John Stewart Service (August 3, 1909 – February 3, 1999) was an American diplomat who served in the Foreign Service in China prior to and during World War II. Considered one of the State Department's "China Hands", he was an important member of the Dixie Mission to Yan'an. Service correctly predicted that the Communists would defeat the Nationalists in a civil war: he and other diplomats were blamed for the "loss" of China in the domestic political turmoil following the 1949 Communist triumph in China. In June 1945, Service was arrested in the Amerasia Affair in 1945. The prosecution sought an indictment for espionage, but a federal grand jury unanimously declined to indict him. In 1950 U.S. Senator Joseph McCarthy launched an attack against Service, which led to investigations of the reports Service wrote while stationed in China. Numerous loyalty board cleared Service, but a final one suggested there was "reasonable doubt" as to his loyalty. This opinion forced Secretary of State Dean Acheson to fire Service. In 1957 the U.S. Supreme Court ordered his reinstatement in a unanimous decision, finding that Acheson's action had been illegal because "it violated Regulations of the Department of State which were binding on the Secretary."