Some good knowledge about judicial history displayed in the discussion. Let me comment on a few of the issues-much of the discussion is among you that may continue.
The two law professors I refer too- Carrington and Cramton- believe that a change to term limits for Supreme Court Justices would not require a constitutional amendment. They and others believe that it would be constitutional for Justices after their terms are finished to become sort of roving judges at lower federal courts. I accept that conclusion.
It should be rather obvious that there would be less incentive to appoint young judges since they would have limited tenures, largely regardless of their ages. Under the present lifetime system, their expected length of service would be positively related to how young they are. Term limits are better than fixed retirement ages for several reasons. One being that even with a fixed retirement age, the incentive to appoint young Justices is still strong.
There is a concern that political jockeying by candidates would become more important than at present, but I believe the opposite would be true. There is now enormous and various kinds of jockeying among judges and other potential appointees, such as avoiding a paper trial, writing less controversial opinions, and in other ways. The prize now is a term at the highest level of 30 or more years for the typical appointee. Term limits reduces the size of the prize. The scrutiny by the Senate of every single opinion also should decline because the duration of each appointment would be much shorter.
When the Constitution was adopted, life expectancy at age 25 was more than 25 years lower than it is now. So life-time tenure for Justices appointed at age 40 meant an expected tenure of about 20 years, while now it means about 45 years. If the Founders had anticipated such a huge change, I believe they would have imposed either a retirement age or a maximum term.
At least one of you asks quite properly about the evidence indicating that we need a change toward term limits? I did present what evidence is available on the increase in average length of terms actually served by Justices, the growing infrequency of appointments, and the increasing controversy of appointments. All this means that Justices have become much more important, and less subject to natural forces of death or retirement.
It would be great to also have a detailed evaluation of the nature of their opinions, any changes in the degree of partisanship, the controversy generated by appointments and opinions, etc. I do not know of anyone who has done that kind of study. But the huge growth in legislation and litigation surely indicate that the importance of Supreme Court decisions has grown enormously, while the age and tenure of those making the decisions has also greatly increased. This evidence to me is highly suggestive (but it is not, I agree, ironclad proof) that a change is desirable