He was Secretary of Foreign Affairs during the 1980s under President Miguel de la Madrid and is a former judge of the International Court of Justice.

He then pursued post-graduate studies, specialising in international law at Queens' College, Cambridge in the United Kingdom (1966).

His other academic activities have seen him work at the Centro de Investigación y Docencia Económicas (CIDE) and the UNAM.

Between those two diplomatic postings, from December 1982 to 1988, he served as Secretary of Foreign Affairs under President Miguel de la Madrid.

In 2012, Sepúlveda-Amor was elected by the judges of the ICJ to serve as its vice-president, for a three-year term beginning February 6, 2012.