A group of Twitter users blocked by President Trump has filed a lawsuit against him, claiming the president blocking users on the social network is unconstitutional.

On Tuesday, seven individual defendants and the Knight First Amendment Institute at Columbia University filed suit against Trump, press secretary Sean Spicer and Dan Scavino -- the White House director of social media.

The suit argues that Twitter is a public forum under the First Amendment, and because the president's Twitter (@realDonaldTrump) is used for official government announcements, the tweets should be accessible to everyone. The suit asks the president to unblock the users.

"Twitter enables ordinary citizens to speak directly to public officials and to listen to and debate others about public issues, in much the same way they could if they were gathered on a sidewalk or in a public park, or at a city council meeting or town hall," the lawsuit said.

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If a place is considered a public forum -- like a park or a city hall -- people can't be excluded from attending because of their viewpoints. The lawsuit argues this applies to Twitter, too. The plaintiffs claim they were blocked by Trump after tweeting criticism.

Twitter did not have a comment on the lawsuit. The White House could not be reached for comment.

In a decision last month, Supreme Court Justice Anthony Kennedy said that "cyberspace," specifically social media, is the most important platform for exchanging views, citing Twitter as a place for petitioning elected officials.

The lawsuit against Trump and his aides, filed in the Southern District of New York, follows a letter sent by the Knight First Amendment Institute to the White House last month, asking the president to unblock people and claimed blocking critics was unconstitutional. The White House did not respond to the letter.

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The letter sparked debate over the constitutionality of elected officials blocking constituents. Some people argued that the account, @realDonaldTrump, was personal and therefore blocking people did not violate the constitution.

But the plaintiffs disagree.

For instance, Trump announced his decision for FBI director on Twitter, and has tweeted that his use of social media is "modern day presidential."

"If you look at how he and his aides have used his account since he became president, there are so many examples of him using it as the primary official account, and using it much more than @POTUS," Katie Fallow, senior staff attorney at the Knight Institute, told CNNTech.