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Affleck Greene McMurtry LLP | Barristers
David N. Vaillancourt

David N. Vaillancourt

David N. Vaillancourt

2024 LEXPERT-ranked Lawyer

David is a determined and committed advocate for his clients.  David has extensive courtroom experience, having successfully appeared as lead counsel in numerous trials, hearings, motions, and appeals. David is also a skillful negotiator, having successfully negotiated the resolution of dozens of cases.

David is rated as AV Preeminent by Martindale-Hubbell (the highest rating possible), with his peers at competitor law firms noting that David is an “excellent lawyer and advocate”, he is “diligent and creative in his approach”, and “is capable of taking charge in the largest commercial and insurance claims”.

David has a broad practice in commercial litigation, insurance law, and competition law.


  • Represents clients both advancing and responding to fraud claims
  • Represents clients bringing and responding to urgent injunctive relief, including Mareva injunctions
  • Represents clients in shareholder and partnership disputes
  • Represents clients in contractual disputes and other commercial disputes
  • Represents clients bringing proceedings to enforce foreign judgments in Ontario
  • Represents employers and employees in employment litigation including wrongful dismissal and payment of accrued bonuses
  • Represents insurer clients in fidelity bond coverage disputes
  • Acts in securities class actions as defence counsel and also as D&O insurer monitoring and coverage counsel
  • Represents defendants in a variety of E&O/professional liability claims across several professions including: investment advisors, lawyers, auditors, and insurance brokers
  • Represents clients in securities litigation
  • Represents clients in proceedings before the Competition Tribunal, including abuse of dominance proceedings
  • Provides advice to clients regarding Competition Act compliance and also regarding complaints to the Competition Bureau regarding competitor conduct
  • Former Chair and Vice-Chair of the Reviewable Matters/Unilateral Conduct Committee of the  Canadian Bar Association’s Competition Law section
  • Lead author of the Canadian chapter of The Private Competition Enforcement Review
  • 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
  • Member of the Professional Liability Underwriting Society