In 2008 the majority-black town of Kinston in eastern North Carolina voted almost 2-to-1 to make its local elections nonpartisan. Nine months later, as the measure was set to kick in, the Justice Department blocked it.

The department’s reason: The plan would reduce the power of black voters.

The dispute in the town of 22,000 spawned a lawsuit that is now before the Supreme Court as a potential test case for the 1965 Voting Rights Act. The landmark law was enacted to combat the discrimination that had kept blacks away from Southern polling booths for generations and has been used in this year’s elections to challenge Republican-backed voter-identification laws.

The suit takes aim at one of the 1965 law’s core provisions: the power it gives the federal government to block changes in local election rules, like the one in Kinston, in 16 states.

“The people wanted it, and we got one bureaucrat in D.C. that says, ‘No, you can’t have it,’ ” Kinston Mayor B.J. Murphy, R, who is white, said over the clinking of coffee cups at Christopher’s cafe on Queen Street, the town’s main road and unofficial dividing line separating its mostly black east side from its largely white west side.

The Justice Department has since taken the unusual step of withdrawing its objection, clearing the way for nonpartisan elections this year while complicating the legal case.

But the Washington-based Center for Individual Rights, which works to limit governmental power, is pressing ahead with its suit against the department and asking the high court to invalidate part of the Voting Rights Act.

The court may decide next month whether to take up the Kinston case or a similar one from Shelby County, Ala. The cases are separate from the legal fights over voter-ID laws, which have drawn most of the public’s attention, and wouldn’t be decided until after the November election.

Even so, the Voting Rights Act challenges may have greater long-term significance, potentially undercutting federal power to block such measures in the future and wiping out a pillar of U.S. election law.

Kinston is at once integrated and racially divided. Even as blacks and whites greet one another cheerfully in Christopher’s and the Queen Street Deli, they tend to head in different directions afterward. While the richer west side of town is multiracial, the poorer east side is almost entirely black. Kinston High School is 91 percent minority.

The city has long been Democratic-controlled. Until Murphy’s election in 2009, no Republican had won either the mayor’s office or a seat on the city council since at least Reconstruction.

In 2008, a group of Republicans sought to break the Democratic stranglehold. Activists gathered enough signatures to put an initiative on the ballot to eliminate party primaries and the straight-ticket option for general elections. Mayoral and council candidates instead would run in a single, nonpartisan election.

The initiative won 64 percent approval, with voters in five of the town’s seven majority-black precincts backing it. Tyson says the black support stemmed from the way the proposal was packaged.

“It was presented to them as, ‘If you go nonpartisan, the city is 62 percent black, you should be able to win most if not all of the seats,’ ” he said. At the time of the vote Kinston residents had never elected a majority-black city council.

The city was poised to use the nonpartisan system in 2009 – joining the vast majority of North Carolina cities – when the Justice Department denied preclearance, blocking the change.

In an August 2009 letter, acting Assistant Attorney General Loretta King said the new rules would cause black candidates to lose a “small but critical” source of support: white voters driven by party loyalty to support any Democrat, regardless of race.

King said those white voters were crucial even though blacks constituted 64.6 percent of the city’s 14,799 registered voters. She said blacks comprised a minority of the electorate in three of the four most recent general elections.

The move prompted a lawsuit by Nix and other Kinston Republicans.

“It was an extraordinary act of the Justice Department to tell a two-thirds-black majority town that it could not shift to the same form of local government election that is overwhelmingly used throughout the state of North Carolina,” said Richard Pildes, an election-law expert who teaches at the New York University School of Law.

Two and a half years later, the Justice Department withdrew the objection. In a February 2012 letter, Assistant Attorney General Thomas Perez pointed to “a shift in the electoral patterns in Kinston elections,” including the 2011 vote that for the first time produced a majority-black city council.

Perez also cited Kinston’s rising black population, though the black share of registered voters had increased less than 1 percentage point, to 65.4 percent. The department’s shift cleared the city to hold its first nonpartisan election this November.

The move also may have undermined the legal case. A federal appeals court in Washington threw out the lawsuit as moot, saying the challengers had “obtained everything that they could recover from this lawsuit.”