When New York City police arrested South Sudanese diplomat Charles Dickens Imene Oliha after a woman accused him of rape, it raised the question: What exactly is “diplomatic immunity”? Mr. Oliha allegedly propositioned the woman while she was walking her dog and then, when she refused, forced himself into her apartment and sexually assaulted her. NYPD’s Special Victims Unit arrested Mr. Oliha but released him when he said he was a diplomat. South Sudan’s Ministry of Foreign Affairs recalled Mr. Oliha and flew him home a few days later.