In this essay, Christopher Coyne reviews Rise of the Warrior Cop: The Militarization of America's Police Force by Radley Balko. For over a decade, Radley Balko, a journalist and blogger, has been documenting the disturbing trend of police militarization across America. In the process, he has repeatedly raised concerns about the implications of this trend for the freedoms and liberties of U.S. citizens. Rise of the Warrior Cop can be seen as a culmination of Balko's research on the topic. It provides a well-researched, yet very readable, history of the changing role of police in the United States and documents the factors influencing the trajectory toward increased militarization.