Lt. Col. Victor Fehrenbach is asking a federal court in Idaho to block the U.S. Air Force from discharging him under “Don't Ask, Don't Tell,” the 1993 law that prohibits gay troops from serving openly.

Fehrenbach has been under investigation since 2008, when a civilian man accused him of sexual assault.

The military quickly placed him on desk duty at Mountain Home Air Force Base in Idaho as the investigation continued. In a statement to Boise police officers, the 40-year-old officer acknowledged he had sex with his accuser but said it was consensual. Within three weeks, Fehrenbach was cleared of the sexual assault allegation. But the Air Force continued to investigate whether to discharge the highly-decorated flight officer for violating “Don't Ask.”

Fehrenbach, who is being advised by the gay rights group Servicemembers Legal Defense Network (SLDN), filed suit on Wednesday to block his discharge. The group says a recent Air Force Personnel Board recommendation to Secretary Michael B. Donley indicates the discharge is imminent. The board only moves a case up to the secretary when recommending separation.

Under new regulations put in place by Secretary of Defense Robert Gates, third party outings are placed under greater scrutiny, but that policy has yet to be tested.

“Our nation is on the verge of firing a highly decorated combat aviator, an American hero,” Aubrey Sarvis, executive director of SLDN, said. “The Air Force Secretary can do the right thing and retain Lt. Col. Fehrenbach under the Pentagon's own recently revised regulations on 'Don't Ask, Don't Tell.'”

“If Secretary Donley does not step in, this nation will lose a service member worth $25 million in training whose skill sets are desperately needed today,” he added.

Fehrenbach is 13 months from a 20-year retirement. If discharged, he would lose his right to a pension, according to documents filed with the court.

The filing also says that Fehrenbach served in the former Yugoslavia, Afghanistan and Iraq.

“He flew the longest combat sorties in his squadron's history, destroying Taliban and Al Qaeda targets in support of Operation Enduring Freedom and Operation Iraqi Freedom. And after the Sept. 11th attacks, Fehrenbach was hand-picked to protect the airspace over Washington, D.C.” the documents say.

The case relies heavily on the 2008 Witt vs. Department of the Air Force ruling, which found that discharging troops for their sexuality was unconstitutional unless the military could show an overriding government interest. The Witt ruling only applies to the Ninth Circuit, which includes Idaho.

The House of Representatives voted in May to repeal the policy, and the Senate is expected to debate the issue in September. However, Republicans, led by Arizona Senator John McCain, have said they'll fight against repeal.