Summary of Hans Kelsen’s ‘Pure Theory of Law’


Hans Kelsen was an Austrian legal theorist, who worked in Germany until the rise of the Nazi Party, and then in the USA. He published the first edition of The Pure Theory of Law in 1934, and a second, expanded edition (which I read) in 1960.

The theory is ‘pure’ because it separates jurisprudence from other disciplines like ethics, politics and psychology. This is important because different disciplines have different methodology, and so it’s hard to analyse law when its all mixed up with other things. Kelsen’s pure theory allows for a pure ‘legal science.’

The word ‘science’ is a translation of the German Wissenschaft, which is normally translated as ‘knowledge’ or ‘study,’ and can apply to disciplines like literary theory. The English word ‘science’ is translated into German as Natur Wissenschaft i.e. ‘natural science.’ We should therefore not jump to conclusions about the relationship between legal science and natural science. Nevertheless, a comparison seems at least plausible.

Descriptive and Normative Statements

We begin the idea from Kant’s philosophy that reality can only be understood by humans through different formal categories of statements.  Here we are concerned with two categories in particular, which give two different ways of talking about reality.

The first category is ‘Descriptive Statements’ (descriptions), which deal with existence, or Kelsen’s words: “A statement that something is.” An example is ‘the door is closed.’

The second category is ‘Normative Statements’ (norms), which deal with preference, “A statement that something ought to be.” An example is ‘the door should be closed.’

Kelsen’s description of these categories highlights the words ‘is’ and ‘ought.’ I don’t like this, because it confuses the meaning of a sentence with the particular language used to express it. To decide whether a statement is descriptive or normative, you need to look at its meaning. For example:

  • A statement does not require the word ‘is’ to be a description: the sentences ‘the man runs away’ or ‘the apple will fall’ are descriptions.
  • Not all statements of the form ‘X is Y’ are in fact descriptions. For example, the statement ‘Murder is bad’ is in fact the norm ‘Murder should not be done.’

The two classes of statements are logically separate. There are no correct statements of the form ‘X is, therefore Y should be’: one cannot derive an ‘ought’ from an ‘is’. The classes also cannot contradict, i.e. the statement ‘the door should be closed’ does not contradict with ‘the door is open’ or even ‘the door does not exist.’

The two classes are related in asymmetrical ways. A descriptive statement can have a normative statement as its ‘meaning’. For example, ‘a robber says ‘Stop!’’ has the normative meaning ‘You should stop.’ We cannot conclude that the normative meaning is valid, but it is still attached to the descriptive statement. For this reason, we consider norms to be subordinate to descriptions.Picture1

It is important to keep in mind the distinction between norms and descriptions. The norm ‘Theft should be punished’ is different from ‘Theft will be punished,’ or ‘The policeman thinks theft should be punished,’ or ‘The Criminal Code says theft should be punished,’ all of which are descriptions.


We can now define legal laws as a subset of normative statements, and scientific laws as a subset of descriptive statements.

Kelsen introduces a third category that sits above normative statements. This category contains descriptive statements about norms, as opposed to about reality. The work of a legal academic contains such descriptive statements. If we care only about law, we can call these statements ‘rules of law.’ This is a horrible name – do not confuse a rule of law with ‘The Rule of Law’ meaning that the government should obey the law.

Descriptions, about reality or law, can be true or false, while norms can be valid or invalid.

Descriptions about reality contain statements about causality, i.e. statements of the form ‘If X is, then Y is.’ Rules of law contain an equivalent process called imputation, i.e.  ‘If X ought to be then Y ought to be.’ You can use causality or imputation to derive valid statements from other valid statements. For example, you could derive the norm ‘Do not kill your neighbour’ from ‘Love your neighbour.’ Imputations can also use a description as the minor premise, e.g:

Major Premise (norm): You should do what your father says.
Minor Premise (description): Your father says “Go to bed.”
Conclusion (norm): You should go to bed.

Using this method, we can derive the validity of a norm using a description and an already valid norm.

Under Kelsen’s theory, no norm is objectively valid. If we assume one valid norm then we can derive the validity of others, but any such derivation is based on this first presupposed norm.

Natural science, i.e. the study of nature, what we understand in English to be ‘science’, is the study of reality and descriptions about reality. The study of legal norms and rules of law is Kelsen’s legal science.


Law as a System of Sanction-Prescribing Norms

Kelsen’s definition of a legal system, which I shall call ‘Kelsenian law’ is a system of norms that prescribe sanctions.  A sanction is a punishment or reward that follows from a condition; an example of a sanction-prescribing norm is ‘A thief should be imprisoned.’

A ‘delict’ is an action that is prohibited by the law. An action is a delict if there is a sanction in place to discourage people from committing that action. Not all conditions for sanctions are delicts: for example, the sanction of forced quarantine may be imposed after illness. It follows that delicts are never directly prohibited, but rather are made the conditions of sanctions – there is no law that says “Do not steal,” only a law that says “Thieves should be imprisoned.”

Be aware of the distinction between ‘Thieves should be imprisoned’ and ‘Thieves will be imprisoned’ – the latter is a not a norm but a description, and therefore is not Kelsenian law. It is instead a description of what actually happens. It could be false, and the law would still be a law (e.g. if the thief was not caught).

A legal system includes general norms such as “Thieves should be imprisoned”, but also specific norms such as ‘This man should be imprisoned.’ A norm with specific application is still a Kelsenian law.

