He was the oldest of 13 children of Donald Marshall Sr., the Grand Chief of the Mi'kmaq, and his wife Caroline Googoo.
Marshall and Seale, both 17 years old, a Mi'kmaq and a boy of African descent,[5] respectively, had been walking around Wentworth Park in Sydney, Nova Scotia during the late evening with the intent to "roll a drunk" as stated in his trial.
A short scuffle occurred and Seale fell, mortally wounded by a knife blow from Ebsary.
Ebsary never admitted that he had stabbed Seale and then lied about his role to the police[citation needed] who immediately focused on Marshall, who was 'known to them' from previous incidents.
[citation needed] In response, a Royal Commission was formed to investigate what had caused the miscarriage of justice; this led to an influential case on judicial independence in Canada, Mackeigan v. Hickman.
Subsequently, Marshall reached prominence as the primary petitioner in the landmark Supreme Court of Canada case R. v. Marshall [1999] 3 SCR 456 regarding treaty rights allowing Aboriginal people to catch and sell fish under the relevant treaties.
In response to a charge from the Canadian government of catching and selling eels without a license, Marshall argued that his treaty rights superseded federal fishing regulations.