A Florida gun store operator has banned Muslims from his establishment, arguing that he has a right to deny service to anyone he considers a threat. Andy Hallinan made his decision after the shootings at military installations in Chattanooga, Tenn., last week. Florida Gun Supply of Inverness, Fla., was declared a “Muslim-free zone” in a video Hallinan posted online over the weekend. In response, President Barack Obama’s Department of Justice announced that it would launch a civil rights investigation into Hallinan’s establishment. That’s the Obama administration: a radical Islamic extremist kills five American servicemen and the Pentagon suggests that recruiting...