Edward Greenspan, one of Canada's most famous criminal defence lawyers, has died at the age of 70.

Greenspan died of heart failure in his sleep while in Arizona for the holiday break, according to family friend Bernard Gosevitz.

Greenspan rose to prominence in 1986 after he travelled across the country to speak out against the potential return of the death penalty to Canada.

He was later hired by many high-profile defendants, including German-Canadian businessman Karlheinz Schreiber, theatre producer Garth Drabinsky, and media baron Conrad Black.

Following news of his death, a number of prominent lawyers and politicians remembered Greenspan for his work ethic.

“Eddie could have been a judge, Eddie could have been on the Supreme Court,” said Toronto lawyer Ari Goldkind, “but he wanted to continue representing the people that most people in this world don't like."

Edward Prutschi, a Toronto criminal lawyer who worked with Greenspan, remembers him as “the biggest personality in that room.”

Prutschi recalls once asking Greenspan if he ever planned to retire. "He responded to me completely deadpan, completely serious, that his hope was to die in a courtroom immediately after hearing a jury return with the words 'not guilty,"' Prutschi said.

Toronto Mayor John Tory issued a statement on Wednesday calling Greenspan “large than life.”

“He was a brilliant lawyer who understood how important it is that everyone have a defence, and he was a tireless champion for human rights," Tory said.

Peter MacKay, Canada’s Justice Minister, issued a statement calling him “a brilliant lawyer, a man of enormous intellect and principled action, a credit to the legal profession in Canada and the world.”

One of Greenspan’s most famous clients was Robert Latimer, the Saskatchewan farmer who killed his disabled daughter in 1993.

The Latimer case sparked a wider debate about euthanasia in Canada.

Greenspan travelled across the country in 1986 to speak against the death penalty in Canada. At the time, Greenspan suspended his practice so he could participate in any debate or forum on the issue.

Throughout his 44-year career, Greenspan was recognized with numerous awards and honorary degrees, including the Law Society Medal in 2013, and the Advocates' Society Medal in 2009.

He was the vice-president of the Canadian Civil Liberties Association and had also been inducted into the American College of Trial Lawyers in 1991.

Greenspan leaves behind a wife, Suzy, and two daughters, Samantha, who is studying to be a lawyer, and Julianna, who is a lawyer at his firm, Greenspan Partners LLP.

Greenspan graduated from Osgoode Hall Law School in 1968.

His funeral will be held at Beth Torah Congregation in Toronto, according to a family friend.

With files from The Canadian Press and reports from CTV Toronto’s Naomi Parness and Peter Akman