In Canada, England, and Wales, certain convicted persons may be designated as dangerous offenders and subject to a longer, or indefinite, term of imprisonment in order to protect the public. Other countries, including parts of the United States have similar provisions of law.
Worldwide.
United States.
In the United States, "Dangerous offender" statutes are defined on a state-by-state basis and are applied at sentencing such that the enhanced "dangerous offender" sentence stems from the original illegal activity. A person under "dangerous offender" sentencing is typically held for a minimum term that coincides with the sentence the person would have received without the "dangerous offender" sentence, and thereafter is subject to review of the person's state of mind as a determination of eligibility for release.
Alternatively, a person can be civilly committed if a judicial hearing determines that a concurrent mental disorder makes the person likely to remain dangerous because of a lack of self-control. This issue arose in the case of sex offenders in Kansas v Hendricks (1997) in which the court did allow limited commitment; the court reversed itself on the very same issue in Kansas v Crane (2002) imposing much stricter commitment standards and a higher burden of proof. Various state and federal sex offender registry laws impose additional post-conviction requirements for sex offenders.
Canada.
In Canadian criminal law, a convicted person who is designated a dangerous offender may be subjected to an indeterminate prison sentence, whether or not the crime carries a life sentence. This does not apply to convictions of first degree murder, second degree murder, high treason, and treason. The purpose of the legislation is to detain offenders who are deemed too dangerous to be released into society because of their violent tendencies, but whose sentences would not necessarily keep them incarcerated under other legislation, such as the Correctional and Conditional Release Act. Under subsection 761(1) of the Criminal Code, the Parole Board of Canada is required to review the case of an offender with a dangerous offender label after seven years, and parole may be granted as circumstances warrant, but the offender would remain under supervision indefinitely. After the initial review, the Parole Board must conduct subsequent reviews every two years. According to Corrections Canada, on average 24 dangerous offenders are admitted to the Canadian prison system each year. Paul Bernardo is one well-known dangerous offender.
