This treatise provides a comprehensively updated analysis of administrative law in the United States, placing special emphasis on topics undergoing significant evolution or transformation in the Supreme Court and federal courts of appeals. These include, for example, the latest developments in Congress's authority to delegate legislative authority to agencies, deference to agency legal interpretations, the so-called major questions doctrine, modern due process issues, and the presidential appointments power. The fundamental purposes of this book are to assess and explain the current state of the core doctrines of administrative law, place the most important aspects of those doctrines in a historical context, and identify important trends that can help readers understand how the doctrines may continue to evolve. The book is intended to serve practitioners, scholars, and students of administrative law.