Dennis R. O'Connor
The Honourable Dennis R. O'Connor is the Associate Chief Justice of Ontario and was Commissioner of the Walkerton Inquiry. 

Justice O'Connor graduated  from Osgoode Hall Law School in 1964, and was called to the Bar of Ontario in 1966.

He practiced law until 1973 when he was appointed Magistrate in the Yukon Territory until 1976, a position he held until 1976. From 1974 to 1976 he also served as provincial judge in British Columbia and Deputy Magistrate for the Northwest Territories. 

In 1976, he became associate professor of law at the University of Western Ontario, teaching criminal law, civil and criminal procedure and trial advocacy. In 1980 he joined the Toronto law firm of Borden, Elliot. From 1980 to 1984, he acted as the chief negotiator for the Government of Canada for the Yukon Indian Land Claim. He served two terms as an elected bencher for the Law Society of Upper Canada beginning in 1987. In 1998, he was appointed to the Ontario Court of Appeal, and in 2001 he was appointed Associate Chief Justice of Ontario.

In June 2000, Justice O'Connor was appointed by the Province of Ontario to conduct a public inquiry into the causes of the contamination of the water system in Walkerton, Ontario. He was directed to make recommendations to ensure the safety of the Province's water system and delivered two reports in 2002. 

Justice O'Connor is a member of the Canadian Judicial Council, Canadian Bar Association, the Advocates' Society and a Fellow of the American College of Trial Lawyers.