8. How many rules of recognition? Certainty and penumbra in the rule of recognition

Finally, we still have to treat the question of the unity of the rule of recognition and the possibility of zones of penumbra in the rule of recognition itself.

8.1. So far, we have implicitly assumed that every legal system has one and only one rule of recognition (which provides the criterion for the system's identity).

"[T]here is no reason to suppose that every legal system has just one rule of recognition. It may have more. Imagine a legal system in which no valid law makes custom or precedent a source of law, but in which, nevertheless, both custom and precedent are sources of law. It follows that the criteria for the validity of laws created by custom or precedent are determined by rules of recog­nition [...] But we should not assume that there is just one rule of recognition rather than two — one relating to each source of law — simply because the system must contain means of resolving conflicts between laws of the various sources.

Here, Raz presents two different cases: One of them is the case where there is only one rule of recognition which, however, is discovered to have gaps when one tries to determine which is the supreme criterion of legal validity and which is the subordinated one. That is possible, but, it seems, only in the con­text of an embryonic legal system; in any minimally developed system, it seems difficult to imagine that the question has never arisen before and has not, therefore, been given a generally accepted solution. And if it has arisen, and the judiciary or, in general, the respective legal community, instead of having created a generally accepted solution for it, is divided on a question of such central importance for the identification of valid law, then it seems that one cannot speak of one single legal system; rather, we would then have two sys­tems competing with each other. The second case presented by Raz is that of two different rules of recognition, stipulating the same order of relative sub­ordination and primacy between the two sources each one of them, respec­tively, refers to. But in that case, there seems to be no relevant difference to Hart's thesis of the unity of the rule of recognition: Because the assertion a) that a legal system has two rules of recognition each of which indicates — in a mutually consistent way — the hierarchic position of the ultimate source it refers to apparently means just the same, only formulating it differently, as the assertion b) that the legal system in question has one unique rule of recognition which indicates the rank order of the two ultimate sources it refers to.

8.2. Thus, the controversy over that question seems to be highly artificial. Be­sides, it only makes sense with respect to a legal system having more than one ultimate source. With respect to a system like the Spanish one, where there is no other ultimate source than the Constitution, the controversy cannot even be stated. More interesting for us is the question about the existence of indetermi- nacies, or zones of penumbra, in the rule of recognition. According to Hart, the (at least, potential) presence of zones of penumbra cannot be eliminated from any legal norm, and this also affects "the rule of recognition specifying the ulti­mate criteria used in the identification of the law" (Hart 1994, 123), which also "has its 'penumbrae' area as well as its 'firm', well-settled core" (Hart 1983a, 360). In the English case, that zone of penumbra affects the way in which its central pillar, that is, the doctrine of parliamentary sovereignty, is understood. Here, one must choose "between a continuing omnipotence in all matters not affecting the legislative competence of successive parliaments, and an unre­stricted self-embracing omnipotence the exercise of which can only be enjoyed once" (Hart 1994, 149). Thus, the validity of a possible law of parliament that would imply that some matter is irrevocably subtracted from the future compe­tence of the parliament itself is controversial.^[81] In the Spanish case, we think that the main zone of penumbra exists around the fact that by referring to the Constitution the rule of recognition refers to a source which not only claims the obligatoriness of the prescriptions issued by the authorities that source itself institutes, but also of an entire set of values and principles it contains. The possibility of conflicts between what we could call the principle of obedience to the authorities instituted by the Constitution — which can be seen as the most general principle, from which other, more specific principles, like those of legality, of the vinculation of ordinary courts to the interpretation of the Consti­tution given by the Constitutional Court, etc., derive — and the substantive principles contained in the Constitution cannot be excluded.

8.3. Does it make sense to say that all those who accept, for example, one and the same constitution as the supreme legal source share the same rule of recog­nition, even if they then diverge on the interpretation of that constitution? Could one not say that different norms (rules of recognition) are underlying one and the same sentence — of the type 'One ought to obey the constitution and the norms issued or received in accordance with it'? We think that the answer to that question depends on the extent of the difference in the propositional con­tent the different sides attribute to such a sentence.