Hart on Judicial Interpretation

Hart’s primary aim is to defend what he calls the separation of law and morality. The question “is this the law?” is one thing while the question “is it a morally good law?” is another thing. Hart thinks the two questions should be kept separate. This is the theme of sections 1 and 4.

A subsidiary question concerns what he calls “the problems of the penumbra” (Hart 1958, 608). These problems arise because laws require interpretation. The realists take this to show that laws cannot be rules and Hart is keen to show that this is not so. This is the theme of section 2.

Problems of the penumbra

Suppose I am a judge and that the law in my jurisdiction establishes a fine for using a vehicle in the park. It has been established that cars are vehicles for the purposes of this law. Peter’s rickshaw business runs through the park and he has been brought before me. Should he be subject to the fine or not?

This is what Hart calls a penumbral case. Rickshaws are like cars in some ways (they are both vehicles) and unlike them in other ways (they do not have combustion engines and are not self-propelled). I cannot find anything in the statute or in past judicial decisions that addresses rickshaws or anything close to them, like horse-drawn carriages or pedi-cabs. So how should I decide Peter’s case?

Examples like this are thought to undermine the theory that laws are rules. The assumption is that if laws were rules, I would be able to apply one of the rules in order to make my decision. Hart wishes to refute that point. He notes that the existence of some cases like this should not be taken to show that all of them are similar. There are vast number of cases that never make it to court because the law is quite clear.

That still leaves the question of how judges decide these cases.

One solution to the problem that penumbral cases pose for judges is to say that considerations of how the law ought to be are part of what the law actually is. The idea is that if this were so, judges could make decisions in penumbral cases by interpreting the law rather than making the law. (That is how the two questions I identified at the beginning intersect one another, such that they appear in the same article.)

Hart prefers a different path. What judges do when they decide penumbral cases is make law. So when I make my decision, I will make it so that the law either now clearly does treat rickshaws as vehicles or that it does not (provided my decision is upheld by higher courts, of course).

Conflicts between law and morality

If law and morality are completely separate, then there can be valid laws that are wicked and should not be obeyed. Hart summarizes with approval Austin and Bentham’s opinion that if laws reach “a certain degree of iniquity then there would be a plain moral obligation to resist them and to withhold obedience” (Hart 1958, 616–17).

This is not a merely hypothetical point. The experience of laws in Nazi Germany persuaded some scholars that the separation of law and morality is untenable. The fourth section of Hart’s article contains a discussion of the views of one of them: Gustav Radbruch. Specifically, Hart discusses a case in which a court rejected a defense of having acted according to the law during the Nazi period on the grounds that the law in question was immoral.

Hart thinks this was a mistake. The Nazi law was bad law, but it was still valid law. So the only alternatives were either to accept the woman’s defense or to punish her under a retrospective law.

Hart makes it clear that he thinks there would be a significant cost to punishment under retrospective law. How can it be fair to punish people on the basis of laws made after they did the things for which they are punished? His point is only that this is what the court was doing, in fact, and that it would have been better to acknowledge this explicitly.

However, there is a significant problem for Hart here too. If judges make law when they decide penumbral cases, aren’t they punishing people on the basis of retrospective law too? If I find Peter guilty of driving a vehicle in the park, he is going to be fined for behavior that was not clearly illegal at the time he engaged in it. Rickshaws will be definitively classified as vehicles for the purpose of the law only when I make my decision, after all.

More generally, I think there are significant questions Hart leaves unanswered about how judges are supposed to approach cases where law and morality conflict. Say I am a judge who is asked to apply a grossly immoral law. I could say “this is the law, but it is grossly immoral so I am going to follow Austin and Bentham’s advice and resist applying it.” Or I could say “this is grossly immoral, but it is the law so I am going to do something grossly immoral and apply it as it stands.” Neither option sounds very good.

I think that is part of the appeal of denying the separation of law and morality. If law and morality were not separate, a judge would have a third option: “this statute is too grossly immoral to be part of the law so I am not going to apply it.”

Something like that seems to have been going on in the case I described on the first day: the court refused to enforce the provision of the will that would have allowed the man collect an inheritance from the estate of the grandfather he murdered on the grounds that no one should profit from his own wrongdoing. That was not part of the statute of wills; it was a moral principle that the court applied to the case. Our next author, Ronald Dworkin, will argue that cases like this show there is a significant flaw in Hart’s theory.

Key concepts

  1. The problems of the penumbra
  2. The Nazi law case (in section 4)


Hart, H. L. A. 1958. “Positivism and the Separation of Law and Morals.” Harvard Law Review 71 (4): 593–629.