Companies in Europe and Japan are increasingly the target of private antitrust litigation. These lawsuits are being facilitated by favorable case law, legislative changes, and a growing awareness of antitrust remedies in all layers of society. This book analyzes and compares this burgeoning area of litigation in the European Union and Japan. It examines the legal framework for these actions and takes stock of the hundreds of actions for damages and injunctive relief that have been brought in Japan and the EU. It also looks at the novel contexts in which private litigants are invoking antitrust violations, such as in derivative suits and in actions to challenge arbitral awards. Finally, the book assesses the impact of private litigation on the enforcement of antitrust law and shows how Japan’s experience can be useful for Europe and vice versa in shaping future reforms.