Nathalie Mercier-Filteau – WSP Canada

As deputy general counsel, assistant corporate secretary and now head of legal for the transportation & infrastructure sector for WSP Canada, Nathalie Mercier-Filteau brings more than just legal acumen to one of the world’s top professional services firms. With nearly 13 years at the company, she has become a driving force behind a new era of collaborative, forward-looking legal leadership. Her journey—from solo in-house counsel to one of the key leaders of a nearly 40-person legal department—mirrors the firm’s transformation and growth, and her influence continues to resonate far beyond WSP’s legal team.

Nathalie Mercier-Filteau | WSP | Deputy General Counsel & Head of Legal for Transportation & Infrastructure

WSP, a global leader in engineering, environmental consulting, and design, employs over 73,000 professionals—known as “Visioneers”—across 50 countries. The Canadian arm alone boasts 13,000 professionals delivering innovative projects across sectors, including Transportation & Infrastructure, Property & Buildings, Earth & Environment, Water, Power & Energy, and Mining & Metals. As part of this vast and complex organization, Mercier-Filteau’s work spans corporate affairs and governance, mergers and acquisitions, integration strategy, and strategic legal advice to WSP Canada’s operations and regional leadership, and now legal commercial leadership for the transportation & infrastructure sector.

Building teams, bridging functions

At the heart of Mercier-Filteau’s leadership style is her unique ability to build and sustain high-performing teams. She leads—with kindness and dedication—her subgroups responsible for corporate affairs and governance, commercial matters and integration strategy—most recently assuming oversight and leadership of a legal team dedicated to one of WSP Canada’s four strategic sectors, transportation and infrastructure.”

Over the last 13 years, I’ve built and maintained many teams,” she explains. “They have proven to be very stable, collaborative and resilient groups, with low turnover and high engagement scores on our internal assessments. That kind of consistency comes from empowering people and trusting them to deliver.”

Her legal team supports the firm’s professionals from the earliest stages of project development—responding to RFPs, reviewing and negotiating contracts, and preventing project disputes, claims and litigations. And she’s increasingly stepping into business-side roles as well, acting as a legal voice at WSP Canada’s regional leadership tables and engaging with international initiatives tied to infrastructure and transport.

“Much of what I do now is focused on understanding issues and challenges, facilitating the processes, and finding solutions to ensure legal strategies are aligned with operational realities. At the heart of things, I view myself as a facilitator; I manage great professionals and nurture relationships, always keeping a client-centric approach.”

A new model for legal leadership

Recognizing the evolving demands on in-house counsel, Mercier-Filteau helped shape WSP’s senior legal leadership team in late 2022, participating in a year-long co-leadership development journey with external experts. The goal was not to sharpen individual performance—everyone was already excelling—but to elevate the group’s ability to lead collectively, across disciplines and sectors.

“It was an amazing experience,” she says. “It shifted how we think about legal leadership—not as silos, but as a shared, strategic function. We wanted to build a model that empowered everyone and that drew on everyone’s individual, unique strengths to deliver projects and initiatives collectively.”

Inspired by that program, she launched a group coaching initiative within the Canadian legal department, inviting 20 colleagues to participate in small-group sessions focused on soft skills, professional development, communication, strengths-based development and team dynamics.

“Law school doesn’t teach you how to manage people,” she says. “Even in law firms, that part of leadership isn’t emphasized. But if we want to scale and grow while maximizing efficiencies for the business and truly support professional development of our team members, we need to invest in those capabilities.”

She’s also known for recognizing potential in others and encouraging internal advancement. One recent example involved a member of her corporate team whom she encouraged to take on a management role, offering mentorship and reassurance along the way.

Pushing back barriers in construction law

In 2025, Mercier-Filteau became one of the first (if not the first) in-house counsel solely from the architecture and engineering side of the construction industry to be inducted as a Fellow of the Canadian College of Construction Lawyers (CCCL). As the CCCL is a historically selective legal body, with currently only 188 members across Canada, including 30 from Quebec and 31 women, Mercier-Filteau’s induction was a moment of great personal achievement and a larger milestone for the professionals in the construction industry.

“It was such a humble and moving honor to be invited to join such a prestigious group of highly accomplished lawyers in our vast industry,” she says.

Her presence within the CCCL brings new depth to the organization’s collective expertise, particularly in areas where professional consultants are involved, such as project delivery, professional liability, insurance, advisory services and cross-disciplinary integration. It also affirms the growing influence of in-house voices in technical, professional environments like WSPs, and advances gender and regional diversity in a historically selective legal body that is evolving with the industry.

“Our role as in-house counsel in a professional firm is evolving,” she says. “With the increasing complexity of infrastructure projects’ delivery, having legal teams embedded in technical environments is no longer a luxury—it’s essential.”

Mentorship, diversity & the future

Mentorship is a key theme in Mercier-Filteau’s career. WSP’s legal team has bolstered its mentorship process in recent years, and Mercier-Filteau both mentors junior lawyers and receives mentorship herself—from a senior global leader outside her immediate reporting structure.

“There’s tremendous value in being mentored by someone inside your company who isn’t your manager,” she says. “It gives you perspective, objectivity, and space to grow and challenge yourself. It broadens your horizons and helps you become a well-rounded strategic partner for the business and others in the industry”.

She is also passionate about inclusion. While WSP’s legal department is roughly gender-balanced, Mercier-Filteau has spent most of her career as one of the few women in construction-related legal settings. That landscape is shifting, however.

“We’re seeing more women become construction law Fellows, and more female leaders in our business,” she notes. “Our Canadian President is a woman, and that positively contributes to how we build teams, work collaboratively and support one another.”

WSP’s leadership includes women at the highest levels, including executive positions. It’s a culture that values authenticity, growth, and shared purpose—principles Mercier-Filteau embraces in her approach to hiring, team building, and succession planning.

“When I bring someone new into the team, they’re my most precious asset,” she says. “They arrive with fresh eyes and a new perspective. I want them to ask questions, challenge assumptions, and help us improve our ways of working and get better.”

Looking ahead to WSP Canada’s next strategic plan, launched in February 2025, Mercier-Filteau is eager to help shape not only legal operations but also broader business outcomes.

“I’ve learned that legal strategy is just one part of leadership,” she reflects. “The real work is about aligning people, making sure they’re in the right roles, building trust, and delivering as a team. That’s how you lead in a place like WSP.”