For many areas of traditional legal studies, a more robust empiricism must be viewed as a natural, or at least uncontroversial, contribution to the field. Law and Psychology creates opportunities to think deeper about issues such as consent, the reliability of eyewitness testimony, or the factors that influence jury decision making. Law and Economics provides tools to explore a wide range of institutional dynamics and investigate the implications of various legal regimes for market practices. But I wonder whether there is something about certain areas of legal studies that makes them resistant to certain kinds of empirical analysis.
In particular: Is there something about the nature of constitutional studies in contemporary law schools that creates barriers to incorporating empirical political analysis of our constitutional practices?
Most political scientists who study law/courts produce research that has some bearing on how our constitutional system works. For example, despite my view that Supreme Court decision making cannot be reduced to justices voting their so-called "policy preferences" (see the discussion in comments here), there is no question that the justices' positions on constitutional questions is overwhelmingly related to their conventional political affiliations; what else would we expect, given our explicitly partisan selection criteria for justices (which itself is a feature of our constitutional practices)? Moreover, as Barry Friedman has pointed out (see some of the cites collected here), Alexander Bickel was aggravating over the so-called "countermajoritarian difficulty" not long after his Yale colleague Robert Dahl had demonstrated how the U.S. Supreme Court should not be expected to act in a way that was inconsistent with the preferences of dominant governing coalitions (contra Bickel, see here). Moreover, we are all now well-aware that constitutional meaning is forged in many institutional settings, not just in U.S. Reports, and that the struggle to establish dominant interpretations is a by-product of historical contexts, party systems, and inter-institutional struggles (with the best recent discussion of this here). One simply does not understand something as basic as the establishment of judicial review if one assumes that it was created via legal/textual interpretation by Marshall in his Marbury opinion (see most recently this discussion; but also Graber, "Establishing Judicial Review," 38 Tulsa L J 609  and Whittington's discussion of the Chase impeachment).
Why aren't these lessons (and others) routinely incorporated into the way traditional law professors teach or write about constitutional practices or constitutional meaning? I'm interested in your thoughts; here are a few ideas:
First, law professors may feel as though their principal teaching responsibility is to ensure that students understand how to think/advocate within existing doctrine. But (a) identifying the ways in which politics is embedded in the development of doctrine, or in divisions among various advocates, is not inconsistent with satisfying this principal responsibility, and besides (b) I have to wonder whether many teachers routinely supplement this principal responsibility by conveying to students the (empirically unsupportable) claim that constitutional law has almost nothing to do with politics.
Second, it is possible that law professors feel a professional obligation to maintain a distinction between Law and Politics. After all, this distinction is central to the way that many legal scholars conceptualize the practice of law. Many rightly believe that legal professionalism has social value precisely because it refuses to accommodate political considerations; instead, legal professionals aspire to create a practice that is dominated by the influence of legal reasoning and considerations of justice, rather than mere political will and considerations of power and interest. I would not want to undermine this aspiration; however, it is possible to maintain one's commitment to the integrity of the practice while acknowledging a simple truth about our constitutional system -- namely, that people have always had (sometimes principled, sometimes flatly cynical and opportunitistic) disagreements about how best to "interpret" the constitutional system. In other words, acknowledging the inherently contested nature of the practice does not prevent one from insisting on adopting a principled orientation to the practice. However, it does make "constitutional politics" (properly) internal to the practice, rather than treat it as either exogenous or a corruption of the practice. And at some point, the refusal to acknowledge this aspect of our constitutional reality amounts to a self-conscious decision to transform constitutional scholarship into a form of constitutional myth-making, at the expense of any sort of reality-based understanding of the constitutional system.
Third, it may just be that many traditional scholars, whose training has focused on the history of doctrine, simply don't know enough about our broader constitutional/political history to incorporate "constitutional politics" into the classroom. It's one thing to understand Marshall's essay in Marbury; it's another to understand the origins of the Judiciary Act of 1789, the politics behind the "test case" in Hylton, the significance of Schooner Peggy, the dynamics of the Jeffersonian coalition, the relationship between Marbury and Stuart v. Laird, and the impact of the Chase impeachment on the "settlement" in favor of judicial review. But if this is true for some in the law professorate then this is precisely what can be corrected if we acknowledge the need to adopt a more empirical approach to the study of our constitutional system.