Ritchie was called to the Nova Scotia Bar in 1934, but his law practice was interrupted by World War II.
He was a lecturer on insurance law at Dalhousie University, and acted as counsel to the royal commission on the terms of Newfoundland's union with Canada in 1949.
[1] In 1959, without any previous judicial experience, Ritchie was appointed by the Diefenbaker government to replace Ivan Rand on the Supreme Court of Canada.
[4] In Drybones, Ritchie wrote the majority decision for the Court, holding that a provision of the Indian Act was inoperative because it conflicted with the Canadian Bill of Rights.
[5] However, in Lavell, Ritchie wrote the majority decision holding that a federal statute such as the Indian Act could not be held inoperative because of the Bill of Rights.