Editors' Summary: On May 20, 1994, a three-member dispute panel of the General Agreement on Tariffs and Trade (GATT) held that the U.S. Marine Mammal Protection Act (MMPA), which provides authority for the United States to embargo tuna from other countries, violates GATT. The ensuing debate has focused on two issues: (1) the decision's effect on the intersection of domestic environmental protection/conservation measures and international trade law in the context of GATT; and (2) how the United States should respond in light of diplomatic pressure, public perception that the United States might be relinquishing sovereignty, and efforts to maintain GATT's integrity. The author describes the background of the dispute and the panel's decision, including relevant MMPA provisions and GATT processes and provisions. He also comments in detail about the panel's decision with respect to the MMPA-based tuna embargoes in light of a prior GATT panel decision that held that a U.S. embargo on Mexican tuna and tuna products harvested in the eastern tropical Pacific violated GATT. The author also delves into the GATT review process and considers whether it is optimal for environmental disputes. Finally, the author makes several recommendations, including suggested changes to GATT review of domestic environmental laws, and advice that the United States alter the MMPA to conform with GATT and strongly oppose the adoption of the panel decision by the GATT Council.