Class actions are a controversial legal procedure allowing large numbers of plaintiffs with similar claims to join in a single lawsuit against one or more defendants. Civil rights and consumer groups say class actions provide a practical remedy for widespread injuries and help hold businesses accountable for wrongdoing. Business interests insist they lump together claims that may or may not be valid and can force companies to settle instead of incurring the expense and risk of defending a massive lawsuit. The Supreme Court is currently considering one of the biggest class actions ever filed: a sex-discrimination suit brought on behalf of up to 1.5 million current or former workers at Wal-Mart, the giant retailer. Two lower federal courts certified the case for trial, but justices voiced doubts during arguments in March about allowing the case to proceed as a class action. Meanwhile, the court's 5-4 ruling in a separate case allows businesses to enforce contracts that block consumers and employees from using class actions in arbitration.

Kenneth Jost is Supreme Court editor, CQ Press; associate editor, CQ Researcher; and author of The Supreme Court Yearbook since the 1992-1993 edition.