What Is Precedent? How One Judge's Decision Binds the Next
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When a judge in England decides a case, the decision does not end with the parties. If it turns on a point of law, the reasoning becomes a rule that every lower court must apply to the next case with the same facts, and the rule stands until a higher court overturns it or Parliament changes it. That is precedent, or stare decisis, to stand by things decided, and it is the mechanism by which the common law of England, the United States, Canada, Australia, India and forty other countries has been made, not by legislatures alone but by the accumulated rulings of judges over eight hundred years.
The idea
Like cases should be decided alike. That is the principle, and it serves several ends at once: fairness, since two people in the same position should get the same answer; predictability, since a person can know what the law is before acting; efficiency, since a settled question need not be argued again; and restraint, since a judge who is bound by earlier decisions cannot simply rule as they please. The common law grew from the practice of the royal courts after the twelfth century of recording their decisions and referring to them, and the law of contract, tort, property and crime in England was built almost entirely that way before Parliament began to codify it. In civil-law countries such as France and Germany, where the law is in codes, earlier decisions are consulted and respected but do not formally bind, and the difference is the main divide between the world's legal families.
What binds
Not everything a judge says is precedent, and the doctrine has rules for sorting it:
- •The ratio decidendi, the reason for the decision: the legal principle necessary to the result, which is what binds
- •Obiter dicta, things said by the way: observations, hypotheticals and remarks not needed for the result, which persuade but do not bind
- •Hierarchy: a court is bound by courts above it in its own system and by its own earlier decisions in most cases; the Supreme Court in Britain and the United States can depart from its own precedents, and does so rarely
- •Jurisdiction: decisions of courts in other common-law countries are persuasive, and the courts of Australia, Canada and England cite each other constantly, but bind nothing
- •Facts: a precedent applies only where the material facts are the same, and the argument in most cases is about whether they are
Distinguishing and overruling
A precedent that a court does not wish to follow can be escaped in two ways. Distinguishing is the everyday one: the court finds that the facts before it differ in some material way from the earlier case, so that the rule does not apply, and the skill of the advocate is in making the difference matter or not. Overruling is rarer and can only be done by a court high enough: the earlier decision is declared wrong and ceases to be law, as the House of Lords did in 1966 when it announced that it would no longer be bound by its own decisions, and as the American Supreme Court did in 1954 when it overruled the doctrine of separate but equal, and in 2022 when it overruled its 1973 abortion ruling. Overruling is deliberately hard, because a law that changes with the judges is no better than none, and the arguments about when a court should overrule and when it should defer to what was decided are the arguments about what a court is for.
How a rule is found
The famous cases are the ones that made rules from nothing. Donoghue v Stevenson in 1932, the snail in the ginger beer, created the modern law of negligence from a single principle about neighbours; Carlill v Carbolic Smoke Ball in 1893, about an advertisement promising a reward to anyone who caught flu after using the product, settled when an advert is a contract; Marbury v Madison in 1803 established that American courts could strike down laws. Each began as one dispute between two parties, and each was reasoned in a way that later courts found applied to thousands. Law reports, the published records of decisions with their reasoning, are the common lawyer's library, and the citation of a case by name, year and page is how a rule is identified. Since the 1990s the reports have been online, and the practice of citing unreported decisions, once forbidden, has become the norm.
The argument about it
Precedent is praised for stability and blamed for rigidity, and both are right. A system that follows past decisions preserves rules that were made for a different society, and the common law's treatment of married women, of servants and of the poor persisted through precedent long after opinion had moved; a system that does not follow them puts every rule at the mercy of the next judge. The compromise the common law reached is that lower courts follow, higher courts may reconsider, and legislatures may override, and in practice the three work together, with judges filling the gaps that statutes leave and Parliament correcting the judges when it disagrees. Whether unelected judges should make law at all is the question the doctrine cannot settle, because it is the question of whether the common law should exist, and it has been answered in practice by eight centuries of doing so.
The takeaway
Precedent is the common-law rule that a court must follow the legal reasoning of earlier decisions by courts above it, and usually its own, so that like cases are decided alike and the law is built case by case from published judgments. Only the reason necessary to the decision binds, remarks made in passing persuade, a court may distinguish a precedent on the facts or, if senior enough, overrule it, and the doctrine trades some rigidity for the predictability and fairness that make a body of judge-made law possible.