William J. Brennan, Jr. (1906-1997) served on the U.S. Supreme Court for 34 years, starting in 1956. During this time he consistently championed libertarian rulings and an expanded interpretation of the Bill of Rights and the Civil War amendments.

Born in New Jersey in 1906, a magna cum laude graduate of the University of Pennsylvania, William J. Brennan, Jr. was a scholarship student at Harvard's School of Law. His legal career had taken him to the New Jersey Supreme Court when he was nominated to the U.S. Supreme Court by President Dwight Eisenhower in 1956. After an initial recess appointment, the Democrat, Roman Catholic jurist was Senate-confirmed with the single dissenting vote of Joseph R. McCarthy of Wisconsin.

Professor Felix Frankfurter had always admonished his students not to be unduly swayed by professorial advocacy, that their guiding motto should be "think for yourself." Years thereafter, when he served with one...