Thinking more carefully about what I wrote last night it is worth emphasizing that neither David Souter nor any of the other current Supreme Court justices is really a liberal in the sense of a Thurgood Marshall or a William Douglas. Neither Souter nor Ginsburg nor Breyer nor Stevens shows any real indication in exploring the social and economic justice issues implicated in the constitution’s guarantees of equality.
Consequently, one way in which the court could conceivably change as a result of Souter retiring would be his replacement by someone further left. That wouldn’t change any outcomes in the short-run. But it could be part of a longer-term project of rebuilding that branch of judicial thinking. That said, Marshall-style robust judicial liberalism is something that many progressives no longer believe in and I don’t see any indication in Obama’s record of statements or personal associations that this is something he’d be interested in doing if he had the chance.
Beyond that, it’s worth emphasizing what a macabre spectacle the life tenure on the SCOTUS is. When you hear about a candidate for the gig, you need to first go look up his or her age. Then when you hear that Elena Kagan is younger than Sonia Sotomayor you need to consider that Hispanic life expectancy is generally longer than for non-Hispanic whites. Quick — to the actuarial tables! This kind of decision-making process is unseemly and leads to unsound decision-making. It would make much more sense for Justices to serve a single fixed term of pretty long duration (12–18 years, say) followed by a decent pension.