WASHINGTON (AP) — The Supreme Court on Monday rejected an appeal from Kansas that sought to revive a law requiring proof of citizenship to register to vote. A federal appeals court had declared the law unconstitutional.

Kansas had been the only state to require people to show a physical document such as a birth certificate or passport when applying to register to vote. The issue is distinct from state laws that call for people to produce driver licenses or other photo IDs to cast a vote in person.

The law was championed by former Kansas Secretary of State Kris Kobach, who led President Donald Trump’s voter fraud commission. Kobach was a leading source for Trump’s unsubstantiated claim that millions of immigrants living in the U.S. illegally may have voted in the 2016 election.

Roughly 30,000 people were prevented from registering to vote during the three years the law was in effect, and the state’s own expert estimated that almost all of those were U.S. citizens who were eligible to vote.

Dale Ho, director of the American Civil Liberties Union’s Voting Rights Project who argued the case, said the Supreme Court’s decision not to review the case will “finally close this chapter on Kris Kobach’s sorry legacy of voter suppression.”

Kansas Secretary of State Scott Schwab, who supported the law when he was in the state Legislature, pursued the Supreme Court appeal over the objection of Kansas Gov. Laura Kelly.

The 10th U.S. Circuit Court of Appeals declared the law unconstitutional in April, affirming a trial court ruling. Justice Neil Gorsuch, who used to be a 10th Circuit judge, sat out the Supreme Court’s consideration of the case.

Schwab said Monday he was hoping for some guidance from the nation’s highest court on how far the state can go in imposing a proof-of-citizenship requirement and suggested it would take another lawsuit to get it.

But he downplayed the ruling’s practical effect on the administration of elections in Kansas.

“We don’t have massive voter fraud in the state of Kansas. I think we found that out during this election,” he told reporters after a meeting of the state’s presidential electors at the Statehouse.” As it relates to the outcome, the way we do elections going forward, it’s not going to change a lot, but it does limit what states can do.”