Professor Robert Merges’ latest book, American Patent Law: A Business and Economic History, offers a comprehensive recounting of the U.S. patent system from 1790, with an emphasis on how patents have been used by private enterprise for the pursuit of business goals. It highlights how Congress and the courts have adapted patent rules to support socially beneficial business practices, and tried (at times successfully) to modify those rules to re-channel investment and effort away from socially harmful practices, such as extortionate litigation.