John O’Sullivan M.A., LL. B.

JOS photo crop

John O’Sullivan set up a boutique litigation practice in 2012 after 25 years with an established Toronto firm.  He draws on the network of lawyers and other professionals he has developed over the years, to assemble a team of the size and expertise required to handle each file. Read more >




(These lawyers are not employees, associates, or partners of John O’Sullivan)

Andrew Burgess

Andrew Burgess has worked with John O’Sullivan on a variety of  litigation involving derivative actions, estate freezes, constructive trusts and an application for leave to appeal to the Supreme Court of Canada. Andrew has a broad civil, regulatory and criminal litigation practice. His experience includes sophisticated commercial disputes and internal investigations.  Prior to starting his own firm Andrew Burgess Law, Andrew worked as an associate at Stikeman Elliott LLP and Addario Law Group LLP, and also clerked for Chief Justice McLachlin at the Supreme Court of Canada. Andrew graduated from law school at the University of British Columbia Law School at the top of his class.

Andrea Tratnik


Andrea is an associate lawyer at Beard Winter LLP. She was called to the Bar of Ontario in 2012.  She provides top-notch junior lawyer services in contentious trusts and estates matters. She combines a talent for incisive problem analysis, with powerful legal research skills.

In her practice Andrea advises clients on a wide range of matters pertaining to estate planning and administration, international and domestic trusts, guardianship, and succession planning. She also establishes and advises privately-held companies, including not-for-profit organizations and charities.

Andrea has written and co-authored articles on several topics for Canadian and international publications, including articles on taxation, trusts, and estates law.



Jessica Gagné

Jessica Gagné works with John O’Sullivan on contentious trusts and estates matters wherever family law expertise is required. She is a family and child protection lawyer based in downtown Toronto. She represents clients at all levels of court in Ontario and before the Child and Family Services Review Board. Jessica has a particular interest in appeals. Following her clerkship at the Supreme Court of Canada and prior to launching her own firm, Jessica practiced at a leading child and family law boutique firm in downtown Toronto. Jessica graduated at the top of her class at University of Victoria Faculty of Law. She is an active member of the Toronto legal community and has won numerous legal prizes and awards.





Forensic accounting, damages quantification, business valuation

Nancy Rogers C.P.A., CA, I.F.A., C.B.V., C.I.P., C.F.F.,






Peter Macaulay, C.A., I.F.A.

Screenshot 2016-09-01 15.04.21



Nancy and Peter are two outstanding litigation accountants with whom John O’Sullivan has worked over the years.  They are adept communicators of complex matters in simple form. Their focus is to deliver reports and analyses in a form that is clear and digestible, for clients , judges and lawyers.


Hilary Katamay

Hilary oversees the preparation of material to be filed in court, supervises service and filing, liaises with clients, court staff and other lawyers.