Josh Chafetz‘s new book, Congress’s Constitution: Legislative Authority and the Separation of Powers (Yale University Press, 2017), examines Congress as a branch and the powers of the legislature within the constitutional system. This book approaches the Legislative branch historically, constitutionally, politically, and structurally the separation of powers. Chafetz situates Congress as one of three political branches of government, each deriving power from the public, the constitution, formal responsibilities (like the Senates role in confirmation, or Congress’s power of the purse), and also informal capacities. In analyzing Congress, Chafetz makes use of the schematic framework of hard and soft power, often used by scholars to analyze international relations, contextualizing the kinds of powers that Congress has and how those powers have been used over the history of the branch and continue to be used. Chafetz explains his thesis in regard to the separation of powers theories as a multiplicity based understanding of the claims made to authority not only by Congress, but also by the Executive and Judicial branches, noting that there are multiple and overlapping claims to authority. The book will be of interest to a range of scholars and readers, since Chafetz integrates American political development, constitutional history, contemporary American politics, and the complexity of the development of British legislative authority that preceded and contributed to the American constitutional system. This is an accessible, complex, and fascinating book about American politics, the constitutional system, and, especially legislative authority within the system.