The Monkey Cage writes Knowing When to Take off the Robe: Who Should Decide?
"The broader point is that the whims of one unaccountable person, whatever their age, abilities or ideology should NOT matter so much in a democracy. Term limits for the Supreme Court would address the much discussed possibility of strategic retirement, in which a Justice chooses to leave the bench at a time when there is a President likely to appoint a replacement with similar views, reduce the variation in the number of appointments each President gets, reduce the likelihood of Justices serving into their dotage and keep the Court from becoming too out of touch with society. This is an issue that Monkey Cagers have addressed in the past, without reaching consensus, but it is again timely.
Such a reform could be structured in various ways, but if, for example, Justices knew that if they retired during the term of a President with similar views he or she would only be able to appoint someone to serve out the remainder of their term, their incentive to retire strategically would disappear. At the same time the term limit would keep Justices from staying on the Court beyond the time when they could serve effectively, as Justice Thurgood Marshall and others did, in hopes of waiting out a Chief Executive they disliked."
"A mandatory retirement age would be an improvement on the status quo, but would still encourage Presidents to nominate young Justices, to maximize their long-term impact ,e.g. Clarence Thomas. An 18 year term would greatly reduce that incentive. Our system is backward. We limit the terms of the elected President, but not those of the unelected Judges."