Tuna I: a dispute in the GATT between Mexico and the United States. The dispute arose from a prohibition mandated by the United States Marine Mammal Protection Act (MMPA) of 1972 concerning the "taking" (harassing, hunting, capture, killing or attempts to do so) of marine mammals and the import of marine mammals except where an authorization had been issued. In specified circumstances, the ban on imports could be extended to other fishery products. The aim of the Act was to reduce to insignificant levels approaching zero the incidental kill or serious injury of marine mammals during commercial fishing. A practice targeted particularly by the Act was purse-seine fishing of tuna, a fishing technique aimed at the catch of yellowfin tuna fish. At the same time, it produced, especially in the case of the Eastern Tropical Pacific Ocean, significant catches of dolphins because they tend to occupy the same waters as yellowfin tuna. The Act set numerical limits on the taking of marine mammals, and there were procedures in place for other countries to show that they met the requirements of the Act. On 10 October 1990 the United States imposed an embargo on tuna from Mexico in retaliation to the alleged taking of marine mammals. This was confirmed on 3 April 1991 with the inclusion in the ban also of Venezuela and Vanuatu. The Act provided that embargoes are effective against intermediary countries also, and this provision was enforced through the need for a certificate of origin. The ban on imports from offending countries was reinforced through a labelling standard for any tuna exported from or offered for sale in the United States. Mexico made three main claims. First, the embargo provisions contained in the Act violated GATT Article XI (General Elimination of Quantitative Restrictions), and their enforcement against specific geographical areas was in breach of Article XIII (Non-discriminatory Administration of Quantitative Restrictions). Second, the condition of comparison between yellowfin tuna regulation in the United States and other countries violated Article III (National Treatment), especially as it relates to "all laws, regulations or requirements" affecting products, rather than producers. Third, the possibility of an import ban on all fishery products from Mexico also violated Article XI. The United States rejected all of these claims. As in a similar case launched against it by Canada in 1982, the United States based its defence mainly on GATT Article XX (General Exceptions) which allows a GATT member to disregard other GATT provisions in strictly defined circumstances. Accordingly, it claimed that if there was any doubt whether the United States measures were consistent with the GATT, Article XX would ensure that the measures were not inconsistent with its obligations under the GATT. Its measures were necessary to protect the lives or health of dolphins and were therefore justified under Article XX(b). A government could in any case prohibit imports of a product to protect the life or health of humans, plants or animals outside its jurisdiction. The United States also invoked Article XX(g) covering measures "relating to the conservation of exhaustible natural resources if such measures are made effective in conjunction with restrictions on domestic production or