RALEIGH, N.C. (AP) — Far-reaching voting changes in North Carolina approved by Republicans three years ago and upheld by a federal judge now head to an appeals court that previously sided with those challenging the law on racial grounds.

The 4th U.S. Circuit Court of Appeals scheduled oral arguments Tuesday, just two months after a lower court ruled photo identification requirements to vote in person, early-voting restrictions and other changes violated neither the federal Voting Rights Act nor the Constitution.

The appeals court’s decision to accelerate review of the case reinforces the stakes involved with the outcome in an election year, particularly in North Carolina. The presidential battleground state also has big races for governor and U.S. Senate on the fall ballot.

“The legislative actions at issue must be analyzed in the context of the high levels of racially polarized voting in North Carolina, where many elections are sensitive to even slight shifts in voting,” lawyers for the U.S. Justice Department wrote in a brief heading into the arguments before three judges in Richmond, Virginia.

The 2013 law being challenged by the department, state NAACP and other groups and voters required voters to show one of six qualifying IDs before casting a ballot. A change to the law last summer granted more exceptions to those unable to obtain an ID. The photo ID mandate began with the March 15 primary. Close to 20 states have photo ID mandates, including a Texas law that is now being examined by the full 5th Circuit.

The law also reduced early-voting by seven days, eliminated same-day registration during the early-voting period and barred the counting of Election Day ballots cast in the wrong precinct.

During two trials over the past year, those who sued said the changes were discriminatory because they disproportionately harmed black voters that use early voting and cast out-of-precinct ballots more than other voting groups. Their lawyers also said minority residents lacked photo ID more than others.

But U.S. District Judge Thomas Schroeder in Winston-Salem wrote in April the plaintiffs didn’t prove the laws made it harder for minority voters to cast ballots. Schroeder emphasized data showing higher voter registration and turnout rates among black residents in 2014, when many changes were implemented, compared to 2010.

Attorneys for the state and GOP Gov. Pat McCrory, who signed the challenged laws, say the appeals court should leave Schroeder’s 485-page decision alone.

The “plaintiffs have failed to cite a single case where a state has been guilty of purposeful discrimination because it enacted photo identification requirements or any of the current election practices implemented,” the lawyers wrote in their appeals brief. They pointed to testimony that 94 percent of all registered black voters had acceptable ID and more than 99 percent voted without casting an out-of-precinct ballot.

Still, that equates to thousands of people being disenfranchised, according to those challenging the law.

The plaintiffs stress a 2014 ruling in the case by a majority on a three-judge panel at the 4th Circuit that found two elements necessary for a vote-denial claim to be successful: the voting laws must impose a discriminatory burden on a protected class and must be caused or linked to social or historical conditions.

“On each of these scores, the case-critical evidence remains undisputed,” the plaintiffs’ attorneys wrote.

That divided panel ordered a preliminary injunction directing same-day registration and out-of-precinct voting continue while the case was pending. A majority on the U.S. Supreme Court soon disagreed and blocked that order for the November 2014 election. But subsequent court rulings have allowed same-day registration and out-of-precinct voting to resume.

It’s unclear whether the same three-judge panel will hear Tuesday’s arguments. Attorneys don’t know which judges will be seated until the morning of the hearing.