Born in Montreal, McDougall studied at McGill University before enlisting in Princess Patricia's Canadian Light Infantry during World War II. He was sent overseas, where he served as an officer during Canadian participation in the Italian campaign. He was awarded the Distinguished Service Order and was mentioned in dispatches.
After the war, McDougall returned to Montreal, where he became Registrar of McGill University, his place of employment for the rest of his life. He died in 1984.
In 1951, McDougall began writing short stories, three of which were published in the Canadian magazine Macleans, with two more appearing in the American periodicals This Week and New Liberty. One of the Macleans stories, "The Firing Squad," concerns a Canadian soldier who is sentenced to be executed for treason by his own army. The story won several awards, including First Prize in the Macleans fiction contest, and became the basis for Execution.
McDougall wrote Execution between 1952 and 1957, keeping copious notes on its development that are now preserved in the McDougall Papers at the Rare Books and Special Collections Division, McGill University Libraries. Based loosely on McDougall's own experiences in Italy during the war, and on the real-life execution of Canadian Private Harold Pringle, the novel is both a harrowing depiction of men in combat and a philosophical meditation on the ethics of war. The novel was praised by such writers as Saul Bellow, Vera Brittain, and Hugh MacLennan, all of whom wrote to McDougall to express their admiration for his work (these letters are also in the McDougall Papers at McGill).
Despite plans to write followups to Execution, McDougall never wrote another novel. In 2005, Execution was reissued in a paperback edition as part of the New Canadian Library series, published by McClelland and Stewart.