Dennis E Mahony

Practice Areas

Dennis is the head of Torys’ Environmental, Health and Safety Practice, the Co-Chair of the firm’s interdisciplinary Climate Change and Emissions Trading Practice, and certified by the Law Society of Ontario as a Specialist in Environmental Law.

Dennis provides comprehensive environmental, health and safety advice to a broad range of public- and private-sector clients, including public and private companies, federal government agencies, Crown corporations, provincial bodies and municipalities. The scope of his counsel covers virtually every industrial sector: transportation, utilities, non-renewable and renewable energy, pulp and paper, mining, chemicals and plastics, water and waste water treatment and disposal, manufacturing, financial institutions and real estate development.

On projects, Dennis works alongside developers, lenders, technical consultants, regulators and other project stakeholders to plan, develop, permit and defend complex projects, often through sensitive environmental habitats. He regularly advises from the project planning stage through the approval and construction stages and into operation. His broad advice to clients spans regulatory compliance, major and minor environmental assessment and other approvals, strategic stakeholder management, and litigation before environmental tribunals and courts. Over the past several years, Dennis and various Torys teams have successfully advised and defended more major projects than any other environmental team in the country.

Dennis also assists buyers, sellers, lenders and investors through all environmental aspects of a transaction: from acquisition diligence and agreement negotiation, to the design and coordination of deal-specific environmental liability assessments, negotiation of agreements and in handling closing and post-closing details.

Dennis has a broad regulatory practice that involves technical and strategic advice spanning the full range of issues in the environmental, health and safety field. In particular, he advises on federal and provincial environmental assessments and other approvals, contaminated sites, quasi-criminal, civil and administrative liability assessments, transportation of dangerous goods and waste, climate change, general legal compliance, legislative initiatives and Canada-U.S. cross-border issues. His work regularly involves litigation, covering environmental assessment and approval hearings, appeals of administrative orders, quasi criminal defence work and civil litigation.

With respect to climate change and emissions trading, Dennis helps clients navigate through this evolving area, including keeping them informed on the numerous domestic and international developments in the area and working on project-specific teams for everything from assessing securities disclosure requirements to emissions trading.