SALT LAKE CITY — A federal appeals court will hear arguments Monday over the constitutionality of a struck-down Kansas statute that had required people to provide documents proving their U.S. citizenship before they could register to vote.

In a case with national implications for voting rights, Kansas faces an uphill battle to resurrect the law once championed by former Kansas Secretary of State Kris Kobach, who led President Donald Trump's now-defunct voter fraud commission.

A three-judge panel of the 10th Circuit Court of Appeals temporarily blocked Kobach in 2016 from fully enforcing the law, calling it "a mass denial of a fundamental constitutional right." The issue is back before the appellate court after U.S. District Judge Julie Robinson struck it down last year and made permanent the earlier injunction.

"Kansas was the tip of the spear of an effort to make it harder for people to register under the guise of protecting elections from a nonexistent epidemic of noncitizen voting. Those efforts haven't stopped as this case illustrates, and I think this case will be closely watched," said Dale Ho, director of the American Civil Liberties Union's Voting Rights Project.

The legal fight has drawn national attention as Republicans pursue voter ID laws they say are aimed at people who are unlawfully in the country. Critics contend such efforts amount to voter suppression that target Democratic-leaning minorities and college students who may not have such documentation.

Kobach, a conservative Republican, 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.

Kansas Attorney General Derek Schmidt said in an emailed statement that the statute was enacted by large bipartisan majorities in the Legislature.

"The Legislature is free to repeal the statute if it is no longer favored, but as long as the law requiring documentary proof of citizenship to register to vote remains on the books, we think it, like other duly enacted state laws, deserves a full and vigorous legal defense," Schmidt said.

Kansas argued in court filings that it has a compelling interest in preventing voter fraud. It contended its proof-of-citizenship requirement is not a significant burden and protects the integrity of elections and the accuracy of voter rolls.

Critics countered that the documentary proof-of-citizenship law was "a disastrous experiment" that damaged the state's voter rolls, disenfranchised tens of thousands and eroded confidence in the state's elections.

The National Conference of State Legislatures has counted 35 states that have laws requiring some form of identification at the polls, but the Kansas voter registration statute at issue goes further by requiring people to provide documents such as a birth certificate, U.S. passport or naturalization papers before they can even register to vote. Arizona is the only other state with a similar law in effect, but it is far more lenient and allows people to satisfy it by writing their driver's license number on the voter registration form. Proof-of-citizenship laws in Alabama and Georgia are not currently being enforced.

Judge Robinson found that between 1999 and 2013 a total of 39 noncitizens living in Kansas successfully registered, mostly due to applicant confusion or administrative error. That is .002 percent of the more than 1.76 million registered voters in Kansas as of Jan. 1, 2013. Eleven of those 39 noncitizens voted.

The registration law took effect in January 2013. In the three years before the appellate court put it on hold, more than 30,732 Kansans were not allowed to register to vote because they did not submit proof of citizenship. That figure represented about 12 percent of voter registration applications.