From the outset, GATT and now the WTO have allowed Member States to enter into free trade unions and zones, as an exception to the fundamental principle of non-discrimination established in the most favoured nation clause of Article I. Article XXIV of the GATT set the terms of the exchanges. The main principle is to facilitate trade between constituent countries and not to remove trade barriers for other WTO members who are not parties to the ATR. During the Uruguay Round, Article XXIV was, to some extent, clarified and updated by interpretation. Preferential trade agreements between developing countries are governed by a 1979 enabling clause. With respect to trade in services, the conclusion of the RTA is governed by Section V of the GATS. To date, more than 200 ATRs have been notified to THE GATT/WTO. Of these, 121 agreements notified under GATT Article XXIV are still in effect today, 19 under the enabling clause and 12 under Section V of the GATS. The CRTA is currently reviewing more than 100 agreements. Most WTO members are now also parties to regional trade agreements (ATRs). These numbers have expanded considerably in number, size and coverage, and their numbers continue to increase.
It is estimated that more than half of world trade is now done under preferential trade agreements. RTAs exist on every continent. Among the best known are the European Union, the European Free Trade Association (EFTA), the North American Free Trade Agreement (NAFTA), the Southern Common Market (MERCOSUR), the Association of Southeast Asian Nations (ASEAN) and the East and South African Common Market (COMESA). The issues raised in the debate on regionalism are multidimensional and interconnected. Some are primarily legal. Thus, Article XXIV stipulates that all trade between constituent members is covered by the RTA, and the same condition is set by Article V of the GATS, which requires significant sectoral coverage in the services sector. But there is no agreement among the members on the importance of these formulations and, indeed, many agreements neglect important and sensitive areas such as agriculture and textiles. Hence the difficulties faced by WTO members in assessing the coherence of ATRs. Other issues are institutional and present potential differences between the rules of the RTA and those of the WTO.
Trade rules have evolved over time from tariff reductions to regulatory policy, both regionally and multilaterally. This is the case, for example, with anti-dumping measures, subsidies or standards; Especially since some of the recent ATRs contain non-WTO provisions, such as investment policy or competition policy.