The decision comes in response to a lawsuit filed by seven people, including local standup comic Nicholas Pappas, who claimed the presidential block caused "irreparable injury to their First Amendment rights".
"The President's practice of blocking critics on Twitter is pernicious and unconstitutional, and we hope this ruling will bring it to an end", he said.
One of the users blocked by Trump, according to the letter, was Holly O'Reilly, whose @AynRandPaulRand account was blocked in May 2017 after posting a GIF of Pope Francis glancing at Trump with a troubled expression, above which she wrote, "This is pretty much how the whole world sees you".
No matter what your political views are, I think we can all agree that the fact we live in a country where former reality TV star, and current United States president, Donald Trump may be held in contempt of court for not unblocking Stephen King on Twitter is reason enough to take a step back and examine ourselves, as a nation.
US President Donald Trump has made directing scorn on Twitter a defining feature of his presidency. "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".
The White House has not commented on the case, and the Justice Department is reviewing its options, which could include an appeal.
M&S shuts 14 more stores as profits slide
This is despite it opening more full line (clothing, home and food) department stores and adding more space during the period. M&S would close more than 100 stores that sell both clothing and food by 2022, the company said in a statement on Tuesday.
"Because of the way the President and his aides use the @realDonaldTrump Twitter account, the account is a public forum under the First Amendment", the lawsuit states. He has blocked many critics from his account, which prevents them from directly responding to his tweets.
Per the court decision, Trump is legally obligated to immediately unblock anyone that he's blocked, even on his personal account, as soon as possible. But blocking someone also works in the other direction: if Trump blocks another user, that user can't see Trump's tweets and (as a consequence) can't reply to them.
"The judge pointed to a number of ways in which the Twitter account has been used for governmental purposes, and that's really the question", said Michael McConnell, who teaches First Amendment law at Stanford Law School.
Enlarge / These Twitter users are participating in a constitutionally protected public forum, a federal judge has ruled.
"No government official - including the President - is above the law", wrote Buchwald for the U.S. District Court for the Southern District of NY.
Could this impact Twitter users in Australia?
"We do not suggest that the impact on the individual plaintiffs ... is of the highest magnitude", Buchwald's ruling reads. The judge dismissed Sarah Huckabee Sanders as a defendant in the case after it was established she does not have access to Trump's account. At that time, Judge Buchwald urged both parties to find a resolution outside of court.