Distinguishing precedent establishes rules as binding as statute and is comparatively more certain than case

Precedents lay down rules in their rationes, and such rules are binding in later cases whose facts fall within the scope of those rules.

That is, precedents lay down rules (rationes) in their judgments—just as statutes lay down rules in their provisions—and such rules are binding in later cases whose facts fall within the scope of those rules. Statutes and precedents simply employ a different process for laying down rules.

Some later courts have the power to overrule precedents, but all later courts have the power to distinguish precedents, which amounts to a limited power to modify the rule laid down in the precedent case.

That is, some later courts enjoy the power to repeal the rationes of earlier precedents, whereas all courts enjoy a limited power to amend the rationes of a precedent case.

The application of the rule in later cases is determined by the precedent court’s justification(s) for the rule.

That is, the later court determines the application of the precedent’s ratio by reference to the best understanding of how the precedent court meant the ratio to be applied, just as the application of a statute is deferential to the legislator’s supposed purpose in passing the enactment. In both cases the court’s application of the legal rule must be faithful to the intentions of the law-maker.

The function of the doctrine of precedent is to create new legal rules to settle uncertainty in the law, so as to provide guidance to individuals and the courts. That is, the function of the doctrine of precedent is to enable courts to create legal rules to provide guidance for individuals and later courts. The courts’ role is akin to delegated law-makers exercising directed powers: they must decide cases by creating a new rule which best furthers the purpose(s) of the area of law in question.

Statutes and precedents differ, of course, because legislators enjoy far wider discretion in what they can do (and what considerations they can act on), but as to the type of normative standard which they create, they are on a par. The assimilation of precedent to statute facilitates a unified account of law in common law systems: the basic building blocks of legal doctrine are legal rules.