The future of antitrust undoubtedly includes an element of private enforcement and recovery. In private enforcement actions asserting antitrust claims on behalf of individuals or firms, the alleged harm may be spread across a large number of purchasers or sellers, making individual actions impractical and requiring recovery through collective actions.

In the United States, private enforcement through collective actions is not new: it has been a critical part of antitrust enforcement for decades. Rule 23 of the Federal Rules of Civil Procedure sets forth the standards for obtaining class certification and is augmented by a long history of court precedent that sets a very high bar for proof at the class certification stage. Outside the United States, in contrast, private actions are still developing, but decisions in Canada and the United Kingdom suggest a lower bar for class certification.

Many jurisdictions around the world are just starting to allow collective actions in competition cases. In deciding on the appropriate standard of proof at the class certification stage, policymakers in emerging jurisdictions may use economic analysis to help make difficult choices. In this article, after surveying the various key standards, we identify different ways in which departures from an optimal standard for judging class actions could, under certain assumptions, harm certain parties or lead to losses in efficiency.