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Affleck Greene McMurtry LLP | Barristers

David N. Vaillancourt

David N. Vaillancourt

David N. Vaillancourt

Martindale-Hubbell Preeminent

David's practice expertise focuses on all matters of Commercial and Civil Litigation, Competition and Administrative Law.

David has acted for clients in a wide range of disputes, including shareholder and partnership disputes, securities litigation, class action defence, proceedings under the Competition Act, employment law disputes, contract disputes, breach of confidence/intellectual property disputes, fidelity bond claims, and professional negligence claims.

David has appeared before all levels of court in Ontario, including the Court of Appeal for Ontario, and has also appeared before the Competition Tribunal and the Federal Court of Appeal. David has appeared as lead counsel in numerous trials, hearings, and motions. David has been successful in numerous adversarial proceedings, and also has successfully negotiated the resolution of dozens of cases.


  • Represented a Respondent in abuse of dominance proceedings before the Competition Tribunal (two hearings) and the Federal Court of Appeal. Defence of our client at the first hearing was nominated for the Global Competition Review’s 2014 “Behavioural Matter of the Year – Americas” award.
  • Acted as defence counsel in price fixing class actions.
  • Acted in securities class actions as defence counsel and also as D&O insurer monitoring counsel.
  • Represented an insurer in fidelity bond coverage litigation.
  • Represented defendants in a variety of E&O/professional liability claims across several professions including: investment advisors, lawyers, auditors, and insurance brokers.
  • Represented defendant directors and officers being sued in a personal capacity.
  • Represented partners in acrimonious proceedings to wind down partnerships.
  • Represented employers and employees in numerous employment law cases including wrongful dismissal and payment of accrued bonuses.
  • Represented clients in commercial contractual disputes.
  • Provided advice to clients regarding Competition Act compliance and also regarding complaints to the Competition Bureau regarding competitor conduct.
  • Earned numerous law school awards, including: Middlesex Law Association Silver Medal (second highest academic standing in graduating class); Carswell Prize (top standing in International Commercial Litigation); Canada Law Book Limited Prize (top standing in Evidence); Canvasback Publishing Prize In Administrative Law; Cassels, Brock & Blackwell LLP Centennial Award In Constitutional Law.

View David's most recent publications.

Practice Areas

  • Corporate and Commercial Litigation
  • Competition Law
  • Class Action Litigation
  • Insurance Defence
  • Securities Litigation
  • Shareholder & Partnership Disputes
  • Regulatory and Administrative Law

Other Practice Areas

Show More Practice Areas
  • Breach of Confidence/Intellectual Property Disputes
  • Civil Fraud Cases
  • Civil Litigation
  • Contract Disputes
  • Employment Law Disputes
  • Fidelity Bond Claims
  • Professional Negligence Claims (lawyers, investment advisors, auditors, insurance brokers)


  • Partner, Affleck Greene McMurtry LLP 2017-present
  • Associate, Affleck Greene McMurtry LLP 2009-2016
  • Called to the Bar, Ontario, 2009
  • Articles, McCarthy Tétrault LLP 2008-2009
  • Summer Law Student, Province of Ontario, Ministry of Government Services 2007


  • Bachelor of Laws (with Distinction), University of Western Ontario, Faculty of Law (2008)
  • Bachelor of Arts in Philosophy (Hons.), University of Western Ontario, Faculty of Arts (2003

Memberships & Associations

  • Member of the Canadian Bar Association
  • Member of the Ontario Bar Association
  • Member of The Advocates’ Society
  • Vice-Chair, Reviewable Matters/Unilateral Conduct Committee, National Competition Law Section of the Canadian Bar Association