He was one of the civilian Promoters of the Siamese Revolution of 1932 that changed the country's form of government from absolute to constitutional monarchy. He was closely associated with Pridi Banomyong. In the government of Field Marshal Plaek Phibunsongkhram he served as Minister of Foreign Affairs, but resigned when Phibunsongkhram led Thailand into World War II alongside Japan. Direk became a member of the Free Thai Movement "(Seri Thai)" alongside Pridi, who fought for the full sovereignty of Thailand and against collaboration with Japan. After the end of war, he served as Minister of Justice, Finance, Foreign Affairs and Deputy Prime Minister in several short-lived cabinets. From 1949 to 1952 he was the first dean of the Faculty of Political Science, Thammasat University.