Philosophy of Law Spring 2024

Dworkin on Hart


Hart maintains judges decide cases in one of two ways:

  1. They apply legal rules to the facts in the case before them.
  2. They exercise discretion and legislate, revising the rules to give an answer to the case before them.

Dworkin seeks to show that there is a third thing judges do to decide cases: they use what he calls principles.

Dworkin also maintains that Hart’s theory, that the law is the union of primary and secondary rules, cannot accommodate principles. He says this because he believes that principles are not rules themselves and they cannot be identified using a rule of recognition.

If Dworkin can prove these points, he will have shown that Hart’s theory is incomplete.

What are Principles?

Here are some examples of principles.

  1. No one should profit from their own wrongdoing.
  2. A court’s decisions should be consistent with those made by courts in the past.
  3. A law that improves the general welfare is better than one that does not.

Principles thus range over the topics of (i) justice, (ii) the role of judicial precedents, and (iii) good policy.

In addition to examples, Dworkin gives us two abstract differences between principles and rules (Dworkin 1967, 25–27).

  1. Rules are all or nothing while principles are not.
  2. Principles have weight or importance while rules do not.

At the end of the day, I think this is going to be the most important point about principles. Dworkin thinks that the substance or “appropriateness” of principles is what matters and their origins are largely irrelevant.

For Hart, it is the other way around: origins matter more than substance. For Hart, a law is a rule that comes from a source that can make laws, no matter how stupid the rule is. For Dworkin, a principle has to make sense, no matter what its source is or even if it has no identifiable source at all.

Are Principles Part of the Law or Not?

Dworkin tries to show that Hart has to choose between saying one of two things:

  1. principles are not part of the law
  2. principles are part of the law

He maintains that this is a dilemma because neither alternative is palatable for Hart and there is no third option.

We will be quick with the first option, that principles are not part of the law, because I know that Hart thought the second option was better. He had drafted a response to Dworkin that was published in the postscript of the second edition of The Concept of Law (Hart [1961] 1994). While Hart’s remarks were incomplete, his comments all concerned the second option and ignored the first. So that is where we will concentrate our attention.

If Hart says that principles are part of the law, then he would have to show that there is a rule of recognition that we can use to identify the principles that are part of the law and distinguish them from the principles that are not part of the law. Dworkin denies that this can be done.

There could be a rule of recognition about statutes: we recognize them as law if they are passed by the legislature and signed by the executive. We could also have a rule for judicial precedents: we recognize past judicial rulings as part of the law that judges use to decide cases. But what feature of principles would we single out in a rule that we would then use to say “these principles are part of the law and those are not”?

You could say “our rule is that whatever principles are appropriate to a case are part of the law governing that case.” Is that a useful rule?

If you find it difficult to identify principles using a rule of recognition and you are persuaded that principles play an important role in the law, then you come to the conclusion that Hart’s theory is incomplete.

What Should Hart Say?

What would Hart’s best answer to this problem be? How could a rule of recognition identify the principles that are part of the law? That is the question that will occupy us for most of our time.

In discussing this, I think it would help to pay special attention to these two paragraphs from Dworkin’s article.

First, Dworkin concedes that principles have to have some institutional grounding in statutes or past court decisions.

if we were challenged to back up our claim that some principle is a principle of law, we would mention any prior cases in which that principle was cited, or figured in the argument. We would also mention any statute that seemed to exemplify that principle (even better if the principle was cited in the preamble of the statute, or in the committee reports or other legislative documents that accompanied it). Unless we could find some such institutional support, we would probably fail to make out our case, and the more support we found, the more weight we could claim for the principle. (Dworkin 1967, 41)

However, it is pretty clear that Dworkin thinks that identifying principles involves a lot more than looking backwards to find their institutional origin in a statute or judicial decision. This paragraph comes immediately after the previous one.

Yet we could not devise any formula for testing how much and what kind of institutional support is necessary to make a principle a legal principle, still less to fix its weight at a particular order of magnitude. We argue for a particular principle by grappling with a whole set of shifting, developing and interacting standards (themselves principles rather than rules) about institutional responsibility, statutory interpretation, the persuasive force of various sorts of precedent, the relation of all these to contemporary moral practices, and hosts of other such standards. We could not bolt all of these together into a single “rule,” even a complex one, and if we could the result would bear little relation to Hart’s picture of a rule of recognition (Dworkin 1967, 41)

Two Points About Judicial Legislation

There are two things that nag at me about this debate between Dworkin and Hart.

First, it seems to me that there is a mismatch between cases like the one about the vehicles in the park and the suggestion that principles play an important role in judicial decisions.

Is there a principle that tells us what the right answer to the vehicles case is? Maybe if we take “principle” to mean “policy consideration” there is. But I wonder if there are always clear social advantages from deciding a case one way or the other. If not, bringing principles into the law will not be enough to show that there is no need for judges to legislate in at least some cases.

My second point is about retrospective or ex post facto legislation. What we said last time is that judicial legislation is bad because it means someone gets fined or punished for doing something that was not clearly against the law when it was done.

Would adding principles to the law help? The idea is supposed to be that the principles are already part of the law, so when judges make their decisions they are appealing to what is in the law rather than changing the law. But I am not sure that this works. Since it is hard to tell how principles are weighed against one another, even according to Dworkin, I do not see how an average citizen would know which principles apply to which cases. But if you cannot figure out what the law is, how could it be fair to punish you for violating it? Isn’t that the real problem with ex post facto laws?

I am left with the disconcerting feeling that this is a problem that simply cannot be solved. We are always going to be liable for prosecution for violating laws that we could not have known about in advance.

Key concepts

  1. Principles vs. rules
  2. Why it seems difficult to formulate a rule of recognition that could include principles
  3. The problem of ex post facto (or retrospective) legislation for both views


Dworkin, Ronald. 1967. “The Model of Rules.” University of Chicago Law Review 35 (1): 14–46.
Hart, H. L. A. (1961) 1994. The Concept of Law. 2nd ed. Oxford: Clarendon Press.