"Peter Mantas made headlines with his representation of Nigel Wright, Chief of Staff to the Prime Minister of Canada, with respect to investigation concerning an expense scandal at the Senate"

- Benchmark Canada, the definitive guide to Canada's leading litigation firms and attorneys.

“Mantas is citing a lot, and I mean a lot, of case law to back up his arguments … Mantas is even throwing in some case law from the US, just for good measure.”

- Live courtroom Tweet by the CBC during oral argument in Guergis v. Prime Minister Stephen Harper, et al.


  • LLB, 1992
    University of Ottawa
  • BA, Trinity College, 1989
    University of Toronto

Year of Call/Admission

  • Ontario, 1994
  • New York, 1993

Peter N. Mantas

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+1 613 696 6886
+1 613 230 6423 (fax)
Lawyer LinkedIn profile
Peter Mantas is the head of the Ottawa litigation group, Co-Leader of the firm’s White Collar Defence and Investigations group and a member of the firm’s Litigation Steering Committee. He is also the Co-Chair of the Class Actions Section of the Ontario Bar Association.

An experienced litigation lawyer, Peter is valued for his careful preparation, strategic advice and tough but reasonable approach. Described as a Canadian and Ontario litigation star by Benchmark Canada, he has acted as legal counsel in some of the most prominent cases in the country.

Peter has considerable experience in matters involving a large and complex documentary record. He is an avid user and proponent of technology in the litigation process in order to reduce costs and achieve better results.

Peter practises in the following areas of litigation: corporate/commercial; class actions; proceedings against government; public procurement; competition/anti-trust; governance and ethics; fraud; defamation; franchise; and international investigations and proceedings. He has experience in both civil and criminal cases.

He has acted as counsel at the trial and appeal level before the Ontario and Federal courts, numerous Canadian provincial and territorial courts, the Supreme Court of Canada, the Canadian International Trade Tribunal, international and domestic arbitration panels.

Peter was a law student at the Paris office of U.S.-based law firm, Cleary Gottlieb Steen & Hamilton, and at the Canadian International Trade Tribunal.

Honours and Awards

  • Recognized in the 2016 and 2017 edition of Chambers Canada for Public Procurement
  • Nominated for the 2016 and 2015 Lawyer of the Year Award by Benchmark Canada for White Collar Crime/Enforcement
  • Recognized in the 2015 edition of The Legal 500 Canada for Dispute Resolution: Ontario
  • Named as national "litigation star" for white collar criminal law in the 2014 edition of Benchmark Canada.
  • Named as an Ontario "litigation star" for commercial, media/defamation, and white collar criminal law in the 2014 edition of Benchmark Canada.

Community Involvement


  • Co-Chair, 2015-16, Class Actions Section, Ontario Bar Association
  • Member, Canadian Bar Association
  • Member, Country of Carleton Law Association