The 1996 terrorist attack on Khobar Towers in Saudi Arabia that killed 19 United States airmen was among the defining events of America’s recent experience in the Middle East. But there has been no judicial accountability. With the reported arrest of the man accused of masterminding the crime, a resolution of the case may be closer. The truck bombing at the eight-story dormitory near the Dharan Air Base was the deadliest such attack on American forces since the 1983 bombing of the Marines’ barracks in Beirut that killed 241 American service members. In 2006, a federal court concluded that elements...