You have to pity David Souter. By all accounts, he'd grown to hate his job. The Court was a grind. "An intellectual lobotomy," he called it. He was exhausted by the ideological jockeying. Dispirited by the institution's rightward turn. Shattered by the decision in Bush v. Gore. He loathed DC. "The world's worst city," he said. He thought often of quitting. As soon as each term closed, he'd fly home to New Hampshire and hike.
But he held fast. Because we've built our system such that a Justice who isn't unexpectedly incapacitated has to be strategic in timing their resignation. Souter did not want to be replaced by a hardline conservative. He couldn't bear to see his work undone. And so he continued to hold a job he'd long since grown to dislike.
A fixed term limit would end these perverse incentives. Give Justices 12 years of service and not a day longer. Let the political system prepare for vacancies rather than be caught by surprised. But in the absence of such a change, long-livedness remains a primary characteristic for judicial decisions. So Obama will look to choose a Justice who's relatively young. But he might also look to choose a Justice who's relatively female. According to CDC data, a 65-year-old man can, in 2005, expect to live for 17.2 more years. A 65-year-old woman gets another 20 year from the actuaries. And an Asian-American woman can expect to live even longer than that.
Think this sort of speculation is unseemly? Sure it is. But it's built into the system we've set up. If we don't want age to be such an important governing factor, then we should reform the system such that it isn't.