Director of the Conflict Prevention and Peace Forum (CPPF) in New York, William O'Neill has specialized in humanitarian law, human rights and refugee law. Having worked on the areas of judicial, police and prison reforms in Burundi, Liberia, Sierra Leone, South Sudan, Timor Leste, Nepal and Bosnia-Herzegovina, O' Neill has written extensively on peacekeeping and peace-building. He has also developed and taught courses on human rights, rule of law and peacekeeping for several peacekeeping training centers at a variety of institutions including UN- and government-sponsored training centers chiefly participated by senior military, police and humanitarian officials from different countries. In 2008, O'Neill was appointed as the visiting professor of law and International Relations at the Scuola Sant’Anna, Pisa, Italy’s premier graduate faculty in public affairs to teach a course on civilians in peacekeeping operations. Also, he has published widely on rule of law, human rights and peacekeeping, including, Kosovo: An Unfinished Peace and Protecting Two Million Displaced: The Successes and Shortcomings of the African Union in Darfur.
O'Neill also has the experience of serving as the chief of the UN Human Rights Field Operation in Rwanda. He also led the Legal Department of the UN/OAS Mission in Haiti. He was a senior advisor on Human Rights in the UN Mission in Kosovo. He investigated mass killings in Afghanistan for the High Commissioner for Human Rights. He has also conducted an assessment of the human rights situation in Darfur and trained the UN's human rights monitors stationed there. At the request of the UN's Executive Committee on Peace and Security, he chaired a Task Force on Developing Rule of Law Strategies in Peace Operation.