Patent misuse is an affirmative defense to an action for patent infringement or for royalties under a license that arises when the patentee engages in certain anticompetitive conduct, or conduct contrary to public policy, using the patent in suit. The misuse doctrine protects against conduct that impermissibly extends intellectual property rights beyond their lawful scope. As a result, the modern misuse doctrine straddles the intersection of intellectual property law and antitrust—it borrows from both, but is completely at home in neither. This makes misuse a challenging landscape to navigate for antitrust and intellectual property practitioners alike. This book provides an update on new developments in the law since the first edition, and provides a practical, practitioner-orientated approach to understanding and applying misuse doctrine.