Some have called on the President and the Senate Republicans to compromise on the replacement for Justice Antonin Scalia: The President should nominate a “moderate” candidate whom the Senate would then confirm. But any such compromise is likely a bad deal for Republicans. In modern times justices have tended to drift left, unless they were anchored in the conservative legal movement or were already on the left. Ideological ratings of justice year by year show overwhelming evidence of leftward movement. Thus, a moderate today would very likely become at least moderately liberal over time.
There are two reasons for this leftward drift. First, the current of the bar runs left. Thus, justices are surrounded by a dominant legal culture that pulls in one direction. This is not the first time that such a strong current has frustrated one side of the political spectrum. Despite their 24-year control of the Presidency, Jeffersonian-Republicans were unable to change the course of the Federalist Supreme Court. After nineteen straight years of Democratic-Republican Presidents, the Court even upheld unanimously the constitutionality of the Bank of the United States—the bête noire of Thomas Jefferson.
Second, the accolades of our elites go to justices on the left. I already detailed how Ivy League colleges have given no honorary degrees to any of the current conservative justices, including Justice Scalia, who was in his lifetime the most historically important Justice, although liberal ones were frequently garlanded. More generally, the press and the professoriate lionize justices for growing on the Court. Justices are human, and continual flattery eats away at the apparently most granite of convictions.
Curtis Bradley and Neil Siegel have suggested that there is a convention suggesting that at least if the President nominates “a relative moderate” the Senate Republicans should not object. This convention would be built on a few previous instances of confirmations in election years, like that of Justice Kennedy in 1988. But conventions, unlike textual commands, are inferences from history. Because history never repeats itself, the precise boundaries of such a convention are not clear. The vacancy that Kennedy filled did not itself occur in an election year, and the late confirmation was entirely due to the defeat of a previous nominee, Robert Bork. And the strong tendency of moderates to drift left provided another reason for the Democrats to confirm Kennedy that does not apply to the current vacancy.
The American structural Constitution, unlike the British Constitution, should not be understood as a series of conventions but a set of rules in the Constitution’s text. And the rules here are simple and clear. The President may nominate anyone he wishes, and the Senate may confirm the nominee or decline to do so at its collective pleasure. It is up to citizens to judge who is making wise use of these constitutional powers.