Costco Wholesale Corp. workers who sued the retailer for genderbias will be able to proceed with their claims as a group.

U.S. District Judge Edward Chen in San Francisco certified aclass, or group, of plaintiffs, seeking monetary relief thatincludes several hundred women employed since 2002 who have beensubject to the Issaquah, Washington-based company's system forpromotion to management positions.

Costco “offers numerous competing explanations for the observedgender disparity in promotions,” Chen said in yesterday's ruling.“None of these explanations undermine the companywide nature of thechallenged policies and their disparate effects.”