  Interpretivism is a thesis about the fundamental or constitutive explanation of legal rights and obligations (powers, privileges, and related notions) or, for short, about the grounds of law. In the relevant sense, some fact grounds another when the latter obtains in virtue of the former; and the relation between the two facts is explanatory in a non-causal, metaphysical sense of constitutive determination. (See Fine 2012 and other essays in Correia and Schnieder 2012). Consider the fact that, if you buy a mobile phone at a store in London and it turns out to be defective, you have a right, which is enforceable through the courts, to have it replaced or repaired by the seller, provided the defect existed when the phone was delivered and became apparent not later than two years from delivery. In virtue of what does the right obtain? What makes it the case, more abstractly, that any legal right or obligation obtains?  What makes the proposition that some right or obligation exists true, if it is true? (Dworkin 1986; Stavropoulos 2017.)  What sorts of nonlegal facts do legal rights and obligations depend upon in this fundamental way, and what is the character of the relation of dependence that holds between legal rights and obligations and the nonlegal facts in virtue of which they obtain?  What is the order in which the relevant factors appear within the fundamental explanation?