The US Court of Appeals for the Ninth Circuit has issued a significant decision affirming the certification of the largest class action since the adoption of Federal Rule of Civil Procedure 23. In Dukes v. Wal-Mart Stores, Inc., Nos. 04-16688 and 04-16720, a divided en banc court ruled, 6 to 5, that the district court did not abuse its discretion in certifying a class of as many as 1.5 million female employees who worked in Wal-Mart’s 3,400 stores at any time after December 1998 for gender discrimination claims based on pay.