In lively prose, Ackerman and Ginsberg explain the origins of each constitutional provision, assess the ways in which each has been used and interpreted over time, and examine the controversies that continue to surround key constitutional principles such as the president's powers during times of war and Congress's power to regulate interstate commerce. The authors also address a number of long-standing American political principles and practices that are not discussed in the Constitution, although many Americans think they are. A selection of related documents is included, as well as a list of recommended online resources for further reading and research. The Third Edition includes expanded headnotes, coverage of recent Supreme Court decisions, and other important updates.