Everyone has heard the word. Almost no one explains what it actually means. A court decision is not just a story about someone else’s dispute. It may be the rule that applies to yours.
English law is built on a principle that has been operating for centuries: stare decisis. In Latin, it means roughly “stand by what has been decided.”
The logic is straightforward. If a court has once resolved a dispute and explained why it reached a particular conclusion, that explanation becomes the rule for similar disputes in the future.
A judge does not simply declare who won and who lost. He sets out the reasoning in detail. That “why” — the legal logic recorded in the judgment — is called the ratio decidendi. It is the ratio, not the outcome or the facts of the dispute, that becomes the binding part of the precedent: the line of reasoning by which the court arrived at its conclusion.
When a similar situation arises tomorrow, the judge opens the old decision: this question has already been decided, so the same rule applies. This is why English judgments are long. Every judge understands that he is writing not only for the two parties in front of him, but for everyone who comes after. And that reasoning may remain in force for fifty years. Or longer.
Precedents operate by hierarchy. The higher the court, the greater the weight of its decision.
The High Court — significant. The Court of Appeal — more so. The Supreme Court — final.
Until 2009, the final word came from the House of Lords — a real one, with lords, later replaced by the Supreme Court. Apparently the lords grew tired.
A lower court cannot simply ignore a decision from a higher one, even if the judge personally believes the earlier case was wrong. The system depends on exactly this: like cases must be decided alike. Otherwise the law becomes a lottery — only more expensive and considerably less exciting.
In arbitration, precedent operates as a powerful argument — but not as a mandatory rule.
Parties arrive with a bundle of decisions and say: a similar situation was decided this way, so the same result should follow here. Arbitrators assess whether the earlier dispute is genuinely comparable, how persuasive the reasoning is, and how much weight the argument deserves. It can carry considerable force, but it is not automatically binding.
In court, the position is stricter. Where a higher court has ruled on a comparable legal question, a lower court is bound to follow. The judge may argue about applicability, distinguish the facts, look for differences between the cases — but if the precedent genuinely fits, there is no going a different way.
In arbitration, you persuade with precedent. In court, you are bound by it.
A seller and a buyer agreed a deal by messenger. They wrote “booked” and “super.” The full contract, including the arbitration clause, was never signed.
The buyer commenced arbitration. The arbitrators accepted jurisdiction: they decided that the arbitration clause was implied by trade custom.
The High Court set that decision aside. It held that trade custom must be proved by documents and expert evidence — not by two traders saying it is obvious to everyone.
“Everybody knows” is not evidence. It is a kitchen conversation.
That decision is now a reference point for similar disputes. The next time someone arrives with a comparable story, the judge will open this case — and arguing against it will be considerably harder.
Precedent is not permanent — but it can only be changed by a court of the same or higher level.
When a new case arrives, the Court of Appeal or the Supreme Court may look at the question differently and say: the earlier decision missed an important point, so the rule is now different.
A High Court decision carries weight, but the Court of Appeal can change it. A Supreme Court decision is as close to final as English law gets. Theoretically it can be overturned — in practice, it is a very long journey.
When people say “according to established case law,” this is what they mean: not someone’s opinion, not a general sense of how things are done, but court decisions that may be binding on similar disputes.
When a case note says “the House of Lords held” or “the High Court decided,” that is not history about someone else’s argument from long ago. It is a rule that may be applied to your dispute, if it turns out to be similar enough.
Precedents matter not as elegant legal theory, but as the actual rules of the field you are working on.