Attorneys for an Air Force officer who was charged with rape, adultery and other crimes assembled a unique argument that the military ban on extramarital sex discriminates against heterosexuals because it doesn't specifically include same-sex couples.

Lawyers for Air Force Col. Eugene Caughey challenged the adultery provision Monday in a military court at Peterson Air Force Base, Colo., arguing that the half-dozen adultery charges against Caughey should be thrown out because they violate the colonel's constitutional rights.

Caughey's attorneys said the military defines "adultery" as sex between a man and a woman, and therefore doesn't hold same-sex couples to the same standards, the Colorado Springs Gazette reported. Military prosecutors argued the adultery ban does apply to same-sex couples. The judge hasn't ruled on the argument.

Caughey is charged with raping a woman at Schriever Air Force Base, also in Colorado, in late 2014 or early 2015. He's also accused of committing adultery several times, photographing his exposed genitals while in uniform and groping women. His court-martial is scheduled in August.

Caughey is a 24-year Air Force veteran.

Eugene Fidell, who teaches military justice at Yale Law School, said Tuesday this is the first time he's heard anyone try to make the discrimination argument in a military court, reports Associated Press.

He declined to say whether he thought the argument would succeed.

Fidell said the military needs to update its court-martial manuals now that same-sex marriage is legal.

"This is the brave new world that we live in," he said. "The teachers of family law and teachers of gender in law schools are going to have to discuss this case."

Few other jurisdictions punish adultery as a crime, but the military still outlaws it on the grounds that it weakens discipline. Fidell said it could be handled administratively, without resorting to criminal charges. "The military would be well advised to just get rid of it," he said.