Responding to fears of escalating violence in Mexico that could spill over the border into Texas and other states, the U.S. government has stepped up law enforcement. Border Patrol and Drug Enforcement Administration agents were sent to shore up local law enforcement, and to their credit the violence has not spread to those communities and regions. In fact, El Paso — just across the border from Ciudad Juarez, which ranks as one of the most dangerous places in the world — is ranked as one of the safest cities in the United States. Unfortunately, the stepped-up enforcement in border cities...