Harvard economist and fellow Catonian Jeff Miron suggests that the Kagan nomination will spark renewed discussion of the question: “Should judges follow the Constitution?” I hope not, because in practice those are seldom particularly useful discussions.

I tend to agree with Ronald Dworkin that there is just not that much interesting disagreement about whether judges should “follow the Constitution” or “apply” rather than “make” law. The interesting differences between judicial philosophies are about what that entails. The cases where it’s obvious what it means to “follow the Constitution” tend not to make it before the Supreme Court—though one can of course argue that in this domain or that, no plausible theory will sustain the Court’s interpretation.

To the extent that one thinks one’s own interpretive approach is the correct one, of course, it will make sense to think of divergent rulings yielded by other approaches as failing to “follow” (the correct interpretation of) the Constitution. And there’s a rhetorical advantage to framing legal disagreement this way. But it also gives you useless spectacles like Sonia Sotomayor professing that her judicial philosophy is “fidelity to the law.”

This is sort of like learning that her moral philosophy is “a theory of how one ought to behave.” It’s not totally content-free insofar as it seems to rule out various species of nihilism or non-cognitivism, and maybe even suggests a view that focuses on rules or dispositions rather than outcomes. But it doesn’t really say what one’s theory is so much as it lays out a very broad conception of what it means to have “a moral theory.”

So I don’t want to waste any hearing time learning whether Elena Kagan thinks judges ought to follow the Constitution. I’m sure she does, and will be only too happy to wax poetic on the topic. I want to know what interpretive methods she believes constitute that fidelity. Despite her own past assaults on the “vapid and shallow parade” of judicial confirmation hearings, I don’t expect her to be too forthcoming when it comes questions about the specific conclusions those methods might yield on various hot-button issues. But there’s plenty of useful probing to be done in the vast terrain between “will you uphold the Constitution?” and “would you uphold Casey?”