The Hart-Dworkin debate is one of those philosophical arguments that is still alive because both sides keep being right about some things.
Hart's positivists make a powerful point: the separation of law and morality is not just a technicality. It protects the legal system's integrity against the risk that judges will substitute their personal moral views for the democratically enacted will of the legislature. If "best moral interpretation" is the standard, who decides what's morally best? Doesn't Dworkin's judge inevitably bring in contested political views, views about equality, liberty, and justice, under the cover of legal interpretation? At least positivism has the virtue of honesty: when the law runs out, discretion is being exercised, and we should say so and hold judges accountable for it.
Dworkin's reply: this objection assumes that legal interpretation and moral judgment can be cleanly separated, but they cannot. Every act of legal interpretation involves judgment about purposes, weights, and consistency, and there is no algorithm that does this without importing substantive values. The positivist pretense that there is a purely formal legal analysis that precedes moral interpretation is itself a political position, disguising its value choices as neutral procedure. The question is not whether judges bring values to interpretation, but whether they do so self-consciously and accountably.
Natural law theory, older than positivism, associated with Aquinas, Grotius, and modern thinkers like John Finnis, takes a third position: law is genuinely law only if it meets a minimum moral threshold. An unjust law is not merely a bad law, it is not, in the fullest sense, a law at all (lex iniusta non est lex). This seems intuitive when applied to Nazi law or apartheid law, but it creates serious practical problems: it seems to authorize resistance to law whenever individuals judge it morally defective. Risks collapsing the rule of law into individual moral anarchism.
The debate comes alive most vividly in constitutional cases. When the U.S. Supreme Court decides cases about abortion, same-sex marriage, gun rights, or affirmative action, is it finding the law, interpreting the law, or making political decisions? Dworkin's framework says the correct question is: what interpretation of the constitutional text, precedent, and underlying principles makes the constitution the best expression of a society committed to equal concern and respect for all its citizens? That question has a right answer, even if it is hard to reach and contested.
Originalists say no: the Constitution means what it meant to its framers, and any departure from that is judicial legislation. Dworkin argues that this is itself an interpretation, a particular, contestable interpretation of what it means to be bound by a constitutional text, not a neutral escape from the interpretive task.
The practical stakes are enormous. Every time a court strikes down a democratically enacted law as unconstitutional, it is making a philosophical claim about what law is, where rights come from, and what judges are authorized to do. Philosophy of law is not an academic luxury, it is the unacknowledged foundation of every legal system's most important decisions.