In the Walmart case, the Supreme Court ruled against certifying a class-action lawsuit brought by 1.5 million female employees alleging gender discrimination in pay and promotion practices. The Court determined that the plaintiffs failed to establish the necessary commonality of claims as mandated by Federal Rule. It emphasized that commonality goes beyond the mere presence of a common question; it requires a shared answer that could resolve the entire case. The Court found that the plaintiffs’ claims lacked commonality because they did not identify a common policy or practice at Wal-Mart that could be challenged as discriminatory.