Eileen McMahon

Eileen M. McMahon

Toronto: 416.865.7676
Fax 416.865.7380


BSc (Biochemistry and Chemistry), 1982
University of Toronto
LLB, 1985
Osgoode Hall Law School

Bar Admissions

Ontario, 1987


Eileen McMahon is the chair of Torys' Intellectual Property and Food and Drug Regulatory Practices. She practices exclusively in the areas of intellectual property and food and drug regulatory law. She is one of a handful of Canadian lawyers who advise on regulatory clearance and intellectual property protection of products. Eileen is a registered patent and trademark agent in the United States and Canada.

Eileen's experience includes strategic advice on identifying intellectual property and regulatory assets; obtaining and maintaining market exclusivity using intellectual property and regulatory laws; exploiting intellectual property assets; and enforcing intellectual property rights.

Eileen is also a Certified Licensing Professional of the Licensing Executive Society (LES) (2011-2014), United States and Canada. This certification is issued only to persons who have met the requirements for licensing professionals, established by CLP, Inc., under the guidance of the LES. Fewer than 1% of all attorneys have this certification.


Chambers Canada—Leading lawyer in agribusiness: agriculture & food products; cannabis law; intellectual property; life sciences: regulatory/compliance (2016-2021)

Chambers Global—Leading lawyer in intellectual property (2008-2021)

The Legal 500 Canada—Leading lawyer in intellectual property (2015-2021)

IAM Patent 1000: The World’s Leading Patent Practitioners—Leading lawyer in transactions and prosecution (2012-2021)

Managing IP’s IP Stars (Patent star, Trademark star) (2019-2021)

Managing IP’s IP Stars Top 250 Women in IP (2017-2021)

LMG Life Sciences—Life Sciences Star in intellectual property and regulatory (2012-2020)

Best Lawyers in Canada—Leading lawyer in biotechnology law, cannabis law, intellectual property law (2006-2021)

The Canadian Legal Lexpert Directory—Leading lawyer in biotechnology, intellectual property (2008-2021); technology transactions (2018-2020). Eileen is the only lawyer ranked as “Most Frequently Recommended” (Lexpert’s highest category) in Biotechnology in 2020-2021. 

Best Lawyers in Canada—Lawyer of the Year in Toronto for Cannabis Law (2020); Biotechnology Law (2016, 2010)

Who’s Who Legal—Global Elite Thought Leader in life sciences regulatory (a recognition given to fewer than 5% of all lawyers ranked by Who’s Who Legal) (2008-2021), Leading lawyer in patents (2012-2020)

Lexpert/American Lawyer’s Guide to the Leading 500 Lawyers in Canada—Leading practitioner in biotechnology law (2007-2019)

Lexpert’s Guide to US/Canada Cross-Border Lawyers in Canada—Most Frequently Recommended lawyer in IP and media (2018), business issues (2019)

LMG Americas Women in Business Law—Best in Life Sciences (2019)

LMG Life Sciences Canadian Patent Non-Contentious Attorney of the Year (2018)

IAM Licensing 250: The World’s Leading Patent and Technology Licensing Lawyers—Leading lawyer globally (2010-2017)

Lexpert/Thomson Canada’s Guide to the Top 100 Industry Specialists in Canada—Leading lawyer in pharmaceuticals and in biotechnology law (2006, 2016-2017)

Martindale-Hubbell’s Bar Register of Preeminent Women Lawyers—Highest possible rating in both legal ability and ethical standards from her peers (Martindale-Hubbell recognizes fewer than 5% of women lawyers with this preeminent rating) (2011-2013)

Which Lawyer?—Recommended Canadian practitioner in life sciences: regulatory and intellectual property (2010-2012)

Globe Business Publishing’s World Trademark Review—Recommended Canadian expert in trademarks (2009-2011)

Which Lawyer?—Highly recommended Canadian practitioner in intellectual property law: litigation (and in the Cross-Border Intellectual Property Handbook 2008/07); highly recommended life sciences practitioner in regulatory matters and in intellectual property (2008-2009)

Practical Law Company’s Cross-border Life Sciences Handbook—Highly recommended practitioner in life sciences (2007-2008) 

Women’s Executive Network—One of Canada’s 100 Most Powerful Women (2005)

Martindale-Hubbell’s Peer Review Ratings AV Preeminent Rated Lawyer—Exemplary ethical standards and legal ability



Professional Involvement

Eileen is a co-leader of a healthcare licensing course accredited by the Canadian Healthcare Licensing Association and endorsed by the Toronto Biotechnology Initiative on licensing and strategic alliances in the healthcare industry.

As one of Canada's Top 100 Most Powerful Women (Women's Executive Network), Eileen participates in the Wisdom II Mentoring Program. This program matches Canada's Top 100 award winners with young women from across Canada for mentoring.

Memberships and Affiliations

Intellectual Property Institute of Canada
Intellectual Property Owners Association
Food and Drug Law Institute
American Intellectual Property Law Association
Licensing Executives Society