In 1964, Mac was elected to the Arizona Supreme Court, the highest court in the state. The position of justice was the last elected position for Mac, the culmination of his career as a public servant.
He had served in each branch of government: in the executive branch working in the attorney general’s office and as governor; in the legislative branch as U.S. Senator; and in the judiciary at the county level as attorney and judge.
According to Mac: “This gave me another opportunity to realize one of my boyhood dreams. This was a position I had considered one of the highest in our government, but also one that I had never really expected to attain. I thought it a real challenge, since it gave me an opportunity to advance in the legal profession. At the time, justices were elected. I have always been proud of the fact that I was elected rather than appointed, because I believe in the election of Supreme Court justices.”
Mac rose to Chief Justice in 1968, thus achieving the unique political triple crown of serving in the highest position in the legislative, executive, and judicial branches of state government – the only Arizonan to ever do so.
While serving as an associate justice, and Chief Justice in 1968, Mac wrote 315 opinions. Some of the more controversial opinions Mac wrote include Arizona v. Miranda, Phoenix v. Civic Auditorium, and Lassen v. Arizona Highways Department.