The Law of the Executive Branch: Presidential Power. By Louis Fisher. New York: Oxford University Press, 2014. 458 pp. Louis Fisher is one of the country's greatest experts in the constitutional law and politics of Congress and the presidency. For many years, he was a senior specialist at the Congressional Research Service and has frequently been called to testify on issues of institutional power. He has written nearly two dozen books analyzing various aspects of constitutional law, with a particular emphasis on separation of powers. As a consequence, he is the perfect choice to produce the first treatise in the new Oxford Commentaries on American Law series, which hopes to revive treatises as a central scholarly vehicle for synthesizing the law for scholars, students, and practitioners alike. Fisher gets the series off to a very promising start. Within the realm of treatise writing, the law of presidential power has not received its due. Even in the golden age of treatises, the presidency received only limited attention within larger works. This absence is perhaps not surprising given the relative weakness of the presidency at the turn of the twentieth century and the paucity of black-letter law delineating the executive office. The early twenty-first century is a different constitutional world, but synthetic commentaries have not caught up. As a consequence, Fisher is able to admirably fill this hole. The only close predecessors to what Fisher has offered here is Edward S. Corwin's magisterial The President: Office and Powers, first published in 1940 (New York University Press), and Peter M. Shane and Harold H. Bruff's The Law of Presidential Power: Cases and Materials, which first appeared in 1988 (Carolina Academic Press). Shane and Bruff is more of a casebook, however, with the focus on extended excerpts from key legal documents. As with Corwin, Fisher brings to this project an expertise in law combined with the eye of a political scientist, and both are crucial for analyzing the separation of powers. The purpose of a treatise of this sort is not to provide a political analysis of how presidents exercise power, but rather to elucidate the principles and content of the rules that authorize and limit presidential power, and Fisher rightfully keeps the focus on formal constitutional powers. The result is an efficient and reliable introduction to the constitutional law and powers of the presidency. Of course, Fisher is not merely an expert in the field. From his perch in the Congressional Research Service, he has long been a partisan of legislative power within the constitutional scheme and a critic of presidential overreach. In that, he is not much different than Corwin himself, who produced his treatise on the presidency just as he was turning away from the Franklin Roosevelt administration that he had once advised and was launching a critique of presidential war power. As with Corwin, Fisher has largely been able to put aside his own preferences about how the Constitution should be understood and to provide a fair description of how the constitutional rules have developed in law and practice. …