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Colin Johnston listen


Colin* is a strategic thinker. That’s good for his clients, who he represents in litigation relating to public and administrative law, healthcare, and professional regulation. Colin has appeared in all levels of court in Ontario, as well as many administrative tribunals and arbitration bodies. Colin brings§ a diverse range of experience to his practice. Having served as a prosecutor at the College of Physicians and Surgeons of Ontario, Colin has an inside understanding of professional regulation. He previously practiced at another prominent Bay Street law firm, representing clients in complex commercial and regulatory cases. Colin regularly speaks at educational events on issues in healthcare law, trial advocacy, and professional regulation. His experience gives clients perspective on complex legal challenges. When professionals face multiple obstacles and significant stress, Colin helps his clients see past their immediate difficulties. He brings a long-term view, working to develop a strategy to protect clients’ personal and professional interests. .


  • Practice Areas:
  • Bar Admissions:
    • Ontario (2003)
  • Education:
    • University College London (2016) LLM (Distinction)
    • Dalhousie University (2002) LLB
    • Dalhousie University (1999) MA (Philosophy)
    • Trent University (1997) BA (Philosophy) (Honours)


Colin Johnston

is a partner at Lenczner Slaght.

Colin's litigation practice focuses on healthcare litigation and administrative law. He has appeared as counsel before all levels of court in Ontario and in hearings before various administrative tribunals. Colin regularly represents professionals in civil and regulatory proceedings. He is a trusted advisor on issues in healthcare law, including medical assistance in dying, mental health law, hospital governance, medical malpractice, and professional regulation.

From 2009 to 2014, Colin was counsel to the College of Physicians and Surgeons of Ontario, where he appeared as lead counsel in numerous hearings before the College’s Discipline and Fitness to Practise Committees. He previously practiced litigation at a large national law firm in Toronto, representing clients in complex commercial and regulatory disputes.

  • Songbird Life Science Inc v Hyris Limited

    Counsel to Hyris Limited, resisting an application before the Superior Court of Justice seeking injunctive relief. The application related to Canadian distribution of Hyris’s proprietary, COVID-19-specific diagnostic technology, which permitted users to conduct accurate COVID-19 testing “on site”, without the need for a medical laboratory.

    Lawrence E. Thacker, Colin Johnston & Jim Lepore | January 1, 2022

  • Edem v Kantor

    Counsel to the successful Respondent physician in a Mental Health Act appeal concerning findings of incapacity and the issuance of a Community Treatment Order.

    Colin Johnston | January 1, 2021

  • Dhawan v Shails et al

    Successful appeal on behalf of two defendant shareholders from an order holding them liable for the debts of a company pursuant to a personal guarantee. Summary judgment was overturned on appeal. The Court dismissed the plaintiff’s claim under the guarantee.

    Colin Johnston | January 1, 2019

  • Bozzo v Giampaolo

    Counsel for the successful Respondent in an appeal concerning the dissolution of a real estate investment joint venture. Significant trial judgment upheld. (Prior to joining Lenczner Slaght)

    Colin Johnston | January 1, 2000

  • Ontario (College of Physicians and Surgeons of Ontario) v Kitakufe

    Lead CPSO prosecutor in a professional discipline case pertaining to OHIP fraud and drug trafficking. (Prior to joining Lenczner Slaght)

    Colin Johnston | January 1, 2000

  • McCarthy Corporation PLC v KPMG LLP

    Represented the Defendant in a complex auditor liability case, including five successful motions striking out the Statement of Claim as failing to disclose a reasonable cause of action. (Prior to joining Lenczner Slaght)

    Colin Johnston | January 1, 2000

  • Rudinskas v College of Physicians and Surgeons of Ontario

    Lead counsel for the Respondent regulator in a judicial review/appeal proceeding concerning the application of jurisdictional error and doctrine of prematurity in appeals under the Regulated Health Professions Act. (Prior to joining Lenczner Slaght)

    Colin Johnston | January 1, 2000

  • Great Atlantic & Pacific Company of Canada v Topostar (Aurora) Inc

    Counsel for the successful landlord Respondent in a leasing dispute concerning the interpretation of expansion provisions in a commercial lease. (Prior to joining Lenczner Slaght)

    Colin Johnston | January 1, 2000

  • Canadian Bar Association

  • Ontario Bar Association - Member-at-Large of the Health Law Executive

  • The Advocates' Society

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  • Best Lawyers in Canada (2019-2024)

    Health Care Law, Medical Negligence

  • Canadian Legal Lexpert® Directory (2021-2024)

    Medical Negligence, Professional Liability

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