A dangerous offender designation is the most severe sentence available in Canadian criminal law. Under Part XXIV of the Criminal Code (sections 752–761), the Crown can apply to have an offender designated as a dangerous offender after conviction for a "serious personal injury offence" — a category that includes violent and sexual offences carrying a maximum sentence of 10 years or more.
To obtain the designation, the Crown must prove that the offender constitutes a threat to the life, safety, or physical or mental well-being of others based on a pattern of repetitive behaviour, a pattern of persistent aggressive behaviour, or conduct of such a brutal nature that ordinary standards of restraint will not control the offender. The court will consider psychiatric evidence and the offender's criminal history.
If designated a dangerous offender, the court must impose an indeterminate sentence of imprisonment — meaning the offender will remain in custody indefinitely, with periodic parole reviews but no guaranteed release date. The court may instead impose a long-term offender designation (up to 10 years of community supervision after the prison sentence) if that would adequately protect the public.