Intellectual property rights have undergone a significant expansion over the last half century, particularly since the Copyright Act of 1976. In The Political Economy of Intellectual Property Law, William M. Landes and Richard A. Posner (AEI Press; July 1, 2004) attempt to explain this expansion of intellectual property rights, and how it could have coincided with the deregulation movement. Should intellectual property be thought of as a form of regulation? Why did the movement for greater protection of intellectual property coincide with the deregulation movement? Landes and Posner apply public-choice theory to the growth and character of intellectual property protection over the last half-century. The authors argue that public-choice theory alone cannot explain the coincidence of the deregulation movement and the rapid growth of intellectual property protection. Political forces and ideological currents associated with the deregulation movement, combined with interest-group pressures, best explain the increases in intellectual property protection since 1976. The authors urge caution in equating intellectual property rights to physical property rights. They counsel skeptics of government to hesitate before extending a presumption of efficiency to a process by which government grants rights to exclude competition.