Can Donald Trump block you? A First Amendment group is suing to find out.

It is where he inveighs against “FAKE NEWS,” promotes his television appearances, and trumpets his administration’s accomplishments. It’s also where he reports on meetings with world leaders, discusses policy positions, and announced his choice for FBI Director. President Donald Trump’s Twitter feed is the epicenter of a new-age White House communications strategy that has earned the oft-repeated label “unprecedented.”

Whether Trump’s demeanor in the messages he posts is “presidential” is debatable, but his own spokespeople have made clear that his tweets constitute “official statements.” Not everyone, however, can see those statements or participate in the discussion that occurs in the replies.

On Tuesday, the Knight First Amendment Institute at Columbia University filed a lawsuit against Trump and two of his top advisors on behalf of seven people who have been blocked from viewing tweets by the president’s @realDonaldTrump account. Attorneys at the Knight Institute argue that Trump’s blocking of users who have criticized him amounts to viewpoint-based exclusion, which is not allowed under the First Amendment.

“President Trump’s Twitter account, @realDonaldTrump, has become an important source of news and information about the government, and an important public forum for speech by, to, and about the President. In an effort to suppress dissent in this forum, Defendants have excluded—‘blocked’—Twitter users who have criticized the President or his policies. This practice is unconstitutional,” the federal suit alleges.

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The case raises complicated questions about how to apply constitutional principles written in a time of pamphlets and town square debates to the realities of the Facebook and Twitter era. Skeptics might say that blocking someone on Twitter doesn’t make it impossible for that person to see tweets. He or she can simply sign out of that account or create a different one. Blocking adds a barrier to entry, to be sure, but it’s not an insurmountable obstacle. Additionally, as anyone who spends time on Twitter knows, comments on the platform can be crude, distasteful, and even scary, and blocking trolls allows for some measure of control over the people with whom you interact.

But attorneys at the Knight Institute have put forward a series of arguments that make a compelling case for thinking differently. They are not arguing that we redefine Twitter—a privately owned social media platform—writ large as a virtual town square where all voices are welcome. Rather, they claim that “because of the way the President and his aides use the @realDonaldTrump Twitter account, the account is a public forum under the First Amendment.”

If the president’s feed is defined as a “public forum,” citizens cannot be excluded from viewing his statements and engaging in discussions simply because they disagree. The lawsuit alleges that Trump, along with Press Secretary Sean Spicer and Social Media Director Dan Scavino, have violated the First Amendment rights of seven Americans who were blocked soon after criticizing or mocking the president, and that the block infringes on the plaintiffs’ “First Amendment right to petition their government for redress of grievances.”

“When [government officials] open up a space and allow the general public to come in and comment in that space, whether a city council meeting or a Facebook page, that is a ‘designated public forum,’” Katie Fallow, a senior attorney at the Knight Institute, tells CJR. “The courts have held that when you do that, you can’t then exclude people based on viewpoint.” The Knight Institute, which has not been blocked by Trump’s account, is also a plaintiff in the suit. It argues that users who aren’t blocked are being “deprived of their right to read the speech of the dissenters.”

The reaction from legal experts last month to the Knight Institute’s letter declaring its intent to sue was mixed, with some supporting the effort and others arguing the plaintiffs had a tough legal hill to climb. But in the weeks since, the Supreme Court issued a decision in which Justice Anthony Kennedy described social media as “the modern public square.

Trump recently referred to his use of social media as “modern day presidential.” It will now be left to the courts to decide whether that requires a modern day update to First Amendment protections.

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Pete Vernon is a former CJR staff writer. Follow him on Twitter @ByPeteVernon.

TOP IMAGE: Official DHS photo by Jetta Disco.