He was a minister under Ferdinand Marcos, holding the post of Minister of Labor from 1967 to 1986 with a small break 1971 to 1972. He was an author of the 1987 Constitution. He was elected to the senate in 1992, and was elected President of the Senate in 1999. In 2002 he was made Secretary of the Department of Foreign Affairs by president Gloria Macapagal-Arroyo.