Patents play an important role in inducing the investment needed to transform basic discoveries into the practical innovations that contribute to long-term economic growth. But patents also can generate a variety of social costs which, if unchecked, can unnecessarily impede competition, inhibit innovation, impair the integrity of the marketplace, and reduce overall social welfare. Wrongful Patent Assertion provides the first comprehensive, comparative overview of how the world's leading jurisdictions for patent litigation employ different bodies of law and legal doctrines-including antitrust and unfair competition law, as well as other generally-applicable legal principles-to regulate the enforcement of patent rights, and how these efforts might be improved. Among the topics discussed are the circumstances under which owners are or should be liable for the actual or threatened enforcement of patent rights; what sort of harms should matter in assessing liability; and the circumstances under which liability should depend, in whole or in part, upon the patent having been adjudicated invalid or not infringed ex post, or upon evidence that the assertion of rights enables the owner to extract benefits beyond the patent's probable ex ante scope; or alternatively, upon some reason independent of the patent's actual or probable validity or infringement.