When the rule changed, what were you supposed to do?

Every organisation eventually has to defend a decision it made in the past. Not against today's rules, but against the rules that applied on the day it acted.

That is a harder question than it sounds. Rules change. They get amended, consolidated, replaced, reinterpreted. The version you find today is rarely the version that governed you then. And the person asking is usually an auditor, a regulator, a court or a counterparty, none of whom will accept that this is what the website says now as an answer.

Most organisations solve this with people. Someone remembers. Someone kept a PDF. Someone reconstructs it. It works until the person leaves, the PDF is lost, or the stakes are high enough that memory is not evidence.

Grundnorm exists for that moment.

What it does

You give it two things: an identifier for a rule, and a date. It returns what that rule meant on that date, as a record that has been decomposed into its component obligations, ratified by the authorities that have standing to say so, and sealed so that anyone can confirm it has not changed since.

Not a summary. Not a best guess. A specific, dated, attributable statement of meaning that survives the person who produced it.

And it does one more thing that sounds small and is not: when it does not know, it says so, and it can demonstrate that its silence is real rather than convenient.

Why it is called Grundnorm

The name is borrowed, and anyone who has studied jurisprudence will recognise it. In Hans Kelsen's Pure Theory of Law, every legal norm draws its validity from a higher one. The chain has to end somewhere, and the last link is the Grundnorm, the basic norm. Kelsen's point about it is precise: it is presupposed rather than enacted. It is not posited by anyone's act of will, and it is not derived from a higher norm, because there is none above it. You assume it in order to close the system.Sources: Kelsen, On the Basic Norm (1959) · Stanford Encyclopedia: the Pure Theory of Law

Kelsen went further late in his life. Having spent decades calling the basic norm a hypothesis, in 1964 and again in the posthumous General Theory of Norms he reclassified it as a fiction in the sense of Vaihinger's philosophy of as-if, and said plainly that such a fiction is not merely contrary to reality but contains a contradiction within itself. Whether that was a genuine reversal is still argued over. What is not in doubt is that the foundation of the most rigorous positivist account of law is something its own author ended up describing as a useful fiction.

Which is exactly why the name fits, and not in the way it first appears. We did not name this after the bedrock that cannot be questioned. We named it after the one thing in Kelsen's system that has to be taken on trust, and then built the opposite. Kelsen's basic norm is presupposed. Ours is a record. Where he had to assume, this returns the bytes that were signed, and you check them on your own machine without asking us. And where it cannot establish authority, it says so in the answer rather than presupposing it.

Three properties that decide whether you can rely on it

It gives the same answer every time. The same question on the same date returns the same result, today and in five years. There is no model deciding in the moment, so there is nothing to drift. Two people asking the same question get the same answer, which is the minimum requirement for anything you intend to cite.

You do not have to trust the people who run it. Every answer carries what is needed to confirm it independently, on your own machine, with software you control. This is the part that most surprises people: the honest position for a source of truth is not trust us, it is you never have to. A record that can only be checked by asking the same party again has not been checked.

It refuses, in two different ways, and both are features. If it does not hold a rule, it says so plainly instead of producing something plausible. And when two competent readings of the same provision genuinely disagree, it does not pick a winner to look confident. It records the disagreement and hands it to whoever has the authority to settle it.

That last one is the heart of the thing. A system that always answers is a system that is sometimes wrong without telling you. Most of the cost of automation in regulated work is not the wrong answers. It is the wrong answers delivered with the same confidence as the right ones.

Why this is not only about law

Law is where the problem is sharpest, because the consequences are formal and the adversary is a court. But the shape of the problem is not legal at all. It appears wherever a decision must be defended later against a rule that has since moved.

A bank justifying a capital treatment against the prudential rule in force at the reporting date. An insurer interpreting a policy clause as it read when the claim arose, not as it reads after the last endorsement. A hospital showing that a treatment followed the clinical protocol current on the day of care. A manufacturer proving conformity with the version of a technical standard that applied when the product was certified. A public buyer demonstrating that a tender followed the procurement rules at the date of publication. An employer handling a dispute about conduct governed by an internal policy that has been revised twice since.

None of those are lawyers looking things up. They are ordinary operations that become expensive precisely when someone asks, months or years later, what the rule said at the time.

And there is a newer case that did not exist five years ago. AI systems are now making or supporting decisions inside regulated processes, and they are being asked to show their work. A model that cites a rule is only as defensible as the source it cited. Grundnorm gives that kind of system something to point at that a regulator can independently re-check, which is a different and much stronger position than a confident sentence with a footnote.

Who it is for

Institutions that publish rules and want their meaning to be citable rather than merely available. Regulated organisations that must evidence compliance against a moving target. Standards bodies. Large organisations whose internal policy has the force of a rule inside their own walls. And builders of AI systems that operate in places where being wrong quietly is not an acceptable failure mode.

The common factor is not the sector. It is that the organisation will, at some point, have to prove what a rule meant on a specific day, to someone who is not inclined to take its word for it.

How it is delivered

Grundnorm is not a subscription you sign up for and start using. It is a platform that is built to a specification.

Each deployment is different in the ways that matter: which body of rules it covers, which sources it draws from, which institutions hold the authority to ratify a meaning, what the deployment commits to covering and what it explicitly does not, and what standard of correctness the organisation and its own experts agree on before anything goes live. Those are decisions belonging to the engagement, not defaults we hand over.

That also means the work starts with a conversation about your rules, not with a sign-up form.

One thing we will not tell you

We do not publish a single accuracy figure, and we are not going to.

A number measured on one body of rules, in one language, under one legal tradition, tells you nothing about another. Averaging across them produces a figure with no referent, which is worse than no figure at all because it sounds like information. Correctness is established for a specific deployment, against that organisation's own material, judged by that organisation's own experts.

We would encourage the same scepticism toward anyone else's single number, including ours if you ever see one.

The short version

Anyone can tell you what a rule says today. The question that costs money is what it meant on the day you acted, and whether you can still prove it.

That is the question Grundnorm was built to answer.Sources: See how it works