Louise R. Summerhill

Partner* Admitted to the Ontario Bar: 1990

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*Practising as a professional corporation
  • Bio
  • Awards & Recognition
  • Professional Involvement
  • Representative Matters
  • Selected Speaking Engagements
  • Selected Publications
  • Insights
  • Education

A creative thinker and natural problem solver, Louise continuously looks for new ways to approach and resolve her clients’ tax issues. Her technical expertise and knowledge of her clients’ businesses leads to solutions others may not see. When she takes matters to court, her strong advocacy skills are evident in her straightforward yet detailed presentation of the facts.

Louise is a member of the firm's Tax Group, Co-Chair of the Tax Litigation Group, and member of the Charity and Not-for-Profit Law Group. She practises almost exclusively in the area of tax litigation. She provides support and advocacy at the audit stage, through the objection procedure and in court if necessary. Louise also has extensive experience advising clients on transfer pricing, goods and services tax, provincial tax and federal income tax and charity law issues. 

She has appeared in the Tax Court of Canada, the Federal Court of Appeal, the Ontario Superior Court and the Ontario Court of Appeal. Louise was formerly the Chair of the Student Committee for the firm and Co-Chair of the firm's Women's Initiative.

Louise has been with Aird & Berlis since summering with the firm in 1987. 

Click here to learn more about Louise. 


Awards & Recognition

  • Recognized in The Canadian Legal Lexpert Directory as a leading lawyer in the area of Litigation – Corporate Tax
  • Recognized in Chambers Canada and Chambers Global as a top practitioner in Tax Litigation
  • Recognized in The Best Lawyers in Canada in Tax Law
  • Recognized as a Global Leader in Who’s Who Legal Global: Corporate Tax -  Controversy and as a National Leader in Who's Who Legal Canada: Corporate Tax
  • Recognized by ITR World Tax (Canada) as a Notable Practitioner in Tax
  • Named in Legal Media Group's Tax Expert Guide and Women in Business Law Expert Guide
  • Recognized for strong ethical standards by Martindale-Hubbell

Professional Involvement


  • The Advocates' Society
  • Canadian Tax Foundation
  • Thomas More Lawyers' Guild of Toronto
  • Women Presidents' Organization (2004 - 2009)

Community Involvement

  • Birthright International, Board of Directors
  • Philip Aziz Centre for Hospice Care, Chair, Board of Directors

Teaching Engagements

  • Co-creator and former adjunct professor of "The Course of a Transaction," Osgoode Hall Law School

Representative Matters

Successfully represented L.F. Management and Investment in the Tax Court of Canada in Husky Energy Inc. v. The King, 2023 TCC 167, which considered beneficial ownership and the general anti-avoidance rule in the context of Canada’s tax treaties with Luxembourg and Barbados. 

Advised the Ontario Ministry of Economic Development, Job Creation and Trade on all aspects of its winning bid for Volkswagen’s first overseas gigafactory, a several-billion-dollar investment that is one of the largest in Canadian history. 

Successfully represented Mediclean in the Tax Court of Canada relating to GST/HST reassessments pursuant to the Excise Tax Act.

Successfully represented the Milgram Foundation at the Federal Court of Canada in a motion to strike a judicial review application relating to the voluntary disclosure program. 

Successfully represented a group of investors in the Tax Court and the Federal Court of Appeal in R. v. Landrus, which considered the applicability of the general anti-avoidance rule to a transaction which resulted in the claiming of a terminal loss

Successfully represented Velcro Canada Inc. in the Tax Court of Canada on the meaning of "beneficial owner" under the Canada - Netherlands Income Tax Convention

Successfully represented City Water International Ltd. before the Tax Court and Federal Court of Appeal, successfully arguing that installers and maintenance repair workers were independent contractors and not employees

Representing a confidential client regarding withholding tax assessments arising out of a securities lending arrangement

Representing a confidential client regarding the general anti-avoidance rule in the context of crystallizing capital gains exempt from tax under the Canada-Luxembourg Tax Treaty

Representing a confidential client regarding myriad foreign compliance issues and substantial penalty assessments

Represented a multi-national in respect of Canada-U.S. transfer pricing methodology and competent authority agreement

Representing a client in respect of assessment altering valuation of fixed value preferred shares

Representing a trust with respect to provincial residency based on mind, management and control

Representing numerous clients with respect to commerciality in relation to chartering of private aircraft

