Legal positivism is the leading doctrine about the nature of law. Its proponents insist that a realistic understanding of law must respect a distinction between law as it in fact is and law as we would like it to be. Ronald Dworkin's critique of positivism turns on claims about the judicial obligation in "hard cases"- cases on contested points of law. According to him, positivist judges will decide such cases in accordance with an impoverished ideal of the rule of law, one which assumes the distinction between law as it is and law as it ought to be. Such judges will thus fail to make of law the "best that it can be," an enterprise which is undertaken only when judges reject the positivist distinction and see law as a matter of moral princip...