Lesley Caswell

Lesley is a partner specializing in patent clearance and validity opinions and patent litigation (both impeachment actions and actions under the Patented Medicines (Notice of Compliance) Regulations.

Lesley’s main areas of practice relate to chemistry and pharmaceutical sciences and she has extensive experience advising pharmaceutical companies with respect to intellectual property and regulatory issues.

Lesley has been involved in a number of important intellectual property litigation cases including:

  • Teva Canada Innovation and Teva Canada Limited v. Pharmascience Inc., 2020 FC 1158
  • Sanofi-Aventis Canada Inc. v. Teva Canada Limited., 2012 FC 552
  • Novopharm Limited v. Eli Lilly and Company, 2010 FC 915
  • Sanofi-Aventis Canada Inc. v. Teva Canada Limited, 2009 FC 676

Lesley is a registered Canadian patent agent. She is also a member of the Intellectual Property Institute of Canada and the American Bar Association.

Representative Work

Recent representative experience includes representing:

  • Natco Pharma (Canada) Inc. in litigation involving generic pharmaceuticals including lenalidomide, pomalidomide, ibrutinib and tenofovir alafenamide.
  • Teva Canada Limited in litigation involving both brand and generic pharmaceuticals including Copaxone, palperidone palmitate, atomoxetine, teriparatide, efinaconazole, and ramipril.

Professional Affiliations

  • Law Society of Ontario
  • College of Patent Agents and Trademark Agents
  • American Bar Association
    Intellectual Property Institute of Canada
  • Canadian Bar Association

Awards and Recognition

  • LMG Life Sciences – Recognized, Intellectual Property
  • Who’s Who Legal: IP (2023)
  • Lawyer Monthly Women in Law Awards 2021


  • Bachelor of Laws, University of Victoria (1999)
  • Honours Bachelors of Science (Chemistry), University of British Columbia (1992)

Speaking Events

  • “Taking Due Care II: Coping with CIPO’s Due Care Requirements” (moderator), IPIC Webinar, June 12, 2023
  • “Best Practices in Pharmaceutical Patents” (moderator), IPIC Webinar, September 21, 2022