See biographies by M. J. Bruccoli (1984) and T. Nolan (1998).
His wife, Margaret Millar, 1915-94, b. Kitchener, Ont., Canada, was a mystery writer. Her works include The Invisible Worm (1941), The Murder of Miranda (1979), and Banshee (1983).
Macdonald was born in Toronto, Ontario, to a dry goods merchant who had immigrated from Scotland. He went on to study law at the University of Toronto and the Osgoode Hall Law School. Upon completion, he practised law in Brantford, Ontario, and served with the Canadian Expeditionary Force in the First World War.
In 1921, Macdonald married Muriel Whittaker.
Macdonald sought Liberal Party nomination to run for election to the Canadian House of Commons for the 1926 election, but lost the nomination by a single vote. He won the nomination for the Brantford riding in the next election, but lost the election. Macdonald was elected in the 1935 election. He served as Member of Parliament (MP) until 1953.
During World War II, Macdonald was a staunch supporter of conscription. His position is made clear in this wartime quote taken from a Canadian newspaper, "There is a victory to be won and that can be accomplished only by every Canadian taking part." After the war, he served as Deputy Speaker (1945-1949) and then as Speaker of the House of Commons (1949-1953).
In 1953, Governor General Vincent Massey, on the advice of Prime Minister Louis St. Laurent, appointed Macdonald to the Canadian Senate, where he became Leader of the Government in the Canadian Senate and a minister without portfolio in the Canadian Cabinet. From 1954 until the Liberal government's defeat in the 1957 election, Macdonald served as Solicitor General of Canada.
With the defeat of the Liberals, he became Leader of the Opposition in the Canadian Senate, and served again as Government Leader when the Liberals returned to power in 1963. He retired from the Cabinet in 1964. From 1964 to 1972, he was the second Chancellor of Waterloo Lutheran University. Governor General Roland Michener, on the advice of Lester Pearson, appointed Macdonald to serve as Lieutenant Governor from 1968 to 1974. In this role, he was involved with many service groups, such as the Canadian Order of Foresters and the Kiwanis Club.
He died in Toronto in 1976.