Deirdre is Co-Chair of Osler’s Regulatory, Indigenous and Environmental practice. Deirdre practices energy regulatory, Indigenous and environmental law and advises clients on the regulatory and environmental aspects of power, electricity, oil and gas and other energy developments, including regulatory proceedings for setting rates and tariffs.
She advises on power transmission, distribution and generation projects in Alberta and regularly appears on behalf of clients before the Alberta Utilities Commission. Deirdre also has experience with matters before the Alberta Energy Regulator, the Canada Energy Regulator and other regulatory agencies and tribunals, including Alberta Environment and Protected Areas, the Alberta Environmental Appeals Board, the British Columbia Utilities Commission and the Yukon Utilities Board.
Deirdre also has widespread experience in environmental impact assessments required under provincial and federal laws. She has advised on power transmission lines, renewable and other power generation, oil and gas wells, pipelines, oil sands developments, upgraders, gas storage, and waste disposal facilities.
Deirdre’s Indigenous law practice focuses on consultation, accommodation and participation of Indigenous groups in relation to large energy projects.
Representative Work
- Canada Growth Fund
The Canada Growth Fund in its connection with its carbon credit offtake agreement and $200 million strategic investment in Entropy Inc.
- ATCO Electric Ltd., in transmission tariff proceedings before the Alberta Utilities Commission
- Undisclosed client, in Canada Energy Regulator gas export licensing requirements and related issues
- ATCO Electric Ltd., on all facility approvals before the Alberta Utilities Commission for an 80-kilometer 240 kV transmission line
- Various clients, in Alberta Energy Regulator related matters, including with respect to gas storage projects, waste disposal and facility approvals for sweet and sour gas facilities, and hydraulic fracturing
- ATCO Gas, a performance-based ratemaking regulated utility, before the Alberta Utilities Commission in respect of capital costs adjustments to be reflected in rates for 2014 and 2015
- Undisclosed client, in Canada Energy Regulator compliance and investigation matters
- Undisclosed client, in Alberta Energy Regulator compliance and investigation matters
- Lead Counsel to Alberta PowerLine LP, a transmission facility owner, on all facility approvals before the Alberta Utilities Commission for the Fort McMurray West 500-kV Transmission Project, designated as Critical Transmission Infrastructure between Edmonton and the Fort McMurray area of Alberta, including in respective of environmental impact assessment and Indigenous consultation issues
- Yukon Electrical Company Limited, in regulatory approvals and re-licensing of a hydro project before the Yukon Water Board, including in respect of environmental impact assessment and Indigenous consultation issues
- A large oil and gas producer regarding First Nations consultation in relation to energy project developments on reserve lands and traditional lands of various First Nations in Alberta and British Columbia
- Undisclosed client, in regulatory approvals for a solar project in Alberta
- ATCO Utilities, in proceedings to establish the 2018-2020 Generic Cost of Capital for Alberta-based regulated utilities
The Canada Growth Fund in its connection with its carbon credit offtake agreement and $200 million strategic investment in Entropy Inc.
- Various clients, in Alberta Energy Regulator related matters, including with respect to gas storage projects, waste disposal and facility approvals for sweet and sour gas facilities, and hydraulic fracturing
- ATCO Gas, a performance-based ratemaking regulated utility, before the Alberta Utilities Commission in respect of capital costs adjustments to be reflected in rates for 2014 and 2015
- Undisclosed client, in Canada Energy Regulator compliance and investigation matters
- Undisclosed client, in Alberta Energy Regulator compliance and investigation matters
- Lead Counsel to Alberta PowerLine LP, a transmission facility owner, on all facility approvals before the Alberta Utilities Commission for the Fort McMurray West 500-kV Transmission Project, designated as Critical Transmission Infrastructure between Edmonton and the Fort McMurray area of Alberta, including in respective of environmental impact assessment and Indigenous consultation issues
- Yukon Electrical Company Limited, in regulatory approvals and re-licensing of a hydro project before the Yukon Water Board, including in respect of environmental impact assessment and Indigenous consultation issues
- A large oil and gas producer regarding First Nations consultation in relation to energy project developments on reserve lands and traditional lands of various First Nations in Alberta and British Columbia
- Undisclosed client, in regulatory approvals for a solar project in Alberta
- ATCO Utilities, in proceedings to establish the 2018-2020 Generic Cost of Capital for Alberta-based regulated utilities
Latest Insights
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Osler Update April 16, 2025
Paving the way: Alberta Minister of Affordability and Utilities tables Bill 52 – Energy and Utilities Statutes Amendment Act, 2025
Bill 52 has been tabled by the Alberta Minister of Affordability and Utilities.
