On Thursday, Tennessee Gov. Bill Lee, a Republican, signed a law requiring groups that pay employees and hold voter registration drives to adhere to a strict list of requirements, or face civil fines or criminal punishment.

“We want to provide for fair, for genuine, for elections with integrity, and that’s why I signed the bill,” Lee said.

Hours later, civil rights groups announced they’d filed a lawsuit challenging the new law.

The lawsuit, filed by the Lawyers’ Committee for Civil Rights Under Law, the NAACP, and other groups, argues that the Tennessee law will “violate the due process clause of the Fourteenth Amendment and have a chilling effect on the exercise of fundamental First Amendment rights.” The new voter registration law “places onerous, unnecessary, burdensome, and unconstitutional obstacles upon on people who want to help others register to vote,” the lawsuit argues.

Voting rights groups in the state protested the measure for weeks before it passed, arguing that it punishes groups for trying to increase the number of voters in the state. They say they are being punished for their success in the 2018 midterm cycle, which saw a historic surge in voter turnout that helped deliver wins to a number of Democratic politicians across the country.

A group of protesters are outside the @TNHouseReps today in opposition to a bill from @SecTreHargett that would penalize groups that turn in more than 100 incomplete voter registration forms. This is the largest group of protesters at the Tennessee Capitol this year pic.twitter.com/S0E6piLMcG — Joel Ebert (@joelebert29) April 15, 2019

“Tennessee’s law is one of the most restrictive voter suppression measures that we have seen this year,” Kristen Clarke, president and executive director of the Lawyers’ Committee for Civil Rights Under Law, said in a Thursday statement announcing the lawsuit. “This is nothing more than a thinly veiled attempt to discourage and deter people from helping others to register to vote.”

The law specifically targets groups that pay people to help register voters

The new law, which was publicly endorsed by Tennessee Secretary of State Tre Hargett, fines voter registration groups who “knowingly or intentionally” submit incomplete or inaccurate registration forms.

The penalties are based on the number of “deficient” voter registration forms they submit; groups submitting more than 500 incomplete forms could be fined as much as $10,000, while those submitting 100 incomplete forms could be fined as much as $2,000.

According to the Associated Press, the law also makes it a Class A misdemeanor — punishable by a maximum $2,500 fine and/or jail time — for registration drive organizers to miss training sessions led by state officials, or for groups to pay a person for every registration form they collect. The measure also requires organizations to mail in collected voter registrations within a 10-day window or face additional penalties.

The legislation came months after one coalition, the Tennessee Black Voter Project, worked to register close to 90,000 voters before the midterm elections. Last year, the Tennessee Black Voter Project and the Memphis NAACP sued Shelby County, Tennessee, arguing that election officials failed to give potential voters time to correct issues on their registrations. The county was later ordered to allow the applicants to fix their registration forms.

As a result, the measure was sharply criticized by voting rights groups and activists in the state, who argued that the measure was clearly a punishment for the surge in voter registrations among black communities.

State officials countered that the measure was necessary after the incomplete forms were submitted last year, forcing officials to rush to review them all before the registration deadline. Hargett has said that it cost $200,000 to deal with the incomplete Shelby County forms.

But activists who worked with the Tennessee Black Voter Project said that the incomplete forms were submitted only because of a state requirement that groups submit all voter registrations, including ones they know are incomplete. They add that a law penalizing groups for the mistakes on forms is a clear attack on efforts to mobilize black voters.

“Black-led, community-based organizations throughout Tennessee have been registering more voters, turning them out to vote and winning more elections for progressive issues and candidates,” Cliff Albright, a founder of the Black Voters Matter Fund, recently wrote in a New York Times op-ed. “The fact that racial progress here has resulted in a white backlash is consistent with Tennessee history.”

“Aside from having its priorities badly misplaced, the state’s actions conflict with some of our nation’s most fundamental ideals and, we believe, violate the U.S. Constitution,” Bradford Berry, general counsel of the NAACP, said in a statement. “The NAACP is committed to having this badly flawed legislation overturned by the courts.”

Tennessee is not the only state to consider creating new penalties for voter registration-related errors. In Texas, legislators are considering a law that voting rights advocates believe will punish people for errors on their voter registration forms or for voting without knowing they are ineligible.

That proposal has also been strongly condemned by activists and civil rights groups, who argue that the proposal is unnecessary and could hamper efforts to mobilize some voters.