Three Alabama citizens are suing state Secretary of State John Merrill for blocking them on Twitter.

The three registered voters claim in a complaint filed on their behalf Wednesday by the American Civil Liberties Union of Alabama that Merrill violated their First Amendment rights by blocking them from interacting with his official @JohnHMerrill account on the popular social media site.

Brock Boone, an attorney with the ACLU of Alabama, described the move by Merrill as a "violation of the First Amendment" that amounts to a decision to "discriminate against" his own constituents.

"When a government official intentionally opens up a public conversation, that official can't block individuals from joining the conversation because of the views that are expressed" Brock Boone, an attorney with the ACLU of Alabama, told AL.com via email Tuesday.

Merrill spoke with AL.com Wednesday morning about the lawsuit, which he called "a political hack job" and said he had not previously heard about.

"I hope what you'll do is what I've asked you to do in the past and that's to put my cellphone number in the paper: 334-328-2787. Because anyone in the state that wants to get in touch with me, can call me on my cellphone," he said.

"This is the bottom line: anyone who wants to get in touch with me in this state can do so, but they don't get to choose how they get in touch with me."

The question of whether public officials have a right to block their constituents has emerged as a national issue in recent months. In May, the topic garnered national headlines when a federal judge ruled that President Donald Trump cannot block Twitter users. The ruling came in response to a July 2017 lawsuit filed by Columbia University's Knight First Amendment Institute and seven Americans who Trump had blocked on Twitter.

The Montgomery Advertiser reported in June that Merrill addressed the topic of his blocking Twitter users following the federal court ruling regarding Trump's Twitter feed.

"I'm not unblocking anybody I've already blocked, because there's a reason those people were blocked. Anyone else that I feel needs to be blocked in the future will also be blocked," Merrill said at the time, according to the Advertiser.

The three plaintiffs in the ACLU's new case before the U.S. District Court of Alabama's Middle District claim that Merrill violated their First Amendment rights when he blocked them on Twitter. Kimberly Fasking, a student at Samford University's Cumberland School of Law, says Merrill blocked her after she tweeted a question about crossover voting; Alabama resident Heather Melvin Boothe claims in the complaint she was "blocked for stating 'Good point! Ballot has major typo'"; and Alabama farmer and educator Herbert Hicks says he "was blocked after asking Merrill about a speaking engagement."

According to the complaint, Merrill blocking the Twitter users "imposes an unconstitutional restriction on their participation in a designated public forum. It imposes an unconstitutional restriction on their right to access statements that Defendants are otherwise making available to the public at large. It imposes an unconstitutional restriction on their right to petition the government for redress of grievances."

Merrill rejects that argument and blames the controversy on partisan politics.

"Its not worth the ACLU's time, it's a political hack job and they're trying to build support for the democratic nominee for secretary of state," he said Wednesday.

Fasking said that she was "disappointed" by Merrill's decision to block her.

"It is upsetting to me that the Secretary of State, who primarily uses his Twitter account to disseminate information on issues related to his office, has also weaponized that account by blocking those with whom he disagrees politically," Fasking said in an ACLU statement. "It is not the Secretary of State's job to communicate only with those who agree with him, but with all of the people of the State of Alabama."

Steven Gregory, an attorney for the plaintiffs, seconded those concerns.

"The First Amendment protects everyone's right to participate in political speech without regard to political viewpoint," Gregory said in the ACLU statement. "The Alabama Secretary of State should engage in protecting that right on his Twitter account, not suppressing it by blocking inoffensive content."