Michael Behenna was convicted of unpremeditated murder and sentenced to 25 years in a military prison.
An Army first lieutenant, Behenna was serving as a platoon leader in Iraq in 2008 when an insurgent attack with an improvised explosive device ripped through his patrol, killing two soldiers and three Iraqi civilians.
Later, Behenna interrogated a suspected insurgent linked to the deadly attack by intelligence reports that identified the suspect as a member of the local "al-Qaida in Iraq IED [improved explosive device] cell."
Alone with his prisoner in the desert except for his translator, Behenna pulled his pistol and shot him twice, killing him. He later said the prisoner made a move to grab the pistol, a fact disputed by the translator.
A bare majority of the Court of Appeals for the Armed Forces ruled that Behenna "lost the right to act in self-defense as a matter of law" because it was an unauthorized interrogation and he had drawn his pistol.
"Even assuming that a service member becomes an initial aggressor by pointing a firearm at a suspected enemy without authorization," Behenna's petition to the Supreme Court said, "the common law of self-defense does not categorically equate gun pointing with 'deadly force' that wholly forfeits the defender's right to repel a lethal attack."
The military appeals court's decision "is not only wrong, but dangerous," the petition said. "It puts service members in combat zones in a more vulnerable position than their civilian law enforcement counterparts."
The U.S. Supreme Court rejected review without comment.
NBC reportedly holds celebs hostage to Jimmy Fallon's show
Aaron Carter is still in love with Hilary Duff