This paper was prepared by Katia Yannaca-Small, Legal Advisor, Investment Division, Directorate for Financial and Enterprise Affairs, OECD. Thanks are due to Catriona Paterson, a consultant to the Investment Division, for research input. It has been developed as an input to the Investment Committee’s work aimed at enhancing understanding of the "umbrella clause" in international investment agreements and has benefited from discussions and a variety of perspectives in the Committee. It was also a subject for discussion at an APEC-UNCTAD Regional Seminar on Investor-State Dispute Settlement in Mexico City on 9-10 October 2006. The paper as a factual survey does not necessarily reflect the views of the OECD or those of its Member governments. It cannot be construed as prejudging ongoing or future negotiations or disputes pertaining to international investment agreements.