Patrick Welsh

Patrick Welsh, Associate, Litigation

Contact Information

  • tel: 416.862.5951
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Bar Admission

Ontario, 2011


  • Queen’s University, J.D.
  • Queen’s University, M.A. (History)
  • Queen’s University, B.A. (Hons.) (with distinction) (Biology and History)






Patrick is a member of Osler’s Litigation Department, with a focus on environmental law and litigation and environmental due diligence.

Patrick has experience in issues relating to waste diversion, transportation of dangerous goods and hazardous wastes, emissions and discharges, contaminated lands, maritime pollution and spills, regulatory orders, waste and soil, and general environmental regulatory compliance.  He has also provided transactional support on environmental issues arising during mergers and acquisitions, and debt and equity offerings.

On the litigation, advocacy and dispute resolution side of his practice, Patrick has experience in contaminated lands litigation, negligence, administrative hearings, judicial reviews, procurement challenges, and international anti-corruption investigations.

Patrick has appeared before the Ontario Environmental Review Tribunal, the Ontario Energy Board, the Ontario Superior Court (Commercial List), the Ontario Court of Appeal, and the Federal Court of Canada.

In his undergraduate studies at Queen’s, Patrick majored in biology and history.  His M.A. studies included a course on environmental history. Patrick was also actively involved in student government, and in 2010, he was recognized with the Agnes Benidickson Tricolour Award for valuable and distinguished service to Queen’s University.

Patrick joined the firm as a summer student in 2009 and articled with the firm in 2010-2011, during which time he was seconded to the legal department of the Royal Bank of Canada.


  • The Advocates’ Society
  • Canadian Bar Association
  • Law Society of Upper Canada
  • Ontario Bar Association
  • The Osgoode Society for Legal History

Industry Recognition

  • Gavel Award (2010)
  • John D.B. Walton Scholarship in Administrative Law (2010)
  • Davies Ward Phillip Vineberg LLP Prize in Corporations and Taxation (2010)
  • R.W. Leonard Prize in Alternative Dispute Resolution (2009)
  • David Sabbath Prize in Contract Law (2008)
  • Aird & Berlis LLP Award for Academic Achievement (2008)
  • Dean’s Silver Scholar Award (2008)


  • Sufficient Certainty? The Supreme Court of Canada Rules on Whether an Environmental Order Against an Insolvent Company Can be Stayed: Newfoundland and Labrador v. AbitibiBowater Inc., by Daniel Kirby, Edward Sellers, Jennifer Fairfax and Patrick Welsh, in Key Developments in Environmental Law 2013, Chapter 1 (Toronto: Carswell, 2013). 

Pro Bono/Community Work

  • Law Help Ontario, Duty Counsel Volunteer