• Ambassador and Permanent Representative to the UN in New York, 2009 - 2015. • Chair, UN GA Sixth Committee (Legal), 2013 • Co Chair, UN Working Group on Biological Diversity Beyond National Jurisdiction, 2010 - 2015 Chair, UN Committee on Israeli Practices in the Occupied Territories, 2010 - 2015 • Special Advisor to the
President on the Peace Process and Secretary-General of the Secretariat for Coordinating the Peace Process (SCOPP), April 2006 - January 2007. • Member of the Sri Lankan delegation to the UN GA, 2006 - 2014 • Leader of the UN legal delegation to
North Korea at the invitation of the DPRK Government in 2005. • Patron – Renewable Energy and International Law • Patron – Making Art Everywhere • Advisory Board, Temple of the Tooth Relic, Kandy, 2016 • Chief of the United Nations Treaty Section, New York, 1995 - 2006. • In 1992 he was attached to the
Uruguay Round of Trade Negotiations institutional mechanisms and dispute settlement unit and headed the Trade and Investment Section of the Department in Australia under the GATT/WTO. • In 1989–92 chaired the negotiating group that developed the compliance mechanism under the
Montreal Protocol to the Convention on the Ozone Layer in Geneva and was a member of the Working Group on the liability mechanism under the Basel Convention on Hazardous Wastes. • 1989 posted to the Australian Permanent Mission to the UN in Geneva • In 1988 led the Australian delegation to the UNCTAD Trade and Development Board • Participated in a series of bilateral and multilateral negotiations on aviation matters, trade relations, investment protection, fisheries matters and later led some of the delegations. • Treaty Section of the Ministry •
Department of Foreign Affairs and Trade of Australia since 1983. ==See also==