A federal judge in Colorado has thrown out a lawsuit challenging the Air Force Academy prayer luncheon scheduled for next week. 

The lawsuit argued the luncheon, scheduled for Thursday, would violate the constitutional separation of church and state because it appeared to be sponsored by the academy and because some faculty feared retribution if they didn't attend, even though the event is officially voluntary.

U.S. District Judge Christine Arguello dismissed the suit, saying neither associate professor of economics David Mullin nor the Military Religious Freedom Foundation had shown the prospect of retribution was real and imminent.

The judge did urge the chaplains sponsoring the luncheon to be clear that it is a voluntary event, and not sponsored by the academy.