John Ching Hsiung Wu served as an adviser to the Chinese delegation at the 1945 UN Conference on International Organization, and was later appointed as a judge to the Permanent Court of Arbitration in the Hague.
Wu served as an adviser in the Chinese delegation to the 1945 United Nations Conference on International Organization in San Francisco and served as the Chinese ambassador to the Vatican in 1947-49. In 1957, Wu was appointed a judge of the Permanent Court of Arbitration in the Hague. 
