Expertise
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Practice Areas:
- Bar Admissions:
- Education:
- University College London (2016) LLM (Distinction)
- Dalhousie University (2002) LLB
- Dalhousie University (1999) MA (Philosophy)
- Trent University (1997) BA (Philosophy) (Honours)
Details
- Bio
- Cases
- Associations
- Blog Posts
- News & Media
- Publications & Presentations
- Recognition
Colin Johnston
is a partner at Lenczner Slaght.
"Colin is smart, reliable, and has a wealth of experience across health law regulatory matters." — Chambers Canada
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.
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Golshahi v Northgate Medical Centre
Counsel to the defendant clinic in successfully defending a proceeding before the Human Rights Tribunal of Ontario involving claims of discrimination.
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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.
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Counsel to the successful Respondent physician in a Mental Health Act appeal concerning findings of incapacity and the issuance of a Community Treatment Order.
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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.
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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)
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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)
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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)
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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)
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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)
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Canadian Bar Association - Member-at-Large, Health Law Executive (2026-2027)
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Ontario Bar Association - Member-at-Large, Health Law Executive (2024-2027)
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The Advocates' Society
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When a healthcare professional is faced with revocation of their hospital privileges, the consequences can be significant. Many specialties depend upon systems, infrastructure, and support that can be found only within a hospital environment. A professional’s loss of their privileges may therefore effectively prevent them from sustaining their practice. Legal proceedings, including applications for judicial review, can often ensue.
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No Notice, No Dice: Divisional Court Reiterates Need for Proper Notice of Case Against
A recent Divisional Court case involving the College of Physicians and Surgeons of Ontario reaffirms the importance of ensuring that findings of professional misconduct by the College’s Discipline Committee fairly arise from the allegations contained in the College’s Notice of Hearing.
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In Horri v The College of Physicians and Surgeons, the Divisional Court reaffirms the importance of consistency and justification when a professional regulator sanctions one of its members. Penalties for misconduct should fall within the range established by previous case law, and regulators should exercise caution before departing from precedent on the basis of “changing social values.”
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Rohringer v. RCDSO: revisiting the test for interim orders against health professionals
Effective May 30, 2017, professional regulators under the Regulated Health Professions Act received a new power to temporarily restrict or suspend the licence of a health professional during the course of an investigation into allegations of misconduct or incompetence. Previously, regulators could impose such measures only after the conclusion of an investigation and commencement of a Discipline Committee proceeding. This raises the question, what is the appropriate threshold of risk that must be established in order to suspend or restrict the licence of a professional whose case is still under investigation? What evidence is required? What reasons must be given in order to justify such an order? These questions are considered in the recent decision of Rohringer v Royal College of Dental Surgeons of Ontario 2017 ONSC 6656.
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49 Lenczner Slaght Litigators Named in Best Lawyers in Canada 2027
In the 2027 edition of Best Lawyers in Canada, 49 of our expert litigators earned 172 rankings across 26 practice areas, a testament to the depth and breadth of our advocacy.
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Lenczner Slaght Celebrates 25 Years on the Lexpert Bull’s-Eye
The 2026 Canadian Legal Lexpert Directory continues to recognize Lenczner Slaght as the #1 firm in Toronto for Litigation and Commercial Litigation.
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Lenczner Slaght Litigators Featured Among Best Lawyers in Canada
The 2026 edition of Best Lawyers in Canada recognizes Lenczner Slaght with 180+ rankings, featuring 48 of our expert litigators across 27 practice areas.
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2025 Lexpert Directory Highlights Lenczner Slaght’s Excellence in Advocacy
Peers and senior members of the legal profession across the country continue to recognize the depth and breadth of Canada’s leading litigation firm in the latest 2025 Canadian Legal Lexpert Directory.
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Lenczner Slaght Litigators Recognized as the Best Lawyers in Canada
In the 2025 edition of Best Lawyers in Canada, Lenczner Slaght is proud to receive 168 total rankings, with 45 of our expert litigators recognized for their expertise across 25 practice areas.
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The 2024 Lexpert Directory Recognizes Lenczner Slaght’s Litigation Excellence
Lenczner Slaght’s litigators continue to be recognized by their peers as the foremost practitioners in their fields.
