William V. O'Brien, Professor of Government Emeritus at Georgetown University, died on July 8, 2003, at his home in Washington of head injuries suffered in a fall.

Specializing in international law and ethics, O'Brien was one of the world's leading experts on just war doctrine and international law dealing with the use of military force. He was the author of many books in this area, including: The Conduct of Just and Limited War; Law and Moralitaz Israel's War with the PLO; Nuclear War, Deterrence, and Morality; and War And/Or Survival.

O'Brien received his B.S.F.S., M.A., and Ph.D. from Georgetown and joined the University's faculty in 1950. A masterful teacher, he taught thousands of undergraduate and graduate students until his retirement in 1993. He was often praised by his students for his brilliant and engaging lectures. During his tenure at the University, O'Brien was chair of the Institute of World Policy and twice served as chair of the government department. He was instrumental in establishing the Goldman Visiting Israeli Professorship at the University. In recognition of his deep devotion to Georgetown, he was awarded an honorary doctorate from the University in 1992. The following year, the University established the William V. O'Brien Lecture in International Law and Morality as a lasting tribute to his life's work.

O'Brien joined the U.S. Army Reserve Office Training Corps while in college and was called into active duty during World War II. In 1952, he was commissioned as an officer in the Army Reserve and rose to the rank of Lieutenant Colonel. During his time as a reserve officer, his work took him to the Pentagon and a variety of other assignments.

Dr. O'Brien was an active Catholic layperson and was called upon to offer advice to Church leaders on a number of occasions. He was active in the Catholic Association of International Peace and was elected as its president in 1961. In 1967, he chaired the International Relations Committee at the Third World Congress of the Law Apostalate held at the Vatican. He was also deeply committed to ecumenical work and was quite active in the Council on Religion and International Affairs (now the Carnegie Council on Ethics and International Affairs).

O'Brien was married to the former Madge L. Roberts, who passed away in 1996. He is survived by his sister Kathleen O'Brien and his brother Daniel O'Brien.