This very large class action against Wal-Mart was brought on behalf of 1.5 million female employees around the country for alleged discrimination in pay and promotions. Although the district court certified the class and the Ninth Circuit narrowly agreed, the Supreme Court reversed, deciding that there must be common questions of law or fact, and the critical question here involved whether Wal-Mart engaged in a pattern or practice of discrimination. Answering that question involves scrutinizing millions of employment decisions at once, and unless there is some "glue" holding together the reasons for the discrimination, a class action is not appropriate. There was no proof of a general policy of discrimination in this case. The only corporate policy clearly established was a company policy of giving local supervisors discretion over employment matters, making it unlikely that all managers would exercise their discretion in a common way without some common direction.
In addition, the Court ruled that claims for individualized monetary relief like backpay may not be included in class actions under Rule 23(b)(2), but rather should be brought under Rule 23(b)(3).
Class certification issues are of critical importance to manufacturers caught up in mass tort or mass discrimination claims. Often individual issues relating to particular workplaces, consumers and damages predominate a case, yet some judges certify them for class action status anyway. Such certifications often force companies into expensive settlements in cases of questionable merit. The result in this case is helpful to prevent "Trial by Formula," as described in the Court's opinion.