The Introduction provides an overview of the history of the writ of habeas corpus and an overview of the book, which tells the story of what is sometimes known as “the Great Writ” as it has unfolded in Anglo-American law. The primary jurisdictions explored are Great Britain and the United States, yet many aspects of this story will ring familiar to those in other countries with a robust habeas tradition. The book chronicles the longstanding role of the common law writ of habeas corpus as a vehicle for reviewing detentions for conformity with underlying law, as well as the profound influence of the English Habeas Corpus Act of 1679 on Anglo-American law. The Introduction highlights how the writ has at times failed to live up to its glorification by Blackstone and others, while noting that at other times it has proven invaluable to protection of liberty, including as a vehicle for freeing slaves and persons confined solely based on a King’s whim.