Felix Frankfurter (1882-1965) joined the Supreme Court directly from the Harvard Law School faculty, serving from 1939 to 1962.
The correlation between prior judicial experience and fitness for the functions of the Supreme Court is zero.
Adam Liptak, Sidebar: Roberts Sets Off Debate on Judicial Experience, Feb. 16, 2009, The New York Times (quoting Frankfurter's "blunt assessment" in 1957 of trend towards appointing lower federal court judges to Supreme Court).

