I can’t track down the link, but I’m pretty sure I made the following argument a few months ago: If Justice Stevens wants to maximize the liberalism of the Supreme Court, he should convert a double vacancy to a triple vacancy by announcing his retirement.

My reasoning was straightforward. The more vacancies there were, the more unsettling the prospect of Bush’s filling all of them simultaneously would be to swing voters. It is possible to imagine Bush’s nominating three conservatives serially. It is harder to imagine him resisting the pressure for “balance” if he is faced with the task of appointing a third of the Court. If Stevens can be sure that he can hang on until there’s a Democratic president, then he’s better off waiting. But if he can’t, he might take the opportunity presented by two vacancies.

Since then, one complicating factor has arisen: Stevens seems to some extent to be in charge of the Court, and there has been talk of a “Stevens Court.” That might be an incentive to stay.

But there’s another point I didn’t mention in that earlier post that counsels in favor of leaving: Three vacancies might well qualify as an extraordinary circumstance to some crucial senators.