Sonia Sotomayor, one of the three remaining liberal Supreme Court justices, will turn 70 years old in June, is diabetic and had one parent who died at a young age. There are some offsetting factors at work — women live longer than men, and Sotomayor undoubtedly has access to world-class health care. So I’m not going to pull out an actuarial table or pretend to precisely estimate her lifespan. However, there is clearly a chance that Sotomayor will die or become unable to carry out her duties before Democrats again control both the presidency and the Senate.

I am not the only person to bring up this touchy subject. Josh Barro has been advocating for Sotomayor to retire. And the issue has reached the mainstream: Democratic Senators…