The Knight First Amendment Institute at Columbia University and seven Twitter users have sued President Trump and his administration to stop him from blocking users on Twitter. The lawsuit, filed in New York Tuesday, alleges that the President’s behavior on Twitter infringes on free speech rights, and blocks users from accessing official government information.

The plaintiffs in this case include songwriter Holly Figueroa and comedian Nicholas Pappas, as well as a former professional cyclist, a police officer and a sociology professor. They all have been following Trump’s Twitter account, and in the past responded to his tweets with critical comments — only to find themselves blocked from accessing Trump’s tweets.

Twitter uses this type of blocking functionality as a safeguard against abusive comments — but the lawsuit alleges that Trump’s use of Twitter is a bit different from that of a normal user:

“Because of the way he uses the account, President Trump’s tweets have become an important source of news and information about the government, and the comment threads associated with the tweets have become important forums for speech by, to, and about the President.”

The lawsuit also refers to statements by Trump himself, as well as administration officials, that describe his use of Twitter as official communication. Blocking users from accessing these statements, it alleges, “violates the First Amendment because it imposes a viewpoint-based restriction on the Individual Plaintiffs’ ability to petition the government for redress of grievances.”

The Knight First Amendment Institute  is now asking the court to order the Trump administration to unblock the defendants, and prevent further such account blocking on Twitter. The White House didn’t immediately respond to a request for comment.