Special Investigations Unit (Ontario)

The Special Investigations Unit (SIU, or "the Unit"; French: Unité des enquêtes spéciales, UES) is the civilian police oversight agency of the province of Ontario, Canada. The SIU is responsible for investigating circumstances involving police that have resulted in a death or serious injury, or if a firearm was discharged at a person. The unit also investigates allegations of sexual assault. The unit's goal is to ensure that criminal law is applied appropriately to police conduct, as determined through independent investigations, increasing public confidence in the police services.

The director is responsible to the Attorney General of Ontario, and the unit as an "arm's-length" agency of the Ministry of the Attorney General. The current director is Joseph Martino; he initially served in an acting capacity from April 2019 prior to his formal appointment in November 2019.