Olivier Therrien

Olivier Therrien is a partner in Gowling WLG's Montréal office, practising primarily in the area of commercial litigation. His practice focuses on complex commercial disputes involving various topics, with a focus on construction disputes, professional liability (engineers, geologists, architects, etc.) and contaminated sites. In addition to traditional litigation services, his clients appreciate his business-oriented approach and legal advice aimed at managing and mitigating litigation risks.

Olivier has been involved in complex litigation matters, including class actions and mass tort litigation. A recent example of Olivier's approach to complex litigation and recent success is discussed here. His practice currently focuses on manufacturer's, professional and builder's liability as well as environmental law, with a particular focus on contaminated sites.

His environmental law practice includes litigation, legal advice, regulatory work and risk management in connection with spill incidents, historical contamination, sale of contaminated sites, decommissioning and remediation obligations, change of use, brownfield redevelopments, as well as related real estate issues.

Olivier also practises in the following fields: general civil liability, consumer protection, franchise and distribution, competition law, trademarks, injunctions, and extraordinary recourses.

Olivier has had extensive experience appearing before most courts and has been involved in long trials.

His clients appreciate his skills as a trial lawyer (cross-examination, traditional and electronic discoveries, investigation, document management, management of expert evidence) as well as his negotiating skills when it comes to resolving litigation outside of court.

Olivier practises in English and French. He also speaks conversational Spanish.

Career & Recognition

Filter timeline:
  • 1999

    • Qualifications (Year of Call/Admission, etc.)
      Year of Call, Quebec
  • 1998

    • Education
      Osgoode Hall Law School, LLB
  • 1997

    • Education
      Québec Bar, vocational training
  • 1996

    • Education
      University of Montréal, BCL

Representative Work

Olivier Therrien has been the lead counsel defending Lafarge Canada Inc. in one of the biggest mass tort in Canada. The case involved close to 2000 concrete structures that had been allegedly damaged as a result of a chemical reaction occurring inside the concrete which had been attributed to the aggregate at issue. In a first wave of claims, SNC Lavalin Inc. was condemned to pay $220M to affected homeowners in Trois-Rivières Québec (see media coverage here). In a subsequent case, SNC Lavalin Inc. sued Lafarge Canada Inc. for contribution.

On February 4, 2021, after more than 10 years of litigation and a 50-day trial, the Superior Court of Québec rendered a judgment in the Trois-Rivières pyrrhotite cases which dismissed SNC Lavalin's allegations that Lafarge Canada Inc. and its representatives had been negligent with respect to the aggregate contained in the concrete sold by certain ready-mix companies between 2002 and 2007 (Judgement in French here and media coverage in French here). For Lafarge and its employees, who were cleared of any blame, this was a complete victory.

This success was the result of hard work and dedication by a team of professionals involved at Gowling WLG, from staff, paralegals, associates and partners.