The Supreme Court declined Monday to revive a Kansas law that required showing specific proof-of-citizenship documents before registering to vote, ending a fight that had continued for years.

A trial court and the U.S. Court of Appeals for the 10th Circuit had declared it unconstitutional. It was championed by former Kansas secretary of state Kris Kobach, a Republican who had led the short-lived voter fraud commission President Trump formed to try to substantiate his unproven claims that millions of immigrants living illegally in the United States were voting.

Kobach was defeated in his attempts for higher office in the state.

The court did not give a reason for rejecting the appeal of the state’s new secretary of state, Scott Schwab. Kansas Gov. Laura Kelly (D) had opposed the effort asking for Supreme Court review.

Kansas had been the only state to require a physical document such as a birth certificate or passport to register to vote. The state said it did not deter legitimate voters because it allowed additional kinds of identification forms.

But courts said the requirements did not conform with a federal voting law and the Constitution.

The American Civil Liberties Union, which led the fight against the law, said it disallowed about 30,000 people who were qualified to vote before the courts struck it down.

“This case concerns only an idiosyncratic requirement in a single state: Kansas’s particular method for requiring first-time registrants to prove they are citizens — by presenting a document establishing U.S. citizenship,” the organization said in opposing Kansas’s request to hear the case.

It is not like a voter-ID law, which usually requires voters at the polls to show ID such as a driver’s license. “People almost never carry” the kinds of documents Kansas required, the brief said, “and often do not have or cannot easily locate them.”

“Tens of thousands of Kansas voters were illegally denied the most fundamental right in our democracy because of this law,” Dale Ho, director of the ACLU’s Voting Rights Project, said in a statement.

Justice Neil M. Gorsuch, who previously served on the 10th Circuit, said he did not participate in the court’s deliberations.