Ontario's clean energy surge is rewriting what in-house legal work looks like, and for Carlton Mathias, chief legal, ESG and governance officer at Ontario Power Generation Inc., the shift begins with attitude.
“The old model and the old stereotype of lawyers only putting up red flags and telling people to go slow … that is not the way to succeed in a modern competitive world where there's a huge demand for infrastructure build out,” Mathias says. “Time is not on our side, so we need to show ways that opportunities can be we captured. Our advice must include taking risks, but it needs to be informed.”
That philosophy sits at the centre of one of the largest infrastructure undertakings in Canadian history. Ontario Power Generation (OPG), the provincially-owned, for-profit commercial corporation that produces roughly half of Ontario's electricity through a mix of nuclear, hydroelectric and other low-carbon sources, received provincial approval in spring 2025 to proceed with construction of the first small modular reactor (SMR) at its Darlington site – a project whose total program cost is pegged at $20.9 billion, with the first unit estimated at $7.7 billion. In May 2026, Prime Minister Mark Carney and Premier Doug Ford announced a combined $3-billion federal-provincial investment, with the federal government designating the project as being in the national interest. When all four units are complete, they are expected to generate 1,200 megawatts of power, enough to serve roughly 1.2 million homes.
For Mathias, who has overseen OPG's legal function for more than 15 years in progressively senior roles, the SMR greenlight represents a step change in complexity. “We have first-of-a-kind projects,” he says. “We need highly innovative contracting arrangements with our vendor partners. We have a high volume of work from contract negotiation and development, commercial management, [and] lots of regulatory obligations.”
Governance has had to keep pace. When OPG launched its $13-billion Darlington Nuclear Refurbishment Project – a decade-long, four-unit overhaul that was completed ahead of schedule and under budget in March 2025 – the board created a dedicated standing committee in 2014 solely to oversee that program. As the refurbishment neared completion, that committee evolved into the Major Projects Committee, which now provides oversight of the SMR project, the Pickering Nuclear Refurbishment Project, and other enterprise-level project work. Independent review boards composed of nuclear industry and mega-project experts from Canada and the United States conduct regular interval site visits within each year, report findings directly to the board, and track action items at subsequent committee meetings. “This gives the board a direct window into how management is doing, how the projects are progressing, and what improvements need to be made,” Mathias says.
The scale of OPG's capital program also raises the stakes around supply chain management. The corporation's annual procurement runs at approximately $2.7 billion, and Mathias is deliberate about what he expects those dollars to accomplish. Canadian suppliers and contractors need a credible pipeline of work before they will invest in the training centres, apprenticeship programs, and equipment required to support a nuclear build at scale. The SMR program offers that runway: because units 2, 3, and 4 will closely replicate unit 1, suppliers can anticipate repeatable performance that will improve over time. “The technology, the work that we do here, it's then translatable across the world,” Mathias says. “We have got countries from all around the world knocking on OPG's door on a regular basis about what we are leading on the SMR front because they want to learn from us and replicate it at home.”
On Indigenous participation, OPG begins engagement before a technology or design is even selected, and looks to structure economic participation on a community-by-community basis. The corporation's history with equity partnerships in hydroelectric projects – going back to 2005 – informs a framework applied to new nuclear as well. In the Moose River Basin, early-stage co-planning with Indigenous communities is underway, and the Williams Treaty First Nations, whose territories include the SMR at Darlington and the proposed Wesleyville site, are in active discussion with OPG.
The shift in how investors and credit rating agencies view nuclear energy has also reshaped Mathias's ESG workload. Where nuclear once faced an inherent discount in ESG credit assessments – driven by concerns about incidents and waste – the picture has changed. “Once you need large amounts of this type of low emissions energy, nuclear has to be part of the supply mix,” he says, noting that investors are now seeking exposure to nuclear and that credit rating agencies are looking more favourably on well-governed utilities demonstrating the capacity to execute. “The nuclear industry is highly unique in that every gram of its waste is accounted for and safely managed,” Mathias says.
For lawyers looking at the energy sector from the outside, Mathias lists many areas where legal work is being done. Contracting, construction, regulatory, employment, labour relations, environmental, Indigenous rights, capital markets – nearly every practice area intersects with electricity, a sector that is heavily unionized and subject to continuous oversight by the Ontario Energy Board, the Canadian Nuclear Safety Commission, and other regulatory bodies. “The entire electricity and energy sector needs lawyers with all kinds of expertise,” he says. “It's a dynamic, challenging and rewarding sector to work in.”
What separates effective in-house counsel in this environment, Mathias argues, is the ability to translate between legal and business – and to absorb operational reality directly. “Strong legal skills are table stakes,” he says. OPG's lawyers visit plants and project sites regularly so that, as Mathias puts it, they are not conducting paper exercises. “When you're solving a legal problem, it's really something you're thinking about in three dimensions, not just black and white on a piece of paper.”
Carlton Mathias is a member of the Canadian Lawyer Leaders Network.