Quantitative restrictions are regulated by Article XI of the GATT 1994, which provides for the general elimination of all "prohibitions or restrictions other than duties, taxes or other charges" on imports and exports of goods, which can be "made effective through quotas, import or export licences or other measures". Article XI does not provide an exhaustive definition of what constitutes a quantitative restriction. While identifying prohibitions (i.e. bans) on imports or exports is usually straightforward, as customs and other authorities usually maintain lists of goods that cannot be traded, it may prove more challenging to identify measures that qualify as "restrictions other than duties, taxes or other charges". Quotas (i.e. an absolute quantity or monetary limit on the importation or exportation of a product) and licenses are expressly recognized as measures that could be used to make effective a prohibition or a restriction, but Article XI acknowledges that "other measures" could be put in place to prohibit or restrict trade.

The implementation of Article XI has been examined in numerous GATT and WTO disputes where the Panels and the Appellate Body have found that this provision includes all measures prohibiting or restricting the importation, exportation, or sale for export of products other than measures taking the form duties, taxes or other charges. These would include, for instance, certain regulatory regimes, discretionary licensing schemes, price requirements, and restrictions on circumstances of importation, fall under this provision.

No. Although Article XI:1 of the GATT 1994 provides for the general elimination of quantitative restrictions, Members are allowed to introduce or maintain them in a limited number of circumstances, as exceptions. These include, for example, the specific exceptions set out in the GATT 1994, including the carve-outs of Article XI:2, the general exceptions ( GATT Article XX), or the national security exceptions (GATT Article XXI), among others. There are, in addition, exceptions provided for in other WTO agreements, such as the Agreement on Safeguards, the Agreement on Balance of Payments, and the Agreement on Agriculture.

Whenever a quantitative restriction is imposed or maintained by a Member, as a result of one of these exceptions, then Members must administer them on a non-discriminatory basis, in accordance with Article XIII of the GATT 1994.

Several Members have also notified that they impose prohibitions and restrictions as a result of international obligations undertaken outside the WTO framework, including the Montreal Protocol on Substances that Deplete the Ozone Layer, the Convention on International Trade in Endangered Species (CITES), the Basel Convention on hazardous waste, etc. When a Member applies a prohibition or restriction on international trade as a result of one of such conventions, it must also notify it under the QR Decision and provide an indication of which WTO provision, in its opinion, allows the introduction of the measure. For example, Members that have notified measures maintained pursuant to a multilateral environmental agreement have typically indicated Article XX of the GATT as legal justification for the measures.