Dozens of military criminal cases have been thrown into limbo because of a legal challenge over whether Defense Secretary Chuck Hagel improperly appointed a judge to the Air Force’s highest court, with attorneys raising questions about the judge’s independence amid increasing pressure over the military’s handling of sexual assault cases.

The military’s top court, the U.S. Armed Forces Court of Criminal Appeals, has sent at least 37 cases back to the Air Force Court of Appeals this month that were handled by former Judge Laurence Soybel. Soybel was a civilian when Hagel — who has publicly criticized the Air Force’s handling of sexual assault cases — appointed him this summer to help alleviate a mounting backlog of criminal cases.

“The secretary of defense has been making a lot of statements related to sexual assaults, and here he is appointing Judge Soybel at will,” said defense attorney Philip Cave, whose client was convicted in a sexual assault case now on appeal. “That creates not just an appointment problem, but a perception problem of whether or not Judge Soybel will be fair.”

The Air Force insists Soybel, who left the court in October, was unbiased and properly appointed. No hearings have been scheduled in the dispute.

The resulting delays have infuriated attorneys and their clients, many of whom have waited years for their appeals to be heard. Defense attorneys say if dozens of Soybel cases have to be reargued in the lower court, it could add six months to a year to each appeal.

Among those is the case of Air Force Sgt. David Gutierrez, who was convicted in 2011 of aggravated assault for exposing multiple sex partners to HIV at swinger parties in Kansas. His attorney, Kevin McDermott, said he was “blindsided” when he learned the dispute had delayed his case just days before he was to argue Gutierrez’s appeal.

“This one case has the potential to remap the entire landscape of HIV testing and prosecution in the United States military,” McDermott said.

Judges on the Air Force Court of Appeals are usually active-duty colonels appointed by the judge advocate of the Air Force. But because the court had a large backlog and didn’t have any active-duty colonels available, the judge advocate appointed Soybel, a retired Air Force major. Soybel had served on the court as an appellate judge from 2006 to 2008, while he was on active duty.

But his civilian appointment was contested, and the Air Force Court of Appeals ultimately ruled that the judge advocate didn’t have authority to appoint non-military personnel to the court, Cave said. Hagel then appointed Soybel, citing his hiring authority as defense secretary.

Cave and other defense attorneys have seized on the dispute, challenging Hagel’s appointment because of concerns about “command influence” — questioning whether the court could have been unfair in its consideration of the cases when Soybel was beholden to Hagel for his job. The attorneys said that because Hagel could dismiss Soybel at any time, the judge could have been biased to side with alleged sexual assault victims.

Because no hearings or other action have been scheduled over Soybel’s appointment, nothing will likely be decided until after the first of the year. Soybel left the appeals court in October to work on labor law issues as a civilian lawyer for the military.

The clerk of court for the Air Force Court of Criminal Appeals, Steve Lucas, declined to comment. Soybel did not respond to emails seeking comment.