Brian Leiter (University of Chicago) has posted Theoretical Disagreements in Law: Another Look (D. Plunkett, S. Shapiro, & K. Toh (eds.), ETHICAL NORMS, LEGAL NORMS: NEW ESSAYS IN MEATETHICS AND JURISPRUDENCE (Oxford University Press, Forthcoming)) on SSRN. Here is the abstract:
In "Explaining Theoretical Disagreement" (2009), I defended an answer to Dworkin's argument that legal positivists can not adequately explain disagreements among judges about what the criteria of legal validity are. I here respond to a variety of critics, in particular, Kevin Toh. I argue that Toh misrepresents Hart's own views, and misunderstands the role of "presupposition" in both Hart and Kelsen. I argue that a correct reading of Hart is compatible with the error-theoretic interpretation of theoretical disagreement I defended in 2009.