A federal appeals court has thrown out years of legal proceedings in the already-delayed military commission case against a Saudi charged in the deadly 2000 bombing of a U.S. warship.

An appellate panel in Washington, D.C., says Tuesday that a military judge improperly continued to preside over the case after he sought a job in the Justice Department beginning in 2015. Retired Air Force Col. Vance Spath took a job last year as an immigration judge in the Justice Department.

The unanimous three-judge panel says it can't "permit an appearance of partiality to infect a system of justice that requires the most scrupulous conduct from its adjudicators."

Defendant Abd al-Rahim al-Nashiri is accused of orchestrating the bombing of the USS Cole, which killed 17 sailors and wounded 37.