"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 and co-leader of the firm’s White Collar Defence and Investigations group. He is also the past co-chair of the Class Actions Section of the Ontario Bar Association. Peter is an editor of Fasken Martineau’s white collar defense blog, White Collar Post.

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. He is frequently retained on high profile matters requiring an understanding of reputational risk and media relations, and experience in crisis management.

Peter has considerable experience in cases 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, and in judge only and jury trials.

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 as a "Litigation Star" by Benchmark Litigation for commercial, defamation, media and white collar criminal law (2017, 2016, 2015 and 2014)
  • Recognized as a "Litigation Star" by Benchmark Canada in Defamation, Commercial Litigation and Media and Entertainment in Ontario, 2017
  • Recognized in Chambers Canada for Public Procurement (2016-2018)
  • Recognized in The Legal 500 Canada for Public Procurement (Canada) (2017 and 2016)
  • Recognized by Lexpert for Litigation (Director’s & Officer’s Liability) (2017)
  • Nominated for Lawyer of the Year Award by Benchmark Canada for White Collar Crime/Enforcement (2017, 2016 and 2015)
  • Nominated in Canadian Lawyer magazine as one of the 25 most influential lawyers in Canada (2016)

Community Involvement


  • Member of the Executive 2012-17 (Co-Chair, 2015-16) Class Actions Section, Ontario Bar Association
  • Member, Canadian Bar Association
  • Member, American Bar Association
  • Member, Country of Carleton Law Association