Representing clients under audit in respect of reasonableness of management fees

Representing a confidential client regarding interest deductibility in the context of debt which the CRA has characterized as a new obligation not qualifying for deductibility under paragraph 20(1)(c)

Successfully represented Triple M Metal LP in an appeal in the Tax Court of Canada relating to an Ontario Goods and Services Tax/Harmonized Sales Tax reassessment

Overturned multi-million dollar GST assessments against non-resident GST registrants because of issues relating to audit methodologies
Successfully advocated "due diligence" on behalf of various individuals who were alleged to have director's liability for GST and/payroll taxes
Successfully overturned various tracing assessments involving non-arm’s-length transfers of property
Successfully represented Mediclean Inc. in the Tax Court, overturning a CRA assessment for EI and CPP when the Court found workers to be independent contractors and not employees
Successfully negotiated numerous voluntary disclosures to eliminate penalties in relation to unreported foreign income
Advocating for various individuals in relation to assessments following dispositions of real property

Selected Speaking Engagements

Presenter, “Audit to Appeal – Navigating the Tax Litigation Process,” AJAG, September 27, 2019.

Presenter, “What’s New at CRA/Real Estate Transactions,” Professional Accountants PD Network, February 5, 2019.

Presenter, “What’s New at CRA?,” AJAG Presentation, November 22, 2018.

Presenter, “What's New at the CRA,” Education Consortium, October 24, 2018.

Presenter, "CRA Bag of Tricks: An Update on Audit Initiatives, Voluntary Disclosures and Recent Case Law," AJAG Seminar, October 27, 2017.

Presenter, "Topical Tax Issues and Recent Cases," AJAG Seminar, November 1, 2016.

Presenter, "CRA Real Estate Audit Project – The Scary Truth," Aird & Berlis LLP Seminar, June 1, 2016.

Presenter, "Tax Litigation - Tips & Traps," AJAG Seminar, January 20, 2016.

Presenter, "Tax-A Mixed Bag of Things You Need to Know," Education Consortium, November 11, 2015. 

Presenter, "Settlements: Tax Traps For The Unwary," Aird & Berlis LLP Seminar, January 28, 2015.

Presenter, "Tax Litigation: Navigating the Process From Audit Through Appeal," AJAG Seminar, January 15, 2015.

Presenter, "Update on Tax Litigation," Aird & Berlis LLP Tax Breakfast, October 1, 2013.

Selected Publications

"Changes Are Coming to the Voluntary Disclosures Program," Aird & Berlis LLP Tax News Flash, March 2, 2017.

"Ontario Reverses Land Transfer Tax Partnership Exemption," Aird & Berlis LLP Tax News Flash, February 22, 2016.

"Beneficial Ownership of Royalties – Tax Court Respects Corporate Form," The Bottom Line, February 2012.

"Beneficial Ownership: Another Canadian Victory for Taxpayers," Tax Profile, February 2012.

"CRA ''Targets High Net Worth' Individuals," June 7, 2011. 

"Canada’s Transfer Pricing Rules," February 2011.

"GAAR – Common Sense Prevails," The Bottom Line, June 2009.

"The Murky Waters of Director's Liability after Corporate Revival," The Bottom Line, May 2009 (co-written with articling student Diana Yeung).

"Taxpayer Prevails – Again – on Beneficial Ownership," The Bottom Line, April 2009 (co-written with Barbara Worndl).

"Another Part to the Sales Tax Exemption for Manufacturers," The Bottom Line, January 2009.

"'More Than Five Full-Time Employees' – The Sensible Approach to Defining a Term," The Bottom Line, Mid-November 2008.

"More Treaty Interpretation: What is a Fixed Place of Business?" The Bottom Line, Mid-October 2008.

"Redeemer Foundation; confirming the CRA's Broad Audit Power," The Bottom Line, October 2008 (co-written with Milo Prelevic).

"When is a Foreign Worker Remunerated in Canada?" The Bottom Line, August 2008.

"Scholarship Programs do not give Rise to Taxable Benefits," The Bottom Line, July 2008.

"Beneficial Ownership by Holding Company Respected," The Bottom Line, June 2008.


  • LLB, University of Windsor, 1988
  • BA (Hons., with Distinction), English, Glendon Campus, York University, 1984
  • BA, English, St. Michael's College, University of Toronto, 1983