A recent case relating to this clause involved two United States diplomats who were murdered by terrorists in Sudan in 1973. In 1976 Congress amended the Federal code to impose Federal criminal liability on persons killing or trying to kill diplomats or other internationally protected persons. Forty-four senators wrote to the Attorney General in 1976 asking that the Department of Justice (DOJ) consider indicting Yasir Arafat, who had allegedly given the instructions to the terrorists. However, the DOJ concluded that the United States lacked jurisdiction, stating that the ex post facto clause barred the retroactive application of the 1976 amended law to the 1973 terrorist act. However, this clause only prevents the United States from exercising jurisdiction if in 1973 it could not have exercised universal jurisdiction as a matter of customary law over terrorist acts against diplomats. Once a law like the 1976 law is passed, the United States should exercise universal jurisdiction, even if this entails retroactive application of the statute. 120 references.