Perhaps more than any single factor, this "until death do we part"
constitutional requirement has been responsible for bruising confirmation battles. On the partisan chessboard, nailing down a Supreme Court spot is a major victory.
Other democracies employ judicial term limits. High court justices in Germany are limited to a 12-year term, and in France, Italy and Spain a 9-year term. There's American precedent for judicial term limits, for instance judges on the United States Court of Federal Claims are limited to 15-year terms.
Interestingly, for America's first twenty years Supreme Court justices averaged 13 years in service. But between 1989 and 2000 the average term for Supreme Court justices doubled, to about 26 years. Two current justices have been on the high court for more than 30 years, including the Chief Justice.
Beyond judicial term limits and a mandatory retirement age, it's also worth considering multiple appointing authorities. In France, Germany, Italy and Spain, no single person, office or institution has a monopoly on appointments to the constitutional court. Typically, this authority is shared between the upper and lower houses of the parliament, and the President or Prime Minister. In Spain, four judges are appointed by the upper-house, four by the lower house, two by the government, and two by a Judges Council.
As a step in that direction, one option is to require a confirmation vote of sixty Senators instead of a simple majority. Since no one party usually would have the required number of votes, such a higher threshold would nudge the parties towards bipartisan consensus.
It is hard to argue that a body as unrepresentative as the United States Senate should be confirming lifetime appointments, especially by simple majority vote. Out of 100 Senators, only 14 are women and five are racial minorities. But they aren't the only constituency underrepresented in the Senate.
According to Professor Matthew Shugart from the University of California-San Diego, for the past three election cycles over 200 million votes were cast in races electing our 100 Senators. Republicans won 46.8% of the votes in these elections -- not a majority -- but the Democrats won more votes, 48.4%. Yet the GOP currently holds a lopsided 55 to 44 majority. In 2004, Democratic senatorial candidates won over 51% of the votes cast, yet Republicans won 19 of 34 (56%) contested seats. So the minority party holds a majority of Senate seats.
In fact, the GOP has been over-represented in the Senate in nearly every election since 1958, primarily due to Republican success in low-population, conservative states in the West and South which are given equal representation with high-population states like California. The 52 Senators confirming Clarence Thomas in 1991 represented only 48.6% of the nation's population, showing that a Senate majority can confirm a justice for life even though they represent a minority of voters.
Defenders of the status quo undoubtedly will view any tampering as an assault on judicial independence. But the current appointment process has become deeply politicized due to lifetime appointments and simple majority votes compounded by the unrepresentative nature of the Senate.
Judicial term limits, mandatory retirement ages, higher confirmation thresholds and multiple appointing and confirming authorities would help to decrease the politicization of high court appointments, create a modest amount of turnover, and ensure that one party doesn't monopolize the process. In these times of extreme partisan polarization, that would be good for America.