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This is a photo of Leah Ostler




Contact by email at [email protected]

t. +1 416-601-8285


An experienced and passionate litigator, Leah places her clients’ needs at the centre of every matter and fiercely advocates for their best interests.

Leah is an associate in our Litigation Group in Toronto. Her practice focuses on defence litigation, including commercial matters (specializing in accounting and pensions matters) and professional negligence. She has served as counsel in motions, applications, trials and class actions, and as lead counsel before courts and administrative tribunals in a wide range of complex matters.

Leah’s notable engagements include:

  • Representing public corporations in pension class actions, including by defeating jurisdiction motions before the regulatory tribunal (FST) and Superior Court, ultimately certifying the defendants’ class proceeding: Brewers Retail v. Campbell, 2022 ONSC 2795; appeal dismissed, Brewers Retail v. Campbell, 2023 ONCA 534. 
  • Representing the Toronto-Dominion Bank in a timely and novel interpleader application: Li et al. v. Barber et. al., 2022 ONSC 1543;
  • Representing Bell Canada in a hotly contested injunction with another telecommunications company, which included a parallel regulatory application;
  • Representing financial institutions in multi-million dollar securities class actions;
  • Representing professional accounting firms in civil and regulatory proceedings;
  • Representing a university in a complex construction negligence matter;
  • Representing physicians in civil liability motions and trials in multiple levels of Court, applications before and appeals of the Consent and Capacity Board, and regulatory proceedings before the CPSO, HPARB and appeals to the Court;
  • Lu v. Kalman, September-October 2023: First chair in the defence of several physicians in a medical negligence trial, decision pending. Successfully argued several in-trial motions with published decisions: Lu v. Kalman, 2023 ONSC 5335; 2023 ONSC 5912.
  • Carroccia v. Ayow, October 2020: Second chair in the successful defence of a physician in a medical negligence jury trial – the first civil jury trial conducted in Ontario under COVID-19 protocols.
  • McKitty v. Hayani, 2019 ONCA 805: Second chair in the successful defence and response to appeal in the leading Canadian case on the legal definition of death.

Leah brings a pragmatic approach to risk management to advise clients on accounting and pension matters and represent them in litigation.

Leah obtained her Certificate in Pensions Law through the Osgoode Professional Development Office in 2023. Leah is a member of the Pensions & Benefits Section of the Ontario Bar Association and the Ontario Regional Council of the Canadian Pension and Benefits Institute. She presented on legal and governance insights for pension litigators at McCarthy Tétrault’s 12th and 13th Annual Pension & Benefits Seminars. 

Leah stays on top of industry trends in the accounting industry, offering novel advice and solutions to civil litigation and regulatory proceedings. Leah coordinates nationally-held CPD sessions for Accounting Firms on a wide range of cutting-edge issues. 

Leah received her J.D. from Osgoode Hall Law School, where she held executive positions with the Osgoode Women’s Network (OWN), was a Dean’s Fellow for Torts Law, and led several mentorship programs. Leah did a semester abroad at Amsterdam University, where she took Masters of Laws courses in International Law. Leah obtained her B.A. (Honours) in History and Global Development from Western University and was later a Political Intern for the Department of Foreign Affairs and International Trade (DFAIT) in the Middle East.