David Atkinson points out an interesting anomaly near the beginning of his book, Leaving the Bench: scholars have spent an enormous amount of energy studying entrance to the Supreme Court-how justices are chosen-but much less studying exit. It is indeed an important issue. Do justices stay too long (or perhaps leave too early)? What mechanisms are in place to induce them to leave the Court when the time has come, and passed? Are further mechanisms needed?
Friedman, Richard D. Review of Leaving the Bench: Supreme Court Justices at the End, by D. N. Atkinson. Am. J. Legal Hist. 44, no. 4 (2000): 447-9.