In a podcast with the Bulwark's publisher Sarah Longwell, Lawyer George Conway, ex-husband of Donald Trump's former campaign manager (and current adviser) Kellyanne Conway, said that Congress could enforce term limits on the Supreme Court without a constitutional amendment. Here is how it would work.
Every odd-numbered year, the first after his or her inauguration and the second 2 years later, the president would nominate a new justice for the Court. If the Senate confirmed the nominee, the justice would be seated. Every case would be decided by the chief justice and the eight most recently confirmed associate justices. The other justices would remain on the Supreme Court and would continue to draw their salaries as justices with "senior status." However, if one of the nine voting justices were to be recused, something that might happen more often if the Court adopted or Congress mandated a tougher code of ethics, then one of the senior justices would step in. This could also be the case if a justice was too ill to handle a case.
The appeals courts work somewhat like this. Judges there can take senior status after they have met certain age and service requirements. Then they are still on the panel and still get their salary but do less work. Congress would essentially just introduce a modified senior status system for the Supreme Court. Conway doesn't address the problem of what would happen if the Court declared the law to be unconstitutional, but we have addressed this before. To prevent the Court from vetoing this plan, Congress would have to first strip the Court of jurisdiction in cases relating to itself.
In the event of recusal or illness, some method would be needed to determine which senior justice got to fill in. Giving the chief justice that power would be akin to giving him an extra vote. Maybe someone could write a smartphone app to pick one at random or the chief could pull a name out of a hat in public. Alternatively, there could be a round-robin system in which they took turns. Anything other than giving the chief the power to pick one would probably work. (V)