disagrees with the ruling and is considering how to proceed.
"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", writes Buchwald.
By blocking users, Trump prevented them from speaking to others on the reply thread, not just to him, the judge said.
The distinction between muting and blocking showed the judge applied a subtle, but sophisticated, understanding of Twitter and social media, said Aaron Caplan, a professor at Loyola Law School of Los Angeles specialising in constitutional law.
When a Twitter user is blocked by another, he or she can not see the blocked user's tweets or replies, or interact with that user.
"This is a great precedent we have set for politicians that decide to use social media as a town hall to be held accountable to the rules of the First Amendment", Gu said. The defendants apparently tried to say injunctive relief (meaning a court-ordered act or prohibition of an act, like to demand Trump stop blocking or unblock users) "cannot ever be awarded against the President".
If Twitter is a public forum where users have First Amendment rights, that could make Twitter bans unconstitutional as well.
Could this impact Twitter users in Australia?
However, the Federal District Court for the Southern District of NY found that this was not the case.