ST. LOUIS — The lengthy legal debate over a Minnesota program that keeps sex offenders confined indefinitely after they complete their prison sentences shifted south Tuesday as state officials urged a federal appeals court nearly 500 miles away to overturn a judge’s ruling that the program is unconstitutional.

Solicitor General Alan Gilbert told a three-judge panel of the 8th U.S. Circuit Court of Appeals in St. Louis that District Judge Donovan Frank “lost his neutrality” when he made critical comments before ruling last summer. Even before his ruling, the judge called the program “draconian” and said it is “clearly broken” and needs to be reformed.

“He has prejudged the program,” said Gilbert, who asked the jurists to reverse the lower court ruling and appoint a new judge to consider the suit by 14 plaintiffs on behalf of the more than 700 civilly committed offenders. The panel did not immediately issue a decision after hearing 20-minute presentations by both sides.