Consumer preferences and the National Treatment Principle : emerging environmental regulations prompt a new look at an old problem EMILY BARRETT LYDGATE* Ph.D. Candidate, King’s College London Abstract : Should consumers’ preference for ‘ green ’ products help justify, from a WTO perspective, emerging regulations such as restrictions on trade in non-sustainable biofuels ? Despite the role consumer preferences have played in WTO disputes, in association with the ‘like’ products concept, there has not been enough focused examination of their specific influence, particularly in disputes on ethical public policy issues, such as environmental or health regulations. To this end, this paper examines key GATT Article III disputes, pointing out that they included attempts both to measure, and also to interpret, consumer preferences. The latter approach becomes more tempting when consumer preferences are difficult to measure ; import bans or restrictions associated with ethical public policy regulations can bring about such a situation. A hypothetical dispute about EC biofuels sustainability criteria demonstrates this problem. Options to make the concept of consumer preferences more coherent include limitations on how they can be invoked, and an increased commitment to capturing them through measurement. 1. Introduction Consumer preferences and Article III This paper focuses on how consumer preferences have been interpreted and applied in deliberation of WTO disputes under the GATT National Treatment Principle (‘Article III’). The entry point for the analysis is the concept of ‘like’ products. This concept, which recurs throughout the GATT and WTO Agreements, is an influential aspect of WTO law in general (Choi, 2003). The consideration of what constitutes ‘like’ products has differed both between, and within, relevant Articles, and the slightly varied phrasing of these Articles also influences their * Email: emily.lydgate@kcl.ac.uk Many thanks to Dr Federico Ortino of King’s College London for thoughtful review of this paper, and helpful suggestions. Thanks, also, to Alan Winters, and an anonymous reviewer, whose insightful comments were of great use. Any remaining errors are the author’s alone. World Trade Review (2011), 10 : 2, 165–188 f Emily Barrett Lydgate doi:10.1017/S1474745610000492 165