The obligations of international trade law hinge upon the question of what constitute like products. Trade disputes will often involve an examination of whether the products in question are in competition with one another. The most common term used for this test is to ask whether they are like products - that is to ask whether products are sufficiently similar for consumers to see them as substitutable - and thus whether they are subject to the rules of the WTO and GATT. The central thesis of this book is that despite the centrality of the principle of 'like products' to the WTO, it has not been consistently interpreted, and therefore the risk of discriminatory practice remains. The author, through analyzing legal and economic arguments, sets about defining the concept of 'like products' in such a way as to consistently give effect to WTO aims.