The following editorial appeared in Wednesday's Washington Post:

Kris Kobach, the Republican secretary of state in Kansas, for years has been warning that voter fraud is so rampant that restrictive laws are needed to prevent noncitizens from voting. A legal challenge to the Kansas law he championed requiring voters to show proof of citizenship was his opportunity to back up his claims. Not only did he fail to produce any credible evidence whatsoever, but he also ended up being sanctioned by a federal judge. The decision is a rebuke to Kobach and others who, like him, traffic in xenophobia and lies about voter fraud.

A ruling issued Monday by U.S. District Judge Julie Robinson struck down a Kansas law that went into effect in 2013 that required voters to produce proof of citizenship, such as a passport or birth certificate, to register to vote. The American Civil Liberties Union filed suit on behalf of the League of Women Voters and individual Kansans. Instead of combating voter fraud, the judge found the law had disenfranchised tens of thousands of eligible voters, violating the 1993 National Voter Registration Act and the 14th Amendment.

As to Kobach's argument during trial that the relatively small number of noncitizens who had tried to vote represented only "the tip of the iceberg," the judge wrote, "there is no iceberg; only an icicle, largely created by confusion and administrative error." The ruling is in keeping with the long-standing and widespread agreement from election experts that voter fraud is extremely rare.

The Kansas law was uniquely harsh in requiring documented proof of citizenship, but the ruling should serve as a warning to other states that try to erect barriers to voting. The ruling's discrediting of Kobach is significant because of the national name he has made for himself as chief purveyor of voter-fraud claims and anti-immigration rhetoric. An ally of President Donald Trump who served as vice chairman of the short-lived Presidential Advisory Commission on Election Integrity, Kobach now hopes to be governor in Kansas, running for the GOP nomination in an August primary.

Voters would do well to pay attention to the part of the 118-page ruling that deals with Kobach's conduct as both defendant and lawyer during the trial earlier this year. So wanting was his representation — violating rules "designed to prevent prejudice and surprise" — that the judge ordered him to complete six hours of legal education. Kobach said he plans to appeal the ruling. He would do better to go to class.