George MacKinnon holds a Bachelor of Laws from the University of Minnesota Law School and was an All-American javelin thrower, finishing fifth at the 1928 NCAA Track and Field Championships. He began his career as assistant counsel for Investors Syndicate, later transitioning to public service as a member of the Minnesota House of Representatives. MacKinnon served in the United States Navy as a Commander before entering private practice and holding the position of United States Attorney for the District of Minnesota. He later became general counsel and vice president for Investors Mutual Funds, and was nominated by President Richard Nixon to a seat on the United States Court of Appeals for the District of Columbia Circuit.

George MacKinnon's political identity is marked by a staunch conservatism that verges on ideological rigidity, evident in his relentless pursuit of his positions and his fierce independence. His legislative focus on accusing members of the Truman Administration for insider trading reveals a highly principled stance on economic integrity. MacKinnon's judicial career, characterized by his refusal to be swayed from his views and his ability to foster collegiality, suggests a unique blend of unwavering conviction and collaborative spirit.