Critics blasted the law -- which includes a photo identification requirement -- as "regressive and discriminatory" and said it was aimed at suppressing minority turnout. They warned it could impact the presidential election in the state.
Republican supporters, including the governor, said it was needed to prevent possible voter fraud.
The ruilng by Federal District Court Judge Thomas D. Schroeder upheld a provision that ended same-day registration in the state and that requires voters show a photo ID card, such as a driver's license, to cast a ballot. The judge's opinion also trimmed the early-voting period by seven days and OK'd the repeal of a provision that allowed ballots cast outside a voter's home precinct to count.
In his opinion, Schroeder dismissed the claim that African-Americans, among others, would be harmed by the law, which was passed by the state legislature in 2013.
He ruled that "...minorities enjoy (an) equal and constitutionally compliant opportunity to participate in the electoral process" and that no evidence had been produced to show that African-Americans would be adversely impacted by the voting requirements.
North Carolina's Republican Gov. Pat McCrory, who signed the law, issued a statement
in support of the judge's opinion.
"This ruling further affirms that requiring a photo ID in order to vote is not only common-sense, it's constitutional," he said. "Common practices like boarding an airplane and purchasing Sudafed require photo ID and thankfully a federal court has ensured our citizens will have the same protection for their basic right to vote."
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The law's opponents, including the NAACP and the Advancement Project, a civil rights organization, said that they plan to appeal.
"Just like those who carried on before us, we will continue our movement challenging regressive and discriminatory voter suppression tactics on behalf of African-Americans, Latinos, seniors, students and all those for whom democracy has been denied," said Rev. William J. Barber II, president of the North Carolina NAACP, in a statement.
A lawyer for the NAACP told CNN that the voting requirements could impact the presidential election.
"If they stay in place, they would clearly have an impact on same-day registration, which is the parachute that North Carolina had," Daniel Donovan said. "You could register during early voting and vote."
Without same-day registration, he said, people who are not registered at least 45 days in advance won't be able to vote.
"Also, if you move from one county to another, you need to register again," Donovan added. "Those people will not be able to vote and that's skewed against minorities, because they move more than other voters."
If higher courts do not intervene, the changes in voting requirements will take effect this fall.
The ruling is the latest in response to the Supreme Court's 2013 decision to eliminate a portion of the Voting Rights Act that required nine states to have federal approval before changing their laws.
The Justice Department filed a lawsuit
in 2013 seeking to block parts of the North Carolina voting law.
Democrats had argued that the photo ID requirement didn't include protections for voters who don't have identification and that it would disproportionately affect minorities.