Expertise
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Practice Areas:
- Bar Admissions:
- Education:
- Queen’s University (2023) JD
- Queen’s University (2017) MA (Political Studies)
- Western University (2016) BA (Political Science)
Details
- Bio
- Cases
- Associations
- Blog Posts
- News & Media
- Publications & Presentations
Derek Hooper (he/him)
is an associate at Lenczner Slaght.
Derek is developing a broad commercial litigation practice that includes acting for complex real estate matters, partnership and shareholder disputes, securities litigation, and injunctions. He also routinely acts for clients in employment disputes and professional liability matters. Derek is the co-chair of the firm’s Pride Affinity Group, which fosters 2SLGBTQ+ visibility and community within the firm. He previously summered and articled at Lenczner Slaght.
Before joining the firm, Derek graduated from Queen’s University, Faculty of Law. While in law school, Derek worked as a Student Caseworker at the Queen’s Prison Law Clinic, as Vice President of Finance of the Queen’s Law Students’ Society, and as an Associate Editor of the Queen’s Law Journal. He was also a finalist in the Queen’s Law Litigation Society Moot. Recognized for his academic achievements in law school, Derek made the Dean’s Honour List in all three years for finishing in the top 10% of his class, and was awarded Course Prizes in both Employment Law and Legal Skills.
Prior to law school, Derek gained years of experience in the banking and securities industries. He successfully completed his Canadian Securities Course and was licensed with both MFDA and IIROC respectively. He worked as a Financial Advisor at a leading Canadian banking institution where he managed a book of high-net-worth clients. He advised on all aspects of their financial portfolios, including business banking, credit borrowing, and investment planning.
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Acted as counsel for participating parties with standing in a mandatory inquest into the death of a patient at a hospital, pursuant to section 10 of the Coroners Act.
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Robert Plamondon v Knowledge First Financial Inc
Counsel to Knowledge First Financial, a leading investment fund and RESP provider, in an action brought by a former agency director for commissions and referral fees he alleges are owed. The matter involves the tolling of limitation periods, the duty of good faith in contractual negotiations, and unjust enrichment in the context of securities commissions.
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Castillo v Xela Enterprises Ltd
Counsel to the court-appointed receiver in successfully obtaining a finding of civil contempt and a full indemnity costs award in proceedings before the Commercial List – both of which were upheld on appeal.
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Masters Insurance Limited v Ciccolini and Platform Insurance Management
Counsel to the new employer in a case alleging breaches of non-competition and non-solicitation covenants in an employment agreement with the plaintiff employer.
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1107051 Ontario Ltd v GG Kingspa Enterprises Limited Partnership
Counsel to Great Gulf, a major real estate developer, in successfully defending a large commercial litigation arising from the development of two large condominium projects in downtown Toronto, involving claims of repudiation, contested pleading amendments, and issues of settlement privilege. Great Gulf successfully resisted the Plaintiffs' motions to strike repudiation claims advanced in its counterclaim and to amend its pleadings, and was partially successful on a motion to strike portions of the Plaintiffs' claim on the basis of settlement privilege.
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The Estate of Vivian Maier v Stephen M. Bulger
Counsel to the Stephen Bulger Gallery in an action for copyright infringement in fine art photographs taken by the posthumously-discovered photographer Vivian Maier.
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Counsel to a defendant physician in a class action brought by patients who allege that the physician used a substance not approved by Health Canada in cosmetic procedures. This is the first time a certified class action has been dismissed for delay in Ontario and is now the leading decision on the dismissal for delay test.
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The Advocates’ Society
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Ontario Bar Association
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Community One - Board of Directors
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Court of Appeal Ruling Advances Funding for Gender Affirming Care
The Court of Appeal recently issued a significant decision, Ontario (Health Insurance Plan) v KS, on funding for gender affirming care. The ruling provides clarity on access to insured gender affirming procedures while leaving some questions unresolved for future consideration.
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Languishing in Langenecker? Court of Appeal Says “No More”
In Barbiero v Pollack, the Ontario Court of Appeal has departed from Langenecker v Sauve and changed the law of dismissal for delay under Rule 24.01. Where a delay is found to be both inordinate and inexcusable, that alone is sufficient to dismiss the action. Plaintiffs can no longer allow an action to languish for years and then rebut the presumption of prejudice to keep it alive.
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Contempt on the Commercial List
Court orders must be obeyed. If they are not, the consequences can be severe.
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Lexpert’s Top 10 Business Decisions of 2024–2025
Lenczner Slaght was featured in Lexpert's Top 10 Business Decisions of 2024-25 for its involvement in Barbiero v Pollack.
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Lenczner Slaght Welcomes 10 New Associates
Canada’s leading litigation firm continues to strengthen its talent pool with the addition of 10 exceptional associates.
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Lenczner Slaght Welcomes Summer Student Class of 2022
Canada’s leading litigation firm continues to attract top talent with the addition of 12 exceptional students.
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University of Toronto Faculty of Law Youth Summer Program
Derek Hooper spoke on the Litigation Panel as part of the Youth Summer Program at the University of Toronto Faculty of Law. The program offers high school students a look into law school and advanced legal topics. Derek shared his insights into litigation and what it's like to practice at Canada’s leading litigation firm.
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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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Derek Hooper, Liza Leshchynska, Christina Papageorgakopoulos, Gregory Pike, Madison MacKinnon, Rachel Rowlands, Cat Blair, and Kyle Magee served as judges at the Queen's Law Moot Society’s Cromwell Moot.
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Attend Examinations for Discovery… Or Else?
Nicole Naglie and Derek Hooper authored an article published by the Ontario Bar Association, exploring the importance of attending examinations for discovery in wrongful dismissal cases and how repeated non-compliance can lead to pleadings being struck, while isolated incidents are less likely to result in such severe outcomes.
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University of Toronto Faculty of Law's Youth Summer Program
Derek Hooper and Liza Leshchynska were invited to share their expertise at the University of Toronto Faculty of Law's Youth Summer Program. Derek and Liza joined a litigation panel to offer insights on working in litigation and the journey to becoming a lawyer.
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Mahgol Taghivand, Derek Hooper, and Madison MacKinnon served as judges at the Queen's Law Moot Society’s Inaugural Moot.
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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.