In Walmart v. Dukes (2011), the Supreme Court ruled 5 to 4 to throw out the class action lawsuit brought by over one million female employees. The Court did not rule on whether discrimination occurred, but instead decided that the case could not move forward as a single collective lawsuit.

The Court justified its decision based on the legal concept of commonality. For a class action lawsuit to proceed, the plaintiffs must prove they all suffered a common injury stemming from the exact same corporate policy. The majority argued that the women failed to prove commonality because Walmart had an official policy against discrimination and left pay and promotion decisions up to the subjective discretion of local store managers. Because thousands of different managers made these choices across the country, the Court ruled there was no single company-wide policy tying the women together. Ultimately, they decided the employees did not share a common legal injury, turning a massive structural issue into thousands of isolated, individual cases.