MINNEAPOLIS — A federal appeals court will hear oral arguments Tuesday on whether Minnesota’s program that keeps sex offenders confined indefinitely after they complete their prison sentences is unconstitutional and needs to be reformed.

U.S. District Judge Donovan Frank declared the treatment program unconstitutional last year, citing how rarely anyone gets released from it. He didn’t shut it down, but ordered changes including risk assessments of all the more than 700 civilly committed offenders in the program to determine who should be put on a pathway for release.

The 8th U.S. Circuit Court of Appeals in December put Frank’s order on hold so a three-judge panel could hear the state’s appeal in the long-running legal fight. No immediate ruling is expected after the Tuesday hearing in St. Louis.

Only a handful of offenders have been provisionally released to community-based settings in the Minnesota Sex Offender Program’s 20-plus-year history, which is why the plaintiffs in the class-action lawsuit say it’s tantamount to a life sentence. While civilly committed offenders in California, Wisconsin, New Jersey and other states are allowed to re-enter society after completing treatment, no one has been fully discharged from Minnesota’s program.

Lawyers for the offenders wrote in their brief that the case arose because of “years of inaction” by the state despite repeated warnings by outside experts that program was “broken, unsustainable and likely unconstitutional.” They said the district court correctly found that the program lacks the necessary safeguards and that it fails to provide less-restrictive alternative treatment settings to the program’s prison-like facilities in St. Peter and Moose Lake.