A group of United States retailers, including Gap, J. C. Penney and Target, suffered a setback this week when a federal judge ruled that thousands of garment workers on the Pacific island of Saipan could sue the companies and their contracted factories as a class. The group also failed to block a US$ 8.7 million settlement by 19 other retailers, including Tommy Hilfiger and Liz Claiborne, which sets a strict code of conduct and opens up factories on the island to independent monitoring.