He also served briefly as dean at Northwestern University. For his academic and government service, he received the Presidential Order of Merit award, a Ph.D. honoris causa from the University of Pangasinan and a doctorate degree in public administration from the Polytechnic University of the Philippines. Quisumbing had special training in Management of Public Agencies at the Cornell University Graduate School, in Research at Georgetown University Communications at the Michigan State University, and in Public Sector Negotiations at Harvard University. While serving as a trade union officer, he attended international law and labor conferences in Geneva, Moscow, Beijing and Jakarta. His published works include: Constitutional Control of the Election Process; Compensation in Land Reform Cases, Comparative Public Law Study; Asean Comparative Law (Vol. IV ed., Corporation Law) in the EEC and Asean, Two Regional Experiences; Law on Taxation in the Philippines; Labor Law and Jurisprudence (1992–1998); and Access to Justice, a lecture delivered before the 1993 Asean Law Association Conference in Singapore. Quisumbing was married to Dr. Purificacion Valera Quisumbing, who died in December 2011, the former Chairperson of the Commission on Human Rights. They had two children: Josefa Lourdes and Cecilia Rachel. Known as an activist, Quisumbing had a long record of union service since the 1970s. He was the former Chairman of the Confederation of Industry Unions of the Philippines, (CINUP), former president of the National Alliance of Teachers and Allied Workers (NATAW), and former secretary-general of the Lakas Manggagawa Labor Center (LMLC).