Precedent: Why an Earlier Decision Binds a Later Court

Courts decide individual disputes, yet their decisions can govern cases involving strangers years later. That effect is the doctrine of precedent, and its strength varies by tradition.

Certainty is the justification

If similar facts produce similar outcomes, people can order their affairs with some confidence. Predictability is treated as a value in itself.

Equal treatment is the second justification. Two parties in materially identical positions should not receive opposite answers because they appeared before different judges.

The cost is rigidity, and every system operating precedent has mechanisms to relieve it. Those mechanisms are where the interesting work happens.

The binding part is the reasoning

What binds a later court is the legal reasoning essential to the decision, not everything the judgment contains. Observations not necessary to the outcome carry persuasive weight only.

Identifying which is which is a genuine skill and a frequent source of argument. Two lawyers can read the same judgment and extract different principles.

Judgments in appellate courts often contain several opinions reaching the same result by different routes. Working out what the court collectively decided is then harder still.

Hierarchy determines who binds whom

Decisions of higher courts bind lower ones within the same system. Courts at the same level usually treat each other's decisions as strongly persuasive rather than binding.

Decisions from other countries are generally persuasive at most, though they carry real weight in systems sharing a common heritage. That cross-referencing is common in commercial law.

A court is also generally bound by its own earlier decisions, subject to limited exceptions. Those exceptions typically cover decisions made without argument on a relevant point.

Distinguishing is how the system flexes

A court that considers an earlier decision unsuitable can find a material difference in the facts and decline to apply it. This is the ordinary mechanism for development.

Done well, it refines a principle by identifying its proper boundaries. Done poorly, it produces a thicket of narrow exceptions that obscures the rule.

Overruling, by contrast, is available only to higher courts and is used sparingly because it unsettles arrangements made in reliance on the old position.

Codified systems work differently

In traditions built on comprehensive codes, prior decisions are influential but not formally binding. The code is the primary source and consistent lines of decisions interpret it.

The practical gap between the two traditions is narrower than the theory suggests, since consistency is valued everywhere. Which approach applies, and how strictly, is a matter for a lawyer qualified in the relevant system.