A party seeking class certification has the burden to prove, under Rule 23(a), that the class has claims which depend upon a common contention of such a nature that it is capable of classwide resolution – i.e. that the determination of its truth or falsity will resolve an issue that is central to the validity of each one of the claims in one stroke. In a gender discrimination case, proof of commonality necessarily overlaps with the merits contention that Wal-Mart engages in a pattern or practice of discrimination: The crux of a Title VII inquiry is “the reason for a particular employment decision,” and, absent some glue holding together the alleged reasons for those decisions, it will be impossible to say that examination of all the class members’ claims will produce a common answer to the crucial discrimination question. In this case, the Court found that the only corporate policy that the plaintiffs’ evidence convincingly established was Wal-Mart’s “policy” of giving local supervisors discretion over employment matters. Which can be the basis of a Title VII disparate-impact claim, but does not mean that every employee in a company with that policy has a common claim. (In a company of Wal-Mart’s size and geographical scope, the Court found, it is unlikely that all managers would exercise their discretion in a common way without some common direction.) The Court also ruled, under Rule 23(b)(2), that claims for monetary relief may not be certified, at least where the monetary relief is not incidental to the requested injunctive or declaratory relief. The Court found it unnecessary to decide whether monetary claims could ever be certified, because, at a minimum, claims for individualized relief, like backpay, are excluded. Rule 23(b)(2) applies only when a single, indivisible remedy would provide relief to each class member. Rejecting the “Allison test” to determine whether injunctive relief “predominates” over (“incidental”) “monetary” relief for (b)(2) purposes, the Court found that it was unnecessary to decide whether there are any forms of “incidental” relief consistent with the Rule 23(b)(2) and/or the Due Process Clause, because the backpay claims are not incidental to the requested injunction. Wal-Mart, the Court held, is entitled to individualized determinations of each employee’s eligibility for backpay: Even where a plaintiff establishes a pattern or practice of discrimination, the company can then raise individual affirmative defenses and demonstrate that its action was lawful with respect to each claim. The Ninth Circuit, the Court held, erred in approving a “Trial by Formula” because Rule 23 cannot be interpreted to “abridge, enlarge or modify any substantive right” under the Rules Enabling Act, 28 U.S.C. 2072(b). Dukes v. Wal-Mart, 131 S.Ct. 2541 (2011).