This book examines the royal prerogative in terms of its theory, history and application today. The work explores the development of the royal prerogative through the evolution of imperial government, and more recent structural changes in the United Kingdom and elsewhere in the Commonwealth. While examining specific prerogative powers, the development of justiciability of the prerogative, and the exercise of the prerogative, it lays bare the heart of constitutionality in the Westminster system of government. There is said to be a black hole of unaccountable authority at the heart of the constitution and it is this which this book examines. The focus is upon the constitutional development of the United Kingdom and the old dominions of Canada, Australia and New Zealand. This approach is comparative and historical, using specific case studies of such events as the dissolution of Parliament and the appointment and dismissal of Prime Ministers. The book will be of interest to academics and researchers working in the areas of Constitutional Law and Politics.