William Ian Corneil Binnie CC KC (born April 14, 1939) is a former puisne justice of the Supreme Court of Canada, serving from January 8, 1998 to October 27, 2011.

He was called to the Ontario bar in 1967 and practiced private law at Wright & McTaggart and its successor firms until 1982, at which point he was appointed Associate Deputy Minister of Justice for the Government of Canada.

[6][7] He continued until Michael Moldaver and Andromache Karakatsanis were appointed in on October 27, 2011, replacing him and Louise Charron, who had left the court on August 30, 2011.

In retirement, Binnie received various mandates including appointment by the Secretary General of the United Nations to chair the UN Internal Justice Committee (2015-2019).

David Bain, a New Zealander, had spent 13 years in prison as a result of a conviction, found to be wrongful, of murdering his father, mother and three siblings in the family home in Dunedin.

At the re-trial, following 12 weeks of testimony, much of it fresh evidence, the jury in Christchurch took only half an hour to acquit David Bain of all charges.

The findings of police ineptitude included burning down the family house where the murders occurred before any defence expert had been given the opportunity to conduct an independent investigation of the crime scene, and subsequently destroying the blood and tissue samples and other trial exhibits before the period for appeals expired.

The President of the Canadian Bar Association, Robert Brun, QC, said Binnie “is held in the highest esteem by both the legal community and the judiciary for his integrity, skill, and experience.

He is praised for his honesty and intellect, and his reputation extends well beyond Canada's borders.”[18] Minister Collins hired a former New Zealand trial judge, Robert Fisher, to criticize Binnie's report, which he did, stating that while the report was well organized and comprehensive, nevertheless in his view Binnie went beyond his mandate and authority, and had made errors in the legal tests applicable to the evidence.

[19][20] Former Australian High Court Justice Ian Callinan was then commissioned by the New Zealand Government to conduct a fresh enquiry.

[Michel Bastarache, Ce Que Je Voudrais Dire a Mes Enflants, Les Presses de l'Universite d'Ottawa 2019 at p 206].

In R v Campbell [1999] 1 SCR 565 Binnie wrote for the Court that in prosecutorial decisions the police are independent of political direction or control.