The disregard of a precedent assumes two distinct forms, for the court to which it is cited may either overrule it, or merely refuse to follow it. Overruling is an act of superior jurisdiction. A precedent overruled is definitely and formally deprived of all authority. It becomes null and void, like a repealed statute, and a new principle is authoritatively substituted for the old. A refusal to follow a precedent, on the other hand, is an act of co-ordinate, not of superior jurisdiction. Two courts of equal authority have no power to overrule each other’s decisions. Where a precedent is merely not followed, the result is not that the later authority is substituted for the earlier, but that the two stand side by side conflicting with each other. The legal antinomy thus produced must be solved by the act of a higher authority, which will in due time decide between the competing precedents, formally overruling one of them, and sanctioning the other as good law. In the meantime the matter remains at large, and the law uncertain.
§ 66. Precedents Constitutive, not Abrogative.
We have already seen the falsity of the theory that all precedents are declaratory. We have seen that they possess a distinct and legally recognised law-creating power. This power, however, is purely constitutive and in no degree abrogative. Judicial decisions may make law, but they cannot alter it, for where there is settled law already on any point the duty of the judges is to apply it without question, and they have no authority to substitute for it law of their own making. Their legislative power is strictly limited to supplying the vacancies of the legal system, to filling up with new law the gaps which exist in the old, to supplementing the imperfectly developed body of legal doctrine.
This statement, however, requires two qualifications. In the first place, it must be read subject to the undoubted power of the courts to overrule or disregard precedents in the manner already described. In its practical effect this is equivalent to the exercise of abrogative power, but in legal theory it is not so. The overruling of a precedent is not the abolition of an established rule of law; it is an authoritative denial that the supposed rule of law has ever existed. The precedent is so treated not because it has made bad law, but because it has never in reality made any law at all. It has not conformed to the requirements of legal efficacy. Hence it is that the overruling of a precedent, unlike the repeal of a statute, has retrospective operation. The decision is pronounced to have been bad ab initio. A repealed statute, on the contrary, remains valid and applicable as to matters arising before the date of its repeal. The overruling of a precedent is analogous not to the repeal of a statute, but to the judicial rejection of a custom as unreasonable or as otherwise failing to conform to the requirements of customary law.
In the second place, the rule that a precedent has no abrogative power must be read subject to the maxim, Quod fieri non debet, factum valet. It is quite true that judges ought to follow the existing law whenever there is any such law to follow. They are appointed to fulfil the law, not to subvert it. But if by inadvertence or otherwise this rule is broken through, and a precedent is established which conflicts with pre-existing law, it does not follow from this alone that this decision is destitute of legal efficacy. For it is a well-known maxim of the law that a thing which ought not to have been done may nevertheless be valid when it is done. If, therefore, a precedent belongs to the class which is absolutely authoritative, it does not lose this authority simply because it is contrary to law and ought not to have been made. No court, for example, will be allowed to disregard a decision of the House of Lords on such a ground; it must be followed without question, whether it is in harmony with prior law or not. So also with those which are merely conditionally authoritative. We have already seen that error is only one of two conditions, both of which are requisite to render allowable the disregard of such a precedent, and in this respect it makes no difference whether the error consists in a conflict with law or in a conflict with reason. It may well be better to adhere to the new law which should not have been made than to recur to the old law which should not have been displaced.
§ 67. Grounds of the Authority of Precedents.
The operation of precedents is based on the legal presumption of the correctness of judicial decisions. It is an application of the maxim, Res judicata pro veritate accipitur. A matter once formally decided is decided once for all. The courts will listen to no allegation that they have been mistaken, nor will they reopen a matter once litigated and determined. That which has been delivered in judgment must be taken for established truth. For in all probability it is true in fact, and even if not, it is expedient that it should be held as true none the less. Expedit reipublicae ut sit finis litium. When, therefore, a question has once been judicially considered and answered, it must be answered in the same way in all subsequent cases in which the same question again arises. Only through this rule can that consistency of judicial decision be obtained, which is essential to the proper administration of justice. Hence the effect of judicial decisions in excluding the arbitrium judicis for the future, in providing predetermined answers for the questions calling for consideration in future cases, and therefore in establishing new principles of law.
The questions to which judicial answers are required are either questions of law or of fact. To both kinds the maxim, Res judicata pro veritate accipitur, is applicable. In the case of questions of law, this maxim means that the court is presumed to have correctly ascertained and applied the appropriate legal principle. The decision operates, therefore, as proof of the law. It is, or at all events is taken to be, a declaratory precedent. If the law so declared is at all doubtful, the precedent will be worth preserving as useful evidence of it. But if the law is already clear and certain, the precedent will be useless; to preserve it would needlessly cumber the books of reports, and it will be allowed to lapse into oblivion.
In the case of questions of fact, on the other hand, the presumption of the correctness of judicial decisions results in the creation of new law, not in the declaration and proof of old. The decision becomes, in a large class of cases, an original precedent. That is to say, the question thus answered ceases to be one of fact, and becomes for the future one of law. For the courts are now provided with a predetermined answer to it, and it is no longer a matter of free judicial discretion. The arbitrium judicis is now excluded by one of those fixed and authoritative principles which constitute the law.
For example, the meaning of an ambiguous statute is at first a pure question of fact. When for the first time the question arises whether the word “cattle” as used by the statute includes horses, the court is bound by no authority to determine the matter in one way or the other. The occasion is one for the exercise of common sense and interpretative skill. But when the question has once been decided, it is for the future one of law and no longer one of fact; for it is incumbent on the courts in subsequent cases to act on the maxim Res judicata pro veritate accipitur, and to answer the question in the same way as before.