A federal appeals court in St. Louis has declared that Minnesota's sex offender treatment program is constitutional — handing a major victory to the state but potentially derailing long-awaited reforms to its system of indefinite detention for sex offenders, reports the Star Tribune.

In a decision released Tuesday, a three-judge panel of the Eighth Circuit Court of Appeals reversed a lower-court ruling and found that Minnesota's system of committing sex offenders beyond their prison terms serves a "legitimate interest" in protecting citizens from dangerous sexual predators.

A class of sex offenders sued the state in 2011, arguing during a prolonged trial that Minnesota's system violated their due-process rights under the U.S. Constitution by depriving them of access to the courts and other basic safeguards found in the criminal justice system.

But after reviewing the program and state law, the appeals court sided with the state, concluding that Minnesota provided adequate constitutional protections, including the right to petition for release.

"We conclude that the class plaintiffs have failed to demonstrate that any of the … arguable shortcomings in the MSOP were egregious, malicious, or sadistic as is necessary to meet the conscience-shocking standard," the Eighth Circuit panel ruled.

The plaintiffs' lead attorney said the appellate judges used too narrow a standard for reviewing his clients' due-process claims, and said he is considering an appeal to the U.S. Supreme Court, which must be filed within 90 days.