In any society, certain people pose a risk to others. For hundreds of years, preventive detention has been authorized by governments to ensure people are held in custody for: criminal proceedings, mental health issues, quarantine, inebriation, enemy alien status, sexual predator suspicion, etc. The policy has also been famously employed more recently to control suspected terrorists. In all of these areas, governments need to balance the protection of the community with the rights of the "dangerous" person. These regimes have proliferated in recent years, and this book asks and answers some of the fundamental questions about these regimes: What are their doctrinal foundations? * Is there a risk in laws that blur the historic division between criminal and civil law, allowing civil law to be used for criminal law purposes, but without the protection normally provided to criminal defendants? * Are they effective in protecting people from harm? * How do these regimes challenge fundamental principles, such as human rights? * What are the remedies available to people who seek to challenge these regimes? Regimes that punish people who have not been convicted of a fresh crime or that contemplate the infliction of punishment upon breach of a "control order" require careful scrutiny to avoid human rights abuse. The book considers preventive detention in its many varying forms across Europe, the Americas, and Australasia. It interrogates the theoretical underpinnings of these regimes and then critically analyzes these for consistency with international human rights. Preventive Detention: Asking the Fundamental Questions brings together respected international experts to guide lawmakers, policymakers, and academics in an increasingly significant area of penal and public policy.