Tegan O’Brien


 | Toronto

Tegan O’Brien (she/her/hers) is an associate in the Litigation Group at Cassels and a member of the firm’s Competition & Foreign Investment and Regulatory Groups.  She advises clients on all aspects of Canadian competition and foreign investment review law, including mergers & acquisitions, cartels and other criminal matters, private actions (including class actions), advertising and marketing practices, abuse of dominance and other reviewable trade practices.

Tegan has advised international and Canadian clients in a variety of industries, including mining, oil and gas, food, real estate, insurance, financial services. manufacturing and others, on merger and foreign investment reviews issues.  Her competition litigation experience includes defending domestic and cross-border class actions alleging anti-competitive conduct, including the Canadian generics price fixing class action, which has been described as involving “the largest [alleged] private sector corporate cartel in history.” Tegan also assists in other litigation matters with a focus class actions and product liability cases.

Tegan advises leading consumer products, food and drugs, medical devices, cosmetics, alcohol and cannabis clients on complex regulatory matters, including licensing, safety standards, and packaging and labelling requirements.

She is a member of the Executive of the Antitrust Law Committee of the ABA Business Law Section and an active member of both the CBA National Competition Law Section and the ABA Section of Antitrust Law. Tegan is also a co-editor of Cassels on Competition, the firm’s monthly client update on key trends and developments in Canadian competition and foreign investment law.

  • J.D., University of Toronto, 2017
  • B.A.Sc. (Honours) (with Distinction), McMaster University, 2014
  • Ontario, 2018