Since the mass shooting in Aurora, CO, the media have focused particularly on two issues: the ease with which the perpetrator acquired an assault rifle and the possibility that he is mentally ill, issues that are peripheral to America's gun violence problem, explained Jerry Ratcliffe, chair of criminal justice at Temple, in an opinion piece. “Reducing the opportunity to commit crime by increasing the effort it takes has repeatedly been shown to prevent crime. This is not rocket science; it's crime science,” he said.