David Jacyk

David is the Head of Osler’s tax litigation practice in Vancouver. A career litigator on high-profile matters, David has appeared as lead counsel at all levels of Canadian courts, including the Tax Court of Canada, the B.C. Supreme Court, 3 different appellate courts and the Supreme Court of Canada. He has extensive experience in litigating tax cases for the Crown and is well-versed on controversies affecting corporate taxpayers.

Prior to joining Osler, David practised as Crown counsel in Canada and New Zealand for more than 23 years, including serving as General Counsel of the Department of Justice of Canada (Vancouver) for approximately 10 years. More recently, David was legal counsel  for the Crown Law Office and Inland Revenue Department in New Zealand (2015-2017), where he focused on revenue and public law, and appeared before the Taxation Review Authority, the High Court, and the New Zealand Court of Appeal.

Throughout his career, David has argued a wide variety of complex cases involving tax litigation, civil litigation, customs and anti-dumping, bankruptcy and insolvency, judicial review, constitutional and other matters. He is a frequent speaker and author on a range of tax issues, and received the Canadian Tax Foundation’s Douglas J. Sherbaniuk Distinguished Writing Award in 2013 for his seminal article “The Jurisdiction of the Tax Court: A Tax Practitioner’s Guide to the Jurisdictional Galaxy of Constitutional Challenges.”

Outside of his practice, David has contributed to the legal community through volunteer work, including acting as a judge at student moot competitions. He has also participated as a mentor in the Canadian Bar Association’s Student Mentorship Program and was a Council Member at a Vancouver strata corp. from 2011-2015.

Representative Work

  • Canada (National Revenue) v. Cameco Corporation – 2019 FCA 67 – David led the litigation team at the Federal Court of Appeal, which successfully secured the precedential decision establishing that the Canada Revenue Agency could not compel the interviews of 25 officers and employees of a multinational company. The decision has been widely reported, and has been identified as a critical legal precedent for limiting the Canada Revenue Agency’s audit powers. Read more.
  • Husky Oil Operations Ltd v. The Queen – 2019 TCC 136 David led the litigation team that successfully struck out numerous portions of the Canada Revenue Agency’s pleading in a tax appeal arising from a dated audit. The decision is an important procedural decision that clarifies the requirement for the CRA to accurately set out the basis for its assessment in a tax appeal, and that imposes restrictions on the CRA’s ability to expand the scope of a tax dispute at the litigation stage. Read more.
  • Exxonmobil Canada Ltd. v. The Queen – 2019 TCC 108 – A recent tax appeal concerning the rules relating to the calculation of resource allowance and  entitlement to scientific research and experimental development (SR&ED) in the context of an offshore drilling operation. The Osler litigation team successfully established the taxpayer’s ability to claim the resource allowance in relation to the pipeline loading system of an offshore drilling platform. Read more.
  • Van Lee v HMQ, 2018 TCC 230 – The CRA treated the creation of a trust as a form of tax avoidance and attributed the income tax liability of the spousal trust to the settlor of the trust, on the basis that the trust was not validly constituted under Quebec law, or was otherwise a sham. The CRA’s aggressive assessing position represented an attempt to test the law and expand the legal grounds for ignoring trusts for tax purposes, by attempting to build on principles expressed in recent case law relating to sham and tax avoidance. David was successful in having the assessment completely vacated, establishing that the trust was validly constituted under Quebec law and that neither the trust nor the initial transfers of property to the trust constituted shams.
  • Daishowa‑Marubeni International Ltd. v. Canada, [2013] 2 SCR 336, 2013 SCC 29  – a forestry tax case concerning  reforestation and remediation  liabilities that David argued as lead counsel at the Tax Court, Federal Court of Appeal and the Supreme Court of Canada. The Supreme Court case  involved interveners from the forestry and oil and gas industries;
  • Haida Nation v. Canada (Fisheries and Oceans) 2015 FC 290 – an injunction and judicial review in respect of the opening of a fishery by the Minister of Fisheries and Oceans near a national marine reserve;   
  • Century Services v AG of Canada, 2010 SCC 60, [2010] 3 S.C.R. 379 /  Re Ted LeRoy Trucking Ltd, 2009 BCCA 205, [2009] G.S.T.C. 79 – a precedent setting insolvency case concerning the priority of GST, this was one of the first cases in the Supreme Court of Canada that involved the interpretation of key provisions of the Companies’ Creditors Arrangement Act;
  • Weyerhaeuser Company Limited v Her Majesty the Queen, 2012 TCC 106 – a tax appeal involving overlapping  federal and provincial tax legislation and the adversarial intervention of a provincial government;
  • Her Majesty The Queen Right of Canada v. Domtar Inc. & Domtar Industries Inc., 2009 FCA 218  – a civil action involving a constitutional challenge to federal legislation implementing the Canada-U.S. Softwood Lumber Agreement;
  • MIL (Investments) S.A. v Her Majesty the Queen, 2007 FCA 236, 2007 D.T.C. 5437, [2007] 4 C.T.C. 235 – the first “tax treaty shopping” test case in Canada; 
  • Leroux v. Canada Revenue Agency, 2012 BCCA 63  – a precedent setting lawsuit for regulatory negligence against the Canada Revenue Agency;
  • Stanley J. Tessmer Law Corporation v HMQ, 2013 TCC 27  – a constitutional challenge to the application of the Goods and Services tax to criminal defence legal bills;
  • Amateur Youth Soccer Assn. v. Canada (Revenue Agency), 2007 SCC 42, [2007] 3 S.C.R. 217, 2007 D.T.C. 5527, [2008] 1 C.T.C. 32, 367 N.R. 264, 287 D.L.R. (4th) 4  – a case concerning the requirements for establishing charitable status under the Income Tax Act;
  • Her Majesty The Queen v. Roitman, 2006 FCA 266, (2006) 353 N.R. 75, 2006 D.T.C. 6514; [2006] 5 C.T.C. 142 leave to appeal refused [2006] S.C.C.A. No. 353  – a proposed class action case launched in the Federal Court of Canada, the decision has been cited widely as a precedent on  the issue of the Tax Court’s jurisdiction and the threshold for striking pleadings;
  • B.C. (A.G.) v Christie, [2007] 1 SCR 873, 2007 SCC  – a constitutional challenge to the application of the B.C. Social Service Tax Act to legal services, involving several provincial governments and interest groups as interveners;
  • R & R Trading Co Ltd. v M.N.R., 2006 F.C. 901, [2006] F.C.J. No.1138 (2006) 149 A.C.W.S. (3d) 1016 -a customs trial involving the imposition of anti-dumping duties and penalties on imports from Korea;

