AUSTIN, Texas (AP) — Nine Texans have sued state Attorney General Ken Paxton, claiming he blocked them on Twitter for criticizing him or his policies in comments responding to his tweets.

The lawsuit, filed Thursday in federal court in Austin, asks a judge to declare Paxton’s action unconstitutional and require him to unblock the plaintiffs and anyone else he has blocked because of their viewpoints.

The suit is the latest legal challenge to public officials who block constituents on social media, according to The Dallas Morning News.

“Attorney General Paxton is preventing Texans from exercising their First Amendment rights. He cannot bar them from directly expressing their criticisms of his policies and qualifications by blocking them on Twitter,” said Kate Huddleston, attorney for the ACLU of Texas, who is representing the plaintiffs.

The Knight First Amendment Institute at Columbia University, which filed a similar lawsuit against then-President Donald Trump, has also joined the suit.

The nine plaintiffs in the Paxton suit include a U.S. Army veteran, an immigration advocate, the leader of a progressive political group, two students, a lawyer and a journalist.

The court will decide whether Paxton’s Twitter account, @KenPaxtonTX, is a personal or official account. Some politicians, including Trump, have tried to claim their accounts are personal and not official methods of communication to evade First Amendment violations.

In addition to this lawsuit, the FBI is reportedly investigating claims of abuse of power in a whistleblower lawsuit by former employees who say Paxton fired them after they accused him of abusing his power to help a campaign donor.

Twitter also filed a lawsuit against Paxton, claiming he abused his authority to “intimidate, harass and target Twitter in retaliation” for the company’s internal decision making processes for banning users.

Paxton did not respond to the Dallas News’ request for comment.