In the United States, antitrust law strives to eliminate price fixing affecting the U.S. market. That price-fixing activity sometimes occurs outside the United States, and some defendants ensnared in antitrust inquiries have invoked a plausible defense that can be summarized as: A foreign government made me do it! Faced with this defense, U.S. courts are tasked with the complex charge of construing the law of foreign nations. In Animal Science Products v. Hebei Welcome Pharmaceutical, the Supreme Court has been asked to answer whether, in such cases, a U.S. court is required to defer to an interpretation of foreign law offered by a foreign sovereign appearing in the litigation.

An antitrust case in New York presented the issue in the context of Chinese law. In 2005, Animal Science Products Inc., a Texas-based company that uses Vitamin C in the production of livestock supplements, brought action in the U.S. District Court for the Eastern District of New York against Hebei Welcome Pharmaceutical Co. and other Chinese Vitamin C exporters, alleging that they had coordinated and fixed minimum prices for exports of Vitamin C to the United States in violation of U.S. antitrust laws. Interestingly, Hebei Welcome did not contest that it had fixed prices with other Chinese Vitamin C exporters. Instead, Hebei Welcome argued that it could not be liable for price fixing under U.S. law because Chinese law required it to fix export prices with other manufacturers. As a result, the case focused primarily on whether Chinese law in fact required Vitamin C exporters to fix export prices.