Judge Johnson was born just outside of Pittsburgh in Wilkinsburg, PA on August 19, 1933. He attended the University of Chicago, on an academic scholarship, leading to a Bachelor of Arts (1954) and a Bond Medal.
After graduation from college, Johnson served as a Major in the Air Force from 1954-59. His younger brother, The Honorable Livingston Morris Johnson (d. February 23, 2023), joined him in the same military branch during the final year of his first stint. In between that time, Judge Johnson returned to the University of Chicago to obtain his Law Degree (1962). He and his wife Florence moved to Pittsburgh, where he joined the law firm of Johnson (father), Johnson, and Johnson (aforementioned brother). He continued to serve in the Armed Forces from 1963-1973 (Aircraft Commander during the Vietnam War).
The Supreme Court of Pennsylvania appointed Johnson to the Pennsylvania Board of Law Examiners in 1969. In 1970, he became the Assistant Secretary and Solicitor for the City of Pittsburgh. Judge Johnson spent three years on the Pennsylvania Crime Commission before he was appointed to the Superior Court in 1980, by then Governor Dick Thornburgh. In 1985 and 1995 Judge Johnson was elected to full ten-year terms by the citizens of Pennsylvania. He retired from the Superior Court bench in 2007.
During his judicial career, Johnson served on the Court of Judicial Discipline, Disciplinary Board of Pennsylvania, Judicial Commission of the Presbyterian Church, the Pennsylvania Bar Institute, and as an adjunct professor at the Duquesne School of Law. Judge Johnson also took part in the graduate program for Judges at the University of Virginia.
The Honorable Justin M. Johnson passed away on October 29, 2021, at the age of 88.