The third volume in the Canadian State Trials series examines Canadian legal responses to real or perceived threats to the safety and security of the state from 1840 to 1914, a period of extensive challenges associated with fundamental political and socio-economic change. Trials for treason and related political offences, suspensions of habeas corpus, and other public order and security-related measures, supported by new institutions such as secret policing, are studied in essays by leading scholars in the field. The book is divided into four parts: trials and related proceedings arising from the Fenian invasions; attempts to regulate large-scale manifestations of public disorder; trials following the North-West Rebellions of 1870 and 1885, including the Riel trial; and the modernization and enforcement of Canada's national security laws. Building upon the established scholarship of the series, the essays place these legal responses in context, shedding light on the complex and changing relationship between law and politics in Canadian history.