A prominent civil rights group filed a lawsuit against multiple election boards in North Carolina on Monday, alleging that they are deliberately and illegally suppressing black votes, Think Progress reports.

The lawsuit filed by the North Carolina NAACP claims that the cancelation of 4,500 voter registrations in three North Carolina counties — Beaufort, Moore, and Cumberland — violates the National Voting Registration Act (NVRA).

The lawsuit claims these registrations were purged due to a single piece of mail sent to voters and returned as undeliverable, according to Think Progress.

Some voters impacted by the mailing moved to different addresses within the same county, while others still reside at the addresses listed on their registrations. These voters are disproportionately black, the NAACP claims.

The Huffington Post lays out why this method of purging voters prompted a lawsuit.

"Under the NVRA, states may cancel registrations only if a voter provides written notice of a change in address or if a voter does not respond to a notice for two election cycles and fails to vote for two federal election cycles. The act also bars states from removing voters from the rolls 90 days or less before a federal election."

The lawsuit further argues that the state canceled voter registrations in a "coordinated effort" with the North Carolina GOP.

“We are seeing the worst attempts of voter suppression here in North Carolina that we’ve seen since the days of Jim Crow,” North Carolina NAACP president Rev. Dr. William Barber told reporters at a Monday press conference. “The Tar Heel state is ground zero in the intentional, surgical efforts to suppress the voice of voters. These attempts are a direct affront to our Constitution.”

The lawsuit aims to restore the canceled registrations and crack down on further efforts to suppress black votes, Time reports.

The lawsuit reveals a clash between the NVRA and how election challenges are conducted in North Carolina.

When a voter's registration is challenged in North Carolina, county BOEs hold a preliminary hearing, the complaint explains (PDF). At this hearing, the state determines whether the challenge is valid and considers a single returned first-class letter "prima facie evidence that the person no longer resides in the precinct." If the hearing determines that the challenge is valid, the voter is notified to appear at a second hearing to present evidence that they reside where they are registered to vote. If they fail to appear, their registration is canceled.

The NAACP alleges that North Carolina's process violates the NRVA, which only allows states to cancel a voter's registration if they do not respond to notices for two election cycles.

Kim Westbrook Strach, executive director of the N.C. State Board of Elections, disagrees with that assessment. 

“These voter challenges were filed by private citizens, not elections officials," told ATTN: in a statement via email. "Our independent agency administers state and federal election laws. The statutes at issue are decades old and are common across the country and widely regarded as compatible with the National Voter Registration Act (NVRA). If the plaintiffs are right, then most states are wrong.”

This is not the first time North Carolina's election practices have clashed with federal laws.

As ATTN: has reported previously, a North Carolina voter ID law was struck down in July. The federal court decision asserted that the state's voter ID laws “target African Americans with almost surgical precision.”

On Thursday, U.S. District Judge Loretta Biggs determined that a North Carolina voter registration practice that omitted voters registered at a DMV violated the NVRA. Biggs ordered North Carolina elections officials to grant provisional ballots to voters impacted by the DMV omissions, WRAL reports.