When a man jumped over the White House fence, ran across the lawn and entered the residence, the Secret Service failed and failed again. One of the most conspicuous and surprising failures was that though it had armed agents on the ground and snipers on the roof, no one fired a shot to stop him. In fact, the agency bragged about not using their guns, saying that "the officers showed tremendous restraint and discipline in dealing with this subject." The agents didn't shoot Omar Gonzalez because they "apparently concluded that he was not armed and did not appear to be...