In early 1950, Prof. Marut Bunnag established the Marut Bunnag Law Office near the Southern Bangkok Civil Court in the area of Pranakorn, Bangkok, Thailand. He was appointed to be the Lawyers' Association of Thailand Secretary General, and subsequently, became its President for some 10 years. Prof. Bunnag became increasingly interested in international legal business, and he joined a number of international lawyers' organizations, e.g., the World Peace Through Law Centre; the International Bar Association; and the Law Association for Asia and the Pacific, in which he served as its President.
Prof. Marut Bunnag
One other result of Prof. Bunnag's growing interest in international legal matters was that, in 1971, he suggested to some colleagues to collaborate in establishing a truly international law firm with the basic aim of serving the legal requirements of foreign investors and businessmen; This firm became the Marut Bunnag International Law Office. Additionally Prof. Bunnag has also served the Thai people as Minister of Public Health in two government administrations, and also as Minister of Justice, and Minister of Education, Furthermore, he was appointed the Speaker of the House of Representatives and President of the National Assembly.
At present, he is still a part time lecturer in many institutions such as the Thai Bar Association, Thammasart University, Chulalongkorn University, Mahidol University, and Ramkhamhaeng University, etc.
The current managing director of Marut Bunnag International Law Office is Prof. Marut Bunnag's son, Dr. Rujira Bunnag, who received an LL.M. in Admiralty law, at Tulane University, and an LL.M., from the University of Pennsylvania, U.S.A., PhD, Mahachulalongkornrajavidyalaya University.