WASHINGTON — The Supreme Court on Monday turned away a challenge to a Wisconsin law that requires prospective voters to provide photo identification before casting their ballots.

Officials in Wisconsin said they would not enforce the law in the next election, on April 7, but would require compliance in later ones. The April election includes contests for judicial seats and local offices.

“Absentee ballots are already in the hands of voters, therefore, the law cannot be implemented for the April 7 election,” Attorney General Brad Schimel said in a statement. “The voter ID law will be in place for future elections — this decision is final.”

Dale Ho, director of the American Civil Liberties Union’s Voting Rights Project, said the group would continue to fight. “We’re pleased the state has agreed with the A.C.L.U.’s position that imposing a new restriction on voters in the midst of an election is a recipe for disaster,” he said in a statement. “For now, the voters of Wisconsin will be able to cast their ballots free from the burdens placed on them by this law. But this should be the case for voters permanently, not just for one election.”

The Supreme Court’s decision not to hear the case was a surprise, as the court last year temporarily blocked the law for the November election, and voters were not required to show photo identifications in order to vote.

The Wisconsin law, one of the strictest in the nation, was enacted in 2011 but had been mostly blocked by various courts. It requires prospective voters to show a current or recently expired Wisconsin driver’s license or a similar identification issued to people who do not drive, a military ID, a United States passport, a tribal ID, a recent naturalization certificate or some Wisconsin student IDs.

The state said the law was needed to combat voter fraud. But cases of impersonation at the polls are very rare.

On the other hand, a federal trial judge wrote, the Wisconsin law would “deter or prevent a substantial number of the 300,000-plus registered voters who lack ID from voting” and would disproportionately affect black and Hispanic voters.

A three-judge panel of the United States Court of Appeals for the Seventh Circuit, in Chicago, upheld the law, reasoning that it was similar to one from Indiana that the Supreme Court had sustained in 2008 in Crawford v. Marion County Election Board.

The full Seventh Circuit deadlocked 5 to 5 on a request to rehear the Wisconsin case, drawing a sharp dissent from Judge Richard A. Posner, who had written the 2007 appeals court opinion upholding the Indiana law, later affirmed by the Supreme Court.

Civil rights groups had hoped the Supreme Court would use the Wisconsin case, Frank v. Walker, No. 14-803, to reconsider its 2008 decision. There are other voter ID cases in the pipeline, notably one from Texas, and the Supreme Court may return to the subject in one of those.

In a second development on Monday, the Supreme Court agreed to decide whether its 2012 decision barring mandatory life-without-parole sentences for juvenile killers must be applied retroactively.

The court had been poised to decide the question in a different case, one involving George Toca, a Louisiana man who was 17 in 1984 when, according to witnesses, he fatally shot a friend during an armed robbery.

But in February the court dismissed the case, Toca v. Louisiana, No. 14-6381, after Mr. Toca was released from prison as part of a plea agreement.

The new case, Montgomery v. Louisiana, No. 14-280, concerns Henry Montgomery, who was 17 in 1963 when he murdered an East Baton Rouge police officer.

In the 2012 decision, Miller v. Alabama, the Supreme Court ruled that such mandatory life sentences for juvenile offenders violated the Eighth Amendment‘s ban on cruel and unusual punishment. Life-without-parole sentences remained permissible, the court said, but only after individualized consideration.

The decision followed two others concerning harsh penalties imposed on juvenile offenders. In 2005 in Roper v. Simmons, the court eliminated the juvenile death penalty. In 2010 in Graham v. Florida, the court ruled that sentencing juvenile offenders to life without the possibility of parole was also unconstitutional, but only for crimes that did not involve killings.