The Wisconsin Judicial Commission filed a complaint against Justice Michael Gableman on Tuesday, claiming he violated a rule that prohibits judicial candidates from knowingly misrepresenting facts about their opponents.

Gableman was the first challenger to defeat an incumbent justice in 41 years when he knocked off Louis Butler in the April election with 51 percent of the vote. Gableman, 42, joined the court for a 10-year term in August.

During the campaign, Gableman faced intense criticism from independent observers when his campaign ran a television ad that showed a picture of Butler, the state's first black justice, next to a mug shot of convicted rapist Reuben Lee Mitchell, who is black. A narrator said: "Butler found a loophole. Mitchell went on to molest another child."

When Butler was a public defender, he represented Mitchell on the appeal of his 1985 conviction for raping an 11-year-old girl.

Butler convinced an appeals court that Mitchell deserved a new trial because certain evidence should not have been allowed. The Supreme Court overturned that decision and Mitchell served his full sentence. After his release on parole in 1992, Mitchell was convicted of raping a 14-year-old girl and sentenced to 40 years in prison.