Read more
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Blog April 3, 2025
Major developments in Indigenous law in 2025
2025 has already seen several important developments touching on Aboriginal rights, the duty to consult, UNDRIP, land-use planning and more.
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Blog March 31, 2025
Recent decisions on the duty to consult, treaty rights and legislative updates
We discuss a few recent decisions and new legislation affecting the duty to consult and treaty rights.
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Webinar March 25, 2025
Indigenous Law Insights: meaningful consultation and Indigenous loan guarantees
The latest's developments of our monthly Indigenous Law Insights webinar series. In this session, Deirdre Sheehan, partner and Co-Chair...
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Awards and Recognition
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Chambers Canada: Canada’s Leading Lawyers for Business: Recognized in Energy: Power (Regulatory)
- “Deirdre is extremely knowledgeable and provides practical advice and guidance.”
- “She looks at issues in a strategic manner and understands the commercial implications.”
- “Deirdre provides smart and insightful support that is well thought out and reasoned – I can count on her for fantastic analysis.”
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Legal 500: Recognized in Aboriginal Law, Energy and Natural Resources (Power)
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The Canadian Legal Lexpert Directory: Recognized in Aboriginal Law, Energy (Electricity), Energy (Oil & Gas), Environmental Law
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Lexpert Special Edition: Recognized in Energy
Media Mentions
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Osler News April 30, 2025
14 Osler lawyers recognized in Lexpert Special Edition: Infrastructure 2025
Osler is pleased to announce that 14 of our lawyers are featured in the Lexpert Special Edition: Infrastructure 2025.
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Media Mentions January 8, 2025
The push for electrification – Alberta Law Review
In an article for the Alberta Law Review, authors Deirdre Sheehan, partner and Co-Chair, Regulatory, Indigenous and Environmental; Vivek Warrier,...
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Osler News September 25, 2023
22 Osler lawyers recognized in Lexpert Special Edition: Energy 2023
Osler is proud to announce that 22 of our lawyers are featured in the Lexpert Special Edition: Energy 2023, recognizing leading lawyers in the oil...
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Osler News February 22, 2023
Deirdre Sheehan joins Osler’s Regulatory, Indigenous and Environmental practice in Calgary as a partner
Deirdre Sheehan has joined Osler’s Regulatory team in Calgary with extensive experience in the regulatory and environmental aspects of electricity,...
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Speaking and Writing
Speaking Engagements
Indigenous Law Insights: meaningful consultation and Indigenous loan guarantees
Read moreIndigenous Law Insights: Métis Nation within Alberta self-government agreement and negotiating with the Canadian government
Read moreJasper Research Seminar 2024
Speaker, “The Push for Electrification and a Net Zero Grid – Developments, Reactions and Implications”, June 13, 2024 (with Vivek Warrier and Laura Scott)
Published Work
- “The Push for Electrification and a Net-Zero Grid: Developments, Reactions, and Implications”, Alberta Law Review, Vol 62, No 2: Energy Law Addition, January 8, 2025
- First Nations increasingly moving from accommodation to equity and shared ownership: On energy projects, courts are putting new spin on the duty to consult, Lexpert, October 5, 2022
- Ermineskin decision involving Coalspur mine adds novel twist to the duty to consult, by David Bursey and Deirdre Sheehan, Canadian Mining Journal, October 8, 2021
- Limiting the right to procedural fairness: New Alberta regime expands administrative powers and penalties (Deirdre Sheehan, Brynne Harding, Patrick Schembri), May 26, 2021
- “Environmental and Regulatory Issues during the COVID-19 Pandemic“, presentation to the CBA Environmental Law Section South, April 20, 2020
Credentials
Education
- University of Victoria, LLB, 2001
- University of Alberta, BEd, 1996
Languages
- English
Professional Affiliations
- Law Society of Alberta
- Canadian Bar Association (Administrative Law, Alberta South, Executive Member)
