Riel was charged with high treason. His trial had disastrous consequences for Riel and for Canada. When it began on July 20, Riel entered a plea of “not guilty.” The jury was entirely Anglo-Saxon and Protestant. Riel’s lawyer wanted to plead insanity, saying that Riel was not responsible for his actions. Because Riel objected so strenuously to this strategy, his own lawyers had the judge rule that Riel did not have permission to speak. Nor were Riel’s lawyers allowed to speak of the grievances which led to the rebellion. The judge declared that it was Riel, not the Government of Canada, who was on trial. Damning testimony from witnesses, who insisted Riel was mentally unstable before and during the rebellion did not help.
Towards the end of the trial, Riel was given the chance to speak. After a moment of prayer, he reviewed the troubles in the northwest which lead to the Rebellion. He began with the sufferings his people had endured and the government's inactivity. He maintained with dignity that he was not insane and that he did not want to be acquitted by reason of insanity. He did not deny that he had previously been committed to a mental hospital, but pointed out that the doctors had certified he was cured. He asked if visions, prophecies and missions signifed insanity? He closed with a few eloquent comments on the sacrifices he had made and asked for justice.
On July 21, the trial adjourned for one week to allow time for the witnesses to appear. The examination of the witnesses began on July 28 and continued through to August 1. On September 18, Riel was sentenced to hang. That kicked off a series of appeals.
First the Manitoba Court of Queens' Bench affirmed the original sentence, but the execution was postponed until October 16. A second appeal to the Judicial Committee of the Privy Council was dismissed and the execution set for November 10. The Prime Minister, uncertain about a decision, yielded to pressure from Ontario and Quebec and granted a third reprieve – this time to allow a medical commission to examine Riel. The commission was unable to pronounce him insane and the date of his execution was set for November 16.
While awaiting death, Riel was visited by his family and on November 6, he penned his will. He spent his final night and early morning hours writing one last letter to his Mother and receiving the Last Rites. At 8:00 a.m., he climbed the stairs to the scaffold where he was executed by hanging. On November 19, a service for the repose of his soul was sung at St. Mary's Church in Regina. On December 9, his body was returned to St. Vital where it lay in state at his Mother’s house for two days. A requiem mass was sung December 12 at St. Boniface Cathedral and his body is buried in the churchyard.