Dependent Norms

An independent legal norm is a norm that prescribes a sanction, e.g. ‘This man should be imprisoned.’ A dependent legal norm is a legal norm that does not itself prescribe a sanction, but is connected to a legal norm that does. For example, the norm ‘This judge is authorised to hear cases’ is valid only insofar as that judge can prescribe/dismiss sanctions, or make decisions that ultimately lead to sanctions

If a norm is not connected to a sanction-prescribing norm, then it is not a Kelsenian law. Such a norm is instead a moral or social norm posited by a legal organ who is not exercising their legal capacity.

All information about dependent norms can be described as a “If X then Y should be” statement (a rule of law), where X is all the conditions stipulated by the dependent norms, and Y is a sanction.

  • A licence to drive can be described as “If (1) a person drives, and (2) they have no licence, then they should be punished.”
  • A law that authorises a judge to preside over a theft case: “If (1) a person is found to have stolen by a judge, and (2) that judge was authorised to preside over the case, then that person should be punished.”
  • A contract to pay $100 in return for a service: “If (1) a person does not pay $100, and (2) that person was required to do so by a legal contract, then that person should be punished.”
  • The Constitution, as applied to theft: “If (1) a person has stolen, and (2) all laws relating to this case were created in accordance with the Constitution, then that person should be punished.”


A taxman, backed up by the State, and a robber backed up by a gun, both demand your money. Both men’s actions have the normative meaning “Give this man your money,” and both of these norms are backed by sanctions. We want a definition of law such that the former is law, and the latter is not.

We can do this by asking which of these two norms is valid. The norm “Give the taxman your money” can be derived from a series of higher norms:

Obey the constitution

Obey laws passed by the legislature

Obey tax law

Obey the tax office and its decisions

Obey the taxman’s authority

Give the taxman your money

If a norm is valid, any norm derived from that norm by imputation will also be valid. The taxman’s norm will be valid under this system, while the robber’s will not. A legal system is therefore a system of coercive, valid norms.

Source of Validity – The Grundnorm

Under Kelsen’s theory, no norm is objectively valid. The ‘source’ of validity therefore must be a norm that is assumed to be valid. Kelsen formalises this assumption through a new object: the basic norm or Grundnorm. The Grundnorm is not a legal norm, it is instead a norm that is assumed to be valid by the legal scientist examining the legal system. A legal norm is then any norm derived from this Grundnorm.

 A Grundnorm refers to a specific constitution or other source of law. For example, the Australian legal system’s Grundnorm is “One ought to obey the Australian Constitution.”

An analogy can be made with science: if we want to say any valid statements about reality, we need to start with something we assume to be valid. Such assumed statements could “experience corresponds to reality” or “things will continue to behave the same way as they have in the past.” Such an assumption is the ‘source’ of the validity of a scientific system.


In order to qualify as a valid legal system, a norm must also be ‘by and large effective’, i.e. the norm must be obeyed most of the time. This means that a legal theorist’s choice of Grundnorm is not arbitrary – we have to choose the Grundnorm that gives validity to the actually effective legal system. We can’t assume that the Grundnorm is ‘Obey Hugh’ because society does not follow this. This is especially important during a revolution – if the old legal order ceases to be effective, either because of a hostile takeover, or just because people stop following the law, then there will be a new legal system and a new Grundnorm.

I talk about effectiveness more here.

Legal Decisions

A law is valid if it was derived from a higher norm. But how does a legal scientist determine whether this derivation was legitimate?

Under Kelsen’s system, there is no objectively right or wrong way to derive a norm from a higher norm, just as there are no objectively valid norms in the first place. All we care about is a legal norm’s validity, and here, the source of validity is whether the person who derived the legal norm was authorised to do so. Therefore, every derivation made by an authorised legal organ is automatically valid. A legal scientist can describe the possible interpretations of a particular law, or the relationships between laws, but they cannot decide which derivation is ‘correct’ – that decision is entirely up to the judge.

It seems to me that there is some wiggle room here, to prevent extreme cases. For example, what if a corrupt judge claims to derive the norm ‘give me money’ from tax law? In this case, the legal theorist could argue that the decision is so unreasonable that it is not derived from the higher norm at all. The corrupt judge’s decision is either invalid and no different from a robbery, or derived from a more general norm of the form ‘This legal organ may posit new norms.’

If a case is successfully appealed, it doesn’t mean that the decision was wrong from the start – it just means that a higher legal organ chose to overturn the decision. For example, if a judge finds a person guilty of murder who was in fact innocent, the judge’s decision is still valid because the judge was authorised to make that decision. Similarly, if the legislature passes an unconstitutional statute, the statute is still valid unless and until it is repealed.

This means that if a decision cannot be appealed, the organ which makes that decision has ultimate legal authority. They can flout the constitution or any other law they choose, and their decision will still be valid. The only considerations that prevent such an organ from disrupting the law this way are non-legal ones, such as the organ’s morality or the organ’s fear of losing office.

This also means that a legal organ’s thinking process, reasoning and arguments behind a decision are not part of legal science. Kelsen admits that these factors are legal in nature, but they instead belong to a different discipline called ‘legal politics’.

I think that this covers all the important parts of the theory. The question is now whether scientific laws can fit into this scheme, and I talk about that here.

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