Lever Brother Company (Lever) (plaintiff) sold dish-washing soap in the United States and, through an affiliate, in Great Britain under identical trademarks. Each trademark was registered in each country. The soaps and packaging were formulated differently to suit the two markets accordingly. An unauthorized gray market for the products caused the British soap to be imported and sold in the United States, resulting in consumer complaints directed at Lever. Lever brought suit against the United States Customs Service (Customs) (defendant) on the grounds that § 42 of the Lanham Act prohibited the import of the soap from Britain containing a United States trademark. Customs relied on a federal regulation that created an exception to § 42 for goods bearing a foreign trademark, if the company that owned the foreign trademark was under common ownership with the company that owned the United States trademark. Customs argued that the exception to § 42 was valid, because § 42 only prohibits the use of a trademark that copies or simulates a United States trademark. The district court found that the exception did not comply with the plain meaning of § 42 and granted summary judgment in favor of Lever. Customs appealed to the United States Court of Appeals for the District of Columbia Circuit.