  On the first way of understanding the claim, institutional practice constitutes by itself part of the law; moral facts constitute by themselves another part; and the final content of the law is some function of the two parts. On the second, institutional practice is one factor in the explanation but does not constitute any part of the law. Rather, morality and institutional practice both figure in the constitutive explanation of the law in the sense that the practice determines the content of the law as certain moral facts dictate and in virtue of those facts.