Courtney was born January 6, 1916, in Duluth, Minnesota. He received his bachelor's degree from the University of Minnesota and his law degree from Loyola University Law School in Chicago. He was admitted to practice law in Illinois and Minnesota in 1940, shortly after joining his father's law firm in Duluth. He received his commission as a second lieutenant in the Marine Corps Reserve in February 1940 and in March of that year was placed in command of the Duluth unit of the Marine Corps Reserve, which was mobilized and sent to San Diego for training. He then served in Iceland for ten months.