The years 1918-1925 were the most turbulent in recent Irish history, a time of momentous constitutional change and widespread political unrest. Faced with armed insurrection and revolutionary claims to democratic legitimacy, the British government responded with increasingly harsh emergency powers. These measures provided the model for the governments which emerged following the partition of the country into the Irish Free State and Northern Ireland. In this scholarly and compelling book Dr Colm Cambell offers a detailed legal analysis of emergency powers and assesses their impact upon the outcome of political conflicts. Drawing upon extensive archival materials, the author examines the effect of emergency law on the battle for legitimacy in three jurisdictions: Ireland under British rule 1918-1921; the Irish Free State 1922-25; and Northern Ireland 1921-25. By identifying and discussing three core areas of emergency law in all three jurisdictions, such as special powers of arrest and detention, special courts and internment without trial, the author brings out the historical continuity in the development of these powers. The role of the judiciary in co-operating with laws which helped to marginalize them is also discussed. Carefully researched and cogently argued, this book will appeal not only to historians but also to constitutional lawyers, political scientists, and scholars interested in civil liberaties and the history of laws relating to political violence.