At the end of May I did a post about Are Arizona legislators blocking you on Twitter? Let Blog for Arizona know, which gave you the background on a case of first impression:

You may recall that in May 2018, A federal judge in New York ruled that President Trump may not block users from following his Twitter account because the social media platform is a “public forum” protected by the First Amendment. Donald Trump cannot block critical Twitter users, court rules:

“Blocking of the individual plaintiffs as a result of the political views they have expressed is impermissible under the First Amendment,” Judge Naomi Reice Buchwald wrote in the decision.

“While we must recognize, 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 criticized him,” she wrote.

The Justice Department filed an appeal to the 2nd U.S. Circuit Court of Appeals in Manhattan. The Justice Department at oral argument in March 2019 argued that Trump acts as private citizen when blocking Twitter followers. But a panel of Manhattan federal appeals judges reacted with skepticism to Justice Department arguments that President Donald Trump should be free to block followers from his Twitter feed because it’s a personal account, not a public forum. Appeals court hears arguments on Trump’s Twitter blocks. The judges didn’t say when they will rule.

Today’s that day. The New York Times reports, Trump Can’t Block Critics From His Twitter Account, Appeals Court Rules:

President Trump has been violating the Constitution by blocking people from following his Twitter account because they criticized or mocked him, a federal appeals court ruled on Tuesday. The ruling(.pdf) could have broader implications for how the First Amendment applies to the social-media era.

Because Mr. Trump uses Twitter to conduct government business, he cannot exclude some Americans from reading his posts — and engaging in conversations in the replies to them — because he does not like their views, a three-judge panel on the United States Court of Appeals for the Second Circuit ruled unanimously.

Writing for the panel, Judge Barrington D. Parker noted that the conduct of the government and its officials are subject today to a “wide-open, robust debate” that “generates a level of passion and intensity the likes of which have rarely been seen.”

The First Amendment prohibits an official who uses a social media account for government purposes from excluding people from an “otherwise open online dialogue” because they say things the official disagrees with, he wrote.

“This debate, as uncomfortable and as unpleasant as it frequently may be, is nonetheless a good thing,” Judge Parker wrote. “In resolving this appeal, we remind the litigants and the public that if the First Amendment means anything, it means that the best response to disfavored speech on matters of public concern is more speech, not less.”

The Justice Department had no immediate response to the ruling. But Jameel Jaffer, the director of the Knight First Amendment Institute at Columbia University, which represented a the group of Twitter users who were blocked by Mr. Trump and filed the lawsuit, praised it. He said that public officials’ social-media accounts are among the most significant forums for the public to discuss government policy.

“The ruling will ensure that people aren’t excluded from these forums simply because of their viewpoints and that public officials don’t transform these digital spaces into echo chambers,” Mr. Jaffer said. “It will help ensure the integrity and vitality of digital spaces that are increasingly important to our democracy.”

Donald Trump often uses his Twitter account, @realDonaldTrump, to make policy pronouncements and communicate with the public, driving the news of the day.

Against that backdrop, a group of Twitter users whom Mr. Trump had blocked from accessing his postings, asked the White House to be unblocked and then, when their request went unheeded, sued him.

The plaintiffs included Rebecca Buckwalter, a fellow at the liberal Center for American Progress. Her account was blocked after she responded to a tweet by Mr. Trump on June 6, 2017, in which he accused various mainstream news media outlets of being “fake news” media and said he would not have won the White House if he relied on them.

Ms. Buckwalter replied, “To be fair you didn’t win the WH: Russia won it for you” — and she was blocked by Mr. Trump’s account.

The lawsuit argued that Mr. Trump’s account amounted to a public forum — a “digital town hall” — so his decision to selectively block people from participating in that forum because he did not like what they said amounted to unconstitutional discrimination based on their viewpoints.

Mr. Trump’s legal team argued, among other things, that he operated the account merely in a personal capacity, and so had the right to block whomever he wanted for any reason — including because users annoyed him by criticizing or mocking him.

But the appeals court disagreed, saying he was clearly acting in a government capacity in his use of Twitter.

“We are not persuaded,” Judge Parker wrote. “We conclude that the evidence of the official nature of the account is overwhelming. We also conclude that once the president has chosen a platform and opened up its interactive space to millions of users and participants, he may not selectively exclude those whose views he disagrees with.”

The ruling upheld a May 2018 decision by a Federal District Court judge that also found Mr. Trump’s practice of blocking his critics from his Twitter account to be unconstitutional. After that ruling, the White House unblocked the specific plaintiffs’ accounts— but not other users who were not involved in the case — while filing an appeal.

This decision would apply (at least in the Second Circuit) to other elected officials who use their Twitter account to conduct government business. This decision can be cited as persuasive precedent by other courts.