Robert Alexy dies: the man who gave law back its claim to correctness

Robert Alexy died on Saturday 5 September. He was eighty years old.

Four days later, on 9 September, he would have turned eighty-one.

In legal philosophy some figures talk about law. Others change the question “what is law?” itself.

Alexy belonged to the second group.

And to remember him only as “the theorist of the proportionality test” — which is how much of the world will remember him today — is to salute a method while missing the obstinacy behind it.

Law and philosophy, read together#

He was born in Oldenburg in 1945. At the University of Göttingen he read law and philosophy together, and that joint reading determined everything that came after.

In philosophy his teacher was Günther Patzig: a scholar of Aristotelian logic and of ethics, formed in the analytic tradition. In law it was Ralf Dreier, the foremost critic of positivism in German legal theory.

The intersection of those two names explains Alexy's entire programme. The analytic demand for precision, joined to a refusal to give up the moral dimension of law.

In 1976 he took his doctorate with Theorie der juristischen Argumentation (A Theory of Legal Argumentation). In 1984 he completed his Habilitation with Theorie der Grundrechte (A Theory of Constitutional Rights). Both are now counted as modern classics.

He spent the greater part of his academic life at the University of Kiel. In 2002 he was elected to the Göttingen Academy of Sciences; in 2010 he received the Order of Merit of the Federal Republic of Germany.

But that is the record of a career. The real matter lies elsewhere.

The great quarrel of the twentieth century#

The argument Alexy entered was the oldest quarrel in legal philosophy.

Positivism holds that whether a norm is law has nothing to do with whether its content is just. Kelsen's hierarchy of norms, Hart's rule of recognition — both ground law in social and institutional facts. An unjust statute is an unjust statute; it does not thereby stop being one.

That position has a moral virtue which is usually forgotten: separating law from morality is what makes it possible to criticise law. Being able to say “this is law, but it is unjust” is a resource.

Alexy set himself against it — though not as a crude natural lawyer.

The dual nature of law#

This is Alexy's most original thesis, and it repays careful reading.

Law, as he saw it, is a two-dimensional institution.

On one side it is factual: posited, in force, backed by sanction, institutional. This is the dimension the positivists see, and Alexy does not deny it.

On the other it carries an ideal dimension: law necessarily raises a claim to correctness about itself.

This second point is the critical one. Alexy's claim is not that law ought to be moral. His claim is that law, by its very structure, asserts that it is right.

Consider a court judgment. It does not merely announce that this is how things shall be. It gives reasons. To give reasons is to say that the decision is defensible. No judge writes at the foot of a ruling that the ruling is arbitrary — were one to do so, the judgment would contradict itself.

Alexy called this a performative contradiction. Law cannot abandon the claim to correctness, because the moment it does it annuls itself.

From here one reaches Radbruch's famous formula: when a norm is intolerably unjust, it is no longer law. Alexy rebuilt that formula with the tools of contemporary analytic philosophy.

It should be said that he set the threshold high. His thesis is not that a statute one finds unfair ceases to be law; the threshold is reserved for extremes that shake the conscience of humanity.

Rules are one thing, principles another#

Alexy's most durable technical contribution is this distinction.

Rules are definitive commands: they either apply or they do not. Stop at a red light. If two rules conflict, one is invalid or an exception is recognised.

Principles are optimisation requirements. A principle is a demand to be realised to the greatest extent legally and factually possible.

Freedom of expression is a principle. The right of personality is a principle. Public security is a principle.

When two of them collide, neither is invalidated. The question asked is which of them gives way, and how far, in the case at hand.

Proportionality: structure against arbitrariness#

Out of this comes the method that spread across the world. A limitation on a right is tested in three stages.

Suitability. Does the measure genuinely serve the aim pursued?

Necessity. Could the same aim be reached by a means that restricts the right less? If it could, the measure is unnecessary.

Proportionality in the narrow sense. Is there a reasonable balance between what is given up and what is gained?

Alexy tried to formalise the final stage, proposing a structure he called the weight formula (Gewichtsformel): the intensity of the interference with one principle, the concrete weight of the competing principle and the reliability of the empirical assumptions are taken into account together.

The formula attracted a great deal of criticism, much of it the charge that it turns legal reasoning into arithmetic. Alexy's defence was plain: the formula does not produce numbers; it shows which questions a judge is obliged to ask.

The aim, that is, is not calculation but visibility. If a judge says he is balancing, let him be compelled to set out openly what he is weighing against what.

The real matter: giving reasons#

To read Alexy through proportionality alone is to miss the question that drove him.

The question was this:

Why does a judge expect us to accept his decision as correct?

For Alexy, the answer could not be that he is the authority who decides.

The answer had to be the reasons.

This is why his theory of legal argumentation is a relative of Habermas's discourse ethics: law is an institutionalised argument. A ruling is legitimate not because it has issued from a court but because it can be rationally defended.

The kinship with the social ontology set out in our file on John Searle this week is striking. Searle shows that institutions are made through linguistic acts; Alexy adds that those institutions are obliged to justify themselves.

The objections#

An honest portrait must set down the other side as well.

The indeterminacy objection. How much of a constraint does balancing really impose on a judge? For critics, proportionality may supply arbitrariness with a technical covering rather than prevent it: the judge picks the outcome first and fills in the formula afterwards.

The incommensurability objection. Can freedom of expression and public order be weighed in a common unit? If they cannot, balancing is no more than a metaphor.

The democracy objection. Do constitutional courts, by way of proportionality, acquire an unbounded power of review over the political choices of elected assemblies?

The fiercest version of these objections comes out of the legal realist tradition. As we explain in our file on Brian Leiter, also published today, realists hold that judicial decisions are to be explained not by reasons but by psychological, ideological and social factors.

The coincidence is not so strange: among the first sources to report Alexy's death was the blog of Leiter, that tradition's most influential contemporary defender.

Today's questions#

Alexy's death does not close his questions. Quite the reverse.

Can a decision made by an algorithm be legally justified? On Alexy's criterion a decision is legitimate in virtue of its reasons; can a system whose reasons cannot be examined decide anything at all?

How is the proportionality test to be applied to a content moderation rule that affects hundreds of millions of people?

Where is the limit on liberties drawn in the name of security — and who draws it?

What should constitutional review do when the will of the majority violates fundamental rights?

And underneath all of them:

Is everything a state does law?

Alexy's entire body of work was built to show the danger of a comfortable “yes” to that question.

If his legacy can be pressed into a single sentence, it is this:

Law is not the power to use force; it is the obligation to justify oneself.

---

Robert Alexy was born in Oldenburg on 9 September 1945 and died on 5 September 2026. In Turkish: Hukuki Argümantasyon Kuramı · Anayasal Haklar Teorisi · Hukukun Kavramı ve Geçerliliği.

We examined Alexy's extraordinary influence in Latin America, and the argument it has provoked, in our file in the World section.