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Lenczner Slaght Litigators Recognized as Best Lawyers in Canada
In the latest edition of Best Lawyers in Canada, 41 of our expert litigators are recognized for their expertise across 24 practice areas. The following lawyers have also been recognized as “Lawyer of the Year” for receiving the highest overall peer-feedback in their practice areas in Toronto.
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Lenczner Slaght’s Litigation Excellence Recognized in 2023 Lexpert Directory
Following comprehensive peer review surveys and interviews with senior members in the legal profession, the 2023 Canadian Legal Lexpert Directory has recognized 31 of the firm’s expert litigators for their experience, knowledge, and precision, with 108 rankings spanning 17 practice areas.
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Lenczner Slaght Congratulates New Partners Colin Johnston and Sarah Millar
Canada’s leading litigation firm is proud to welcome two of our exceptional lawyers, Colin Johnston and Sarah Millar, to the partnership. Both are committed to the same excellence in advocacy that has made us Canada’s leading litigation firm.
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Lenczner Slaght Litigators Recognized Among the Best Lawyers in Canada
In the latest edition of Best Lawyers in Canada, 39 of our expert litigators are recognized by their peers for their expertise across 24 practice areas.
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2025 Snapshot: Through the Lens of Lenczner Slaght
We’ve released our 2025 Snapshot, highlighting the most significant developments, decisions, and trends in litigation from the past year across 21 practice areas. Reflect on 2025 and look ahead to 2026 through the lens of our expert litigators.
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Ontario Legal Conference: Administrative, Professional Regulation, and Immigration Law
Colin Johnston was invited to share his expertise on the panel, Recent Developments in Standard of Review for Regulated Professionals, at the program, Ontario Legal Conference: Administrative, Professional Regulation, and Immigration Law, hosted by the Ontario Bar Association. Colin discussed recent developments in the standard of review for regulated professionals, with a focus on errors of fact, law or mixed fact and law, errors in principle, and procedural fairness.
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Colin Johnston was invited to share his expertise at OsgoodePD's certificate program on Professional Regulation and Discipline in the Health Care Sector. Colin was a panelist on Module 5: Penalty Hearings and Appeals where he discussed discipline cases at the courts.
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Regulation of Healthcare Professionals: Current Trends and Emerging Issues in Law and Practice
Colin Johnston was invited to co-chair the Ontario Bar Association program, Regulation Of Healthcare Professionals: Current Trends And Emerging Issues In Law And Practice. The program covered recent developments affecting the regulation of health professionals and the legal practice. This includes the use of AI in healthcare and advocacy, regulation of political and public speech by healthcare professionals, and key updates in professional discipline proceedings.
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2024 Snapshot: Through the Lens of Lenczner Slaght
Lenczner Slaght launches our 2024 Snapshot, which highlights the most significant developments, decisions, and trends in litigation from the past year across 20 areas of expertise. Reflect on 2024 and look ahead to 2025 through the lens of our expert litigators.
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Division of Endocrinology Professional Development Day 2024
Colin Johnston was invited to speak at the University of Toronto’s Division of Endocrinology Professional Development Day 2024. Colin participated in a panel on CPSO Complaints.
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2023 Snapshot: Through the Lens of Lenczner Slaght
Lenczner Slaght launches our 2023 Snapshot, a look at the most significant developments, decisions, business takeaways, and trends in litigation from the last year, across 15 practice areas. Revisit 2023 and look ahead to 2024 through the lens of our expert litigators.
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Colin Johnston was invited to share his expertise at OsgoodePD's certificate program on Professional Regulation and Discipline in the Ontario Health Care Sector. Colin presented on Module 4: The Discipline Hearing.
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21st Annual Current Issues in Employment Law
Colin Johnston will present at the OBA's 21st Annual Current Issues in Employment Law, an essential program for staying up to date on the latest developments in employment law. Colin will share his expertise on the panel Best Practices for Conducting Workplace Investigations.
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Prosecuting and Defending Professional Discipline Cases 2023
Jaan Lilles and Colin Johnston were invited to share their expertise at OsgoodePD's annual program on professional discipline hearings. Jaan discussed Assessing Duties and Powers while Colin presented on Examinations, Interviews, Inquiries.
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Best Lawyers in Canada (2019-2027)
Health Care Law, Medical Negligence
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Canadian Legal Lexpert® Directory (2021-2026)
Medical Negligence, Professional Liability
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Lexpert Special Edition: Canada's Leading Health Sciences Lawyers (2025-2026)