In the prolonged legal battle over a North Carolina Supreme Court seat, a state appeals court panel ruled on Friday that tens of thousands of voters must promptly verify their eligibility or have their ballots thrown out. The decision could lead to the results of the November election being overturned.

The ruling was a win for Judge Jefferson Griffin, a Republican who narrowly lost the election in November and challenged the result. His opponent, Justice Allison Riggs, is one of two Democrats on the seven-member Supreme Court. The case has tested the boundaries of post-election litigation and drawn wide criticism.

Judge Griffin’s legal argument centers on a claim that about 65,000 people who cast their ballots in the election were ineligible to vote, mostly because they did not provide proof of identity — either the last four digits of a Social Security number or a driver’s license number — when they registered.

There is evidence in court filings, however, that many of those voters did provide that information, but for several reasons — name changes after marriage, key-punching mistakes — they never appeared in the database.

Although the omissions were no fault of the voters, Judge Griffin has argued, they left the voters’ eligibility in question. He has said that their ballots should be thrown out unless they provide legitimate proof of identity within a limited period of time set by the state.

Two Republican judges on the North Carolina Court of Appeals, John Tyson and Fred Gore, agreed with Judge Griffin in the majority opinion for the three-judge panel, arguing that even one unlawful vote essentially “disenfranchises lawful voters.” They ruled that the voters in question “should be allowed a period of 15 business days after notice to cure their defective registrations.”