In light of Elena Kagan's nomination to serve as an Associate Justice of the United States Supreme Court, this report analyzes then-Professor Kagan's views of executive power and the doctrine of separation of powers as laid most extensively out in her 2001 Harvard Law Review article Presidential Administration. This report will proceed as follows. First, it will briefly describe the constitutional and legal basis for presidential authority with respect to domestic policy, focusing on the relevant constitutional text as well as the Supreme Court jurisprudence that forms the foundation for almost all discussions of executive authority. Second, the report will provide a discussion of the well-established and competing theories of executive power, the traditional view as well as the 'unitary theory of the executive.' Third, the report will discuss Professor Kagan's theory of 'presidential administration' and her legal responses to both of the aforementioned theories. Fourth, the report will turn to the application of Professor Kagan's theory to the field of administrative law, with an emphasis on the non-delegation doctrine and the level of deference often afforded to executive branch agencies by the judiciary, often referred to as Chevron deference. Finally, the report will provide a discussion of some of the criticism of Professor Kagan's views, especially as they relate to the President's legal authority in the areas of foreign policy and national security, both of which are expected by many to be issues that the Supreme Court will adjudicate in future terms.