Contact Us

Alumni of
 Nelligan Law.

The strength of our firm is rooted in the people who have helped build it. We recognize and appreciate the alumni whose dedication and leadership have shaped our history and growth.

John Nelligan

John Nelligan, widely regarded as one of Ottawa’s most influential lawyers, began his legal career after serving overseas in the Second World War and graduating with honours from Osgoode Hall Law School in 1949. After practising in Toronto, he moved to Ottawa in 1955 and, in 1969, co-founded the firm that would become Nelligan Law. Known as “Ottawa’s Perry Mason,” John was a consummate advocate, counsel on numerous high-profile cases, and a master of courtroom advocacy.

His contributions to the profession were immense: past President of the Canadian Civil Liberties Association, first President of The Advocates’ Society outside Toronto, and Fellow of both the American College and International Academy of Trial Lawyers. Among his many honours were the Law Society Medal, The Advocates’ Society Medal, the Carleton Medal, and a Doctorate of Laws from the University of Ottawa.

John practised law for more than 50 years, shaping the firm’s reputation for excellence and mentoring generations of lawyers. He passed away on January 7, 2019, at the age of 97, leaving behind a legacy of integrity, advocacy, and dedication to justice that continues to inspire.

Denis Power

Denis Power Q.C. was born in Halifax, Nova Scotia, the fourth of ten children. The Power family moved to Ottawa in September of 1950, at which point Denis attended Corpus Christie School for one year. Following that, he attended St. Patrick’s High School at St. Patrick’s College, from which he graduated in 1960 with a Bachelor of Commerce. He then attended law school at the University of Ottawa and graduated in 1963 with an LL.B.

After completion of his articles and the Bar Admission Course, Denis Power Q.C. was called, with honours, to the Ontario Bar in the spring of 1965. He then began practising law with John P. Nelligan Q.C, who was at that time a sole practitioner. The partnership of Nelligan Power was created in 1969. Denis received his Queen’s Counsel designation in 1980.

Over the course of his legal career, Denis has been involved in many areas of law. His specialities, however, are litigation, labour law, and education law.
As a result of Denis’ involvement with education issues, he also possesses a speciality in the area of education law including denominational education rights.
Denis served for several years as a Trustee and Executive member (including the office of the President) of the local Bar Association – the Carleton County Law Association. In addition, he also served for several years as a director and officer of the Ontario Advocates’ Society. Denis is a Fellow of the American College of Trial Lawyers. The American College of Trial Lawyers is the premiere litigation lawyers’ association in North America.
Denis has written and lectured extensively on various legal matters and, in particular, on behalf of the Carleton County Law Association, the Law Society of Upper Canada, and the Canadian Bar Association.
In November 2000, Denis Power Q.C. was appointed a judge of the Ontario Superior Court of Justice in Ontario.
Catherine Helen MacLean

Catherine MacLean began her extraordinary legal career at Nelligan Law in 1977, joining as a junior lawyer under the mentorship of the firm’s founder, John Nelligan. Over the years, she became one of Canada’s foremost labour lawyers, specializing in federal public service law and shaping the landscape of labour rights through precedent-setting cases before the Supreme Court of Canada, the Federal Court, and numerous tribunals. Her work championed pay equity, collective bargaining rights, and protections against discrimination, including one of the first cases to recognize same-sex bereavement leave.

Beyond litigation, Catherine served on the Advisory Committee on Labour/Management Relations in the Federal Public Service, taught advocacy to law students, and represented union interests on NAV Canada’s Board. She was widely respected for her brilliance, mentorship, and unwavering commitment to social justice.

On January 27, 2001, Catherine’s life was tragically cut short when she was struck and killed by an intoxicated driver while walking with a friend. Though her passing was sudden and senseless, her legacy endures and is a testament to her passion for justice, her generosity of spirit, and her profound impact on the legal profession.

Allan (Al) Rodney O’Brien

Al O’Brien began his legal career at Nelligan Law as an articling student and returned after his call to the Bar in 1975 to work alongside John Nelligan. For more than four decades, Al was a cornerstone of the firm. He was an exceptional advocate, trusted advisor, and generous mentor. Known for his professionalism, intellect, and empathy, Al handled some of the most complex cases with wisdom and grace, earning a reputation as one of Ottawa’s most respected counsel.

Throughout his career, Al was an active member of the County of Carleton Law Association and The Advocates’ Society, and in 2005 was named a Fellow of the American College of Trial Lawyers. Even as illness limited his practice, Al remained deeply engaged, always committed to advancing his clients’ interests and upholding the law as a force for good.

On April 4, 2021, Al passed away peacefully at age 75 after a courageous battle with Multiple Myeloma. His legacy lives on in the countless lawyers he mentored and the clients he served. Al will forever be remembered as part of the heart and soul of Nelligan Law.

Driven. Proven. Human.

Judges, Trailblazers, 
and More

We are proud to recognize the achievements of our more recent alumni who have continued to shape the legal landscape. Several have moved on to become judges, academic professionals, and community leaders.

Their accomplishments reflect the strength of our alumni community and inspire the next generation of legal professionals.

Stay Connected with Nelligan law

Don’t miss out on alumni events, firm news, and updates! Sign up for our alumni newsletter to stay informed. Keep an eye out for networking opportunities, special celebrations, and stories from fellow alumni.

Sign Up for the Alumni Newsletter