About Carol Anne O'Brien, Barrister & Solicitor

Carol Anne O'Brien, Barrister & Solicitor is a solo Toronto practice founded in 2010, after Carol Anne O'Brien spent 12 years, six of them as a partner, at the business law firm Cassels Brock & Blackwell LLP. Called to the Ontario bar in 1998, O'Brien built the practice around Canadian regulatory law: helping businesses comply with the Competition Act, federal and provincial privacy legislation, and Canada's Anti-Spam Legislation, and navigate specialized regimes covering broadcasting and telecommunications, cultural industries, and food, drug, cosmetic, and medical device products. The practice works independently, and brings in other lawyers and professional service providers when a matter calls for it.

Before law, O'Brien worked in libraries and information services: as a librarian at Memorial University of Newfoundland in St. John's, a business information specialist at Polysar in Sarnia, and a library manager at Health Canada in Ottawa. That background carried into volunteer work. O'Brien served on the Board of Directors of the Southern Ontario Library Service from 2009 to 2016, an organization that supplies resources and services to Ontario's public libraries, and was Vice-Chair of the board from 2012 to 2016. O'Brien holds a B.A. Hons. from Queen's University, a Master of Library Science from the University of Toronto, and an LL.B. from the University of Ottawa.

Milestones & recognition

  • Called to the Ontario bar in 1998.
  • Established the practice in 2010 after 12 years, six as a partner, at Cassels Brock & Blackwell LLP.
  • Holds a B.A. Hons. from Queen's University (1982), a Master of Library Science from the University of Toronto (1984), and an LL.B. from the University of Ottawa (1996).
  • Member of the American Bar Association's Antitrust and Communications Law Sections, the Canadian Bar Association's Competition Law Section, and the Ontario Bar Association's Entertainment, Media and Communications Law Section.
  • Completed the Canadian Board Diversity Council's Intermediate Get On Board program for members of Boards of Directors.

In the community

  • Served on the Board of Directors of the Southern Ontario Library Service from 2009 to 2016, an organization that provides resources and services to Ontario public libraries, including a term as Vice-Chair from 2012 to 2016.
  • For a number of years, volunteered with a golden retriever as a weekly visitor at a neighbourhood long term care facility.
  • Maintains a resources page of articles tracking Canadian regulatory law developments, including Competition Act amendments, privacy law changes, and CRTC and CASL updates, published regularly from 2012 onward.

Good to know

A calendar with a checkmark beside a clockBy appointment

The neighbourhood

The practice is based at 151 Yonge Street, Suite 1500, on the east side of Yonge just south of Richmond Street, within a short walk of Queen subway station. It's a stretch of downtown Toronto's financial and business core, which fits a practice built around advising businesses rather than appearing in court: the office sits among the corporate headquarters and professional firms that make up much of its regulatory law client base.

Frequently asked questions

What areas of law does Carol Anne O'Brien, Barrister & Solicitor handle?
The practice focuses on Canadian regulatory law for businesses: compliance with the Competition Act, federal and provincial privacy and freedom of information legislation, and Canada's Anti-Spam Legislation, plus specialized regimes for broadcasting and telecommunications, cultural industries, and food, drug, cosmetic, and medical device products.
Can the firm help my business comply with the Competition Act?
Yes. The practice advises on mergers and acquisitions and on the Competition Act's marketing, pricing, and distribution provisions, as well as its criminal and reviewable conduct provisions.
Does the firm handle domain name disputes?
Yes. The practice uses the ICANN and CIRA arbitration procedures to help recover domain names registered by squatters.
My company runs contests or telemarketing campaigns. Can the firm advise on the rules?
Yes. The practice advises on advertising and marketing law, including trademarks, product claims, marketing practices, telemarketing, and promotional contests.
Does the firm advise broadcasters or telecommunications companies on regulatory approvals?
Yes. The practice advises broadcasters, distributors, and telecommunications companies on the regulatory regimes that apply to them, including obtaining licenses and participating in CRTC and Industry Canada proceedings.
How long has Carol Anne O'Brien been practising law?
Carol Anne O'Brien was called to the Ontario bar in 1998 and established this practice in 2010, after 12 years, six as a partner, at the business law firm Cassels Brock & Blackwell LLP.

Where to find them

151 Yonge Street, Suite 1500, Toronto, Ontario M5C 2W7 · 416-640-7270

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Listing compiled from the firm’s public website in August 2026. Verify licence status in the Law Society of Ontario directory ↗