
Warren Mitchell graduated from law school at the University of British Columbia in 1962, and articled with Allen McKimmie. He practiced there briefly after being called, but soon joind the Department of National Revenue in Ottawa, with the responsibility to litigate tax cases for the Department in Western Canada.
Mr. Mitchell's most notable impact on the legal world is founded on his experience as a tax litigator. In 1965, he partnered with Pat Thorsteinsson to form a tax boutique firm known as Throsteinsson Mitchell. Thorsteinssons would become a leading tax firm in Canada, with offices in Toronto and Vancouver. Mitchell spent his career arguing cases before court in BC and Ontario, as well as in front of the Federal Court in Ottawa.