Administrative Law explains the constitutional principles of the subject. It brings clarity to this complex field of public law. The common law courts, government agencies, and Parliament have developed a wide variety of techniques for controlling the enormously diverse activities of twenty-first century government. Underlying all that variety is a set of constitutional principles. This book uses the law of judicial review to identify and to explain these principles, and then shows how they ought to be worked out in the private law of tort and contract, in the new Tribunals Service, and in non-judicial techniques such as investigations by ombudsmen, auditors, and other government agencies. The aim is to equip the reader to apply the constitutional principles to the problems of administrative law.