In Wal-Mart v. Dukes (2011), the Supreme Court ruled against a group of around 1.5 million women who wanted to file a class-action lawsuit against Wal-Mart for gender discrimination. The Court said the group could not move forward as a class because they failed to prove “commonality”, a legal requirement that all members of a class share a common issue that can be resolved in one stroke for everyone. The women argued that Wal-Mart’s corporate culture allowed for discrimination, but the Court said there wasn’t enough proof of a company-wide policy of discrimination. Instead, decisions were made at the local level by individual managers, so the experiences of the women were too different to be treated as a single case.

The decision made it harder for large groups of employees to bring class-action lawsuits against employers. The Court said that in order for a class to be certified, there needs to be clear evidence that all members of the group were affected in the same way by a common practice or policy. Because the women’s cases involved different managers and different stores, the Court felt they didn’t meet this standard. This ruling raised the bar for proving commonality in future class-action lawsuits, especially in workplace discrimination cases.