Other recent successes for clients

  • Secured a consent to judgment to vacate an income tax assessment in full in a tax appeal involving tens of millions of dollars of tax liability, shortly after filing the Tax Court appeal and prior to any discovery process.
  • Defended a claim set for a commercial arbitration relating to the exercise of a mining option arising from mining property in Mexico, leading to a successful resolution.  
  • Successfully negotiated  a recovery for a substantial portion of the client’s legal bills on an indemnity basis after having the tax assessment vacated in Tax Court.

Latest Insights

  • Webinar Dec 2, 2021

    Practical Implications of Recent Developments in the Courts

    Presented by Osler and the Tax Executives Institute The Osler Western Canada team will address recent developments in tax cases and CRA administrat...

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    Practical Implications of Recent Developments in the Courts

Awards and Recognition

  • Best Lawyers in Canada: Recognized in Tax Law
  • The Canadian Legal Lexpert Directory: Recognized in Litigation – Corporate Tax; Canada corporate tax litigation lawyers
  • Canadian Tax Foundation: Recipient of Douglas J. Sherbaniuk Distinguished Writing Award
  • Department of Justice: Appointed as Counsel on the Supreme Court of Canada’s national counsel list; Recipient of Department of Justice award for team excellence; Recipient of Department of Justice award for individual excellence for outstanding performance; Recipient of Department of Justice award for outstanding contribution

Media Mentions

  • Osler News Dec 6, 2022

    New tax disputes publication featuring contributions by Osler lawyers now available

    The Canadian Tax Foundation has just published a new book on Canadian tax disputes.

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  • Osler News Apr 22, 2021

    143 Osler lawyers recognized in the 2021 Canadian Lexpert Directory

    Osler is proud to announce that 143 of our lawyers have been recognized in the 2021 edition of The Canadian Lexpert Directory, including 12 newly ackn...

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  • Osler News Aug 14, 2017

    Osler welcomes new tax litigation partner David Jacyk to our Vancouver office

    Osler is pleased to welcome David Jacyk as a partner and the Head of our Vancouver-based Tax Litigation practice. David brings more than 23 years of e...

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Community Involvement

  • Member of the organizing Committee for Canadian Tax Foundation’s 70th Annual Tax Conference (2018).
  • Volunteer judge for the Peter Burns Mock Trial Competitions, University of British Columbia.
  • Volunteer judge for the “Barry Sullivan” Moot Cup Competition, Canadian Bar Association.
  • Adjunct Professor for the UBC Intro to Tax course for a single (three-month) term in 2012.

Speaking and Writing

Speaking Engagements

speaker 02/12/2021
Practical Implications of Recent Developments in the Courts
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speaker 16/9/2019
2019 Canadian Tax Foundation BC Tax Conference
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speaker 26/6/2019
Practical Tips for Managing Tax Risk at the Transaction, Audit and Objection Stages
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speaker 25/11/2018
Canadian Tax Foundation 70th Annual Conference
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Published Work

  • Co-Author, "Proportionality and the Train of Inquiry in Tax Court Discovery: A Search for the End of the Line" (2018) 66:4 Canadian Tax Journal, 809-46.
  • “The Application of Issue Estoppel in Tax Litigation: When Can a Conviction of a Tax Related Offence Bar a Subsequent Tax Challenge?”  New Zealand Journal of Taxation Law and Policy, Volume 24, September 2018, Number 3, page 235 – 246.
  • “The Use of Issue Estoppel in Tax Litigation: Ending Redundant Tax Challenges”, New Zealand Journal of Taxation Law and Policy, Volume 23, June 2018, Number 2, page 197 – 210.
  • “The Jurisdiction of the Tax Court: A Tax Practitioner’s Guide to the Jurisdictional Galaxy of Constitutional Challenges” (2012) 60:1 Canadian Tax Journal 55-92.
  • “The Dividing Line between the Jurisdictions of the Tax Court of Canada and Other Superior Courts” (2008) 56:2 Can. Tax. J. 661.
  • “The Integration of Article 25 Arbitration in WTO Dispute Settlement: the Past, Present and Future” (2008) vol. 15 Aust ILJ 235.
  • Res Judicata And Issue Estoppel in Tax Litigation: The Reduction of Recycling and Reusing In Tax Cases”,  2012 Tax Dispute Resolution Conference Report  Proceedings of the Tax Dispute Resolution, Compliance, and Administration in Canada Conference.



  • University of British Columbia, LL.M.
  • University of Manitoba, B.A.
  • University of Manitoba, LL.B.


  • English
  • French

Professional Affiliations

  • Mentor, Canadian Bar Association’s Student Mentorship Program, 2010-2012
  • Council Member, Vancouver Strata Corp. LMS1491, 2011-2015