Kelsen establishes three requisites for a legal norm to be said to be valid. The first one is its belonging to an existing legal system, that is its legality. The second one is its containing of a sanction or connection to other norm which contains a sanction, that is its coercion. The third one is its being obeyed, that is its efficacy. Kelsen also states that his pure theory of law is formal, which means that it admits of any content to be law and its requisites are completely void of content.
In the case of the third requisite for the validity of legal norms, that is efficacy, we can challenge Kelsen’s belief that such requisite is indeed formal by reasoning as follows: a) if a requisite is to be formal, it must make no distinction among different possible contents; b) if the requisite of efficacy is to be formal, then efficacy must make no distinction among different possible contents of norms; c) if efficacy is to make no distinction among different possible contents of norms, then norms with every possible content must be able to be efficacious. But c) is not only an empirical statement (therefore, not much of a candidate for being formal), but it is also a glaringly false one. Therefore, efficacy is not a formal requisite.
We can go one step further and connect the issue of efficacy with that one of acceptability. It is obviously true that one of the many possible reasons for a norm to be inefficacious is the addressees’ rejection of its content, that is its lack of acceptability. If at least in some cases of inefficacy, the norm is inefficacious due to its unacceptability, then at least in some cases inefficacy will be an issue that depends on the content of the norm. Well, an issue depending on the content of the norm cannot, by definition, be a formal one. Therefore, efficacy is not a formal requisite.
This challenge could be met with the following response: If the efficacy of the norm were in any measure depending on the acceptance of its content, then it would not be a formal requisite. But in Kelsen’s theory, the efficacy of a norm is obtained by means of the sanction.
Kelsen denies that a sanction alone can bring about efficacy for a norm of behavior, but, even when it does not, it creates a second kind of efficacy for a norm, that is the efficacy of its sanction. Then, even when the content of a norm of behavior were so unacceptable as to turn that norm inefficacious in the first sense (people not acting according to the norm commandment), the application of its sanction to the disobeying addressee would still turn it efficacious in that second sense (people who do not act according to the norm commandment being sanctioned).
However, it would only postpone the problem. The sanction would only be a solution for the problem of inefficacy if the sanction itself could never be inefficacious. But sanctions also have contents, and their contents can also be unacceptable. If at least in some cases the unacceptability of a norm entails its inefficacy, then at least in some cases sanctions that are unacceptable would also be inefficacious.
It would happen not only in cases where sanctions are inhumane or disproportional, but also in cases where the sanction punishes the disobedience to an unacceptable norm of behavior. If the behavior commanded by the norm is unacceptable, then a sanction punishing the disobedience to such norm would also be unacceptable.
If in some cases unacceptable norms of behavior can become inefficacious, then the unacceptable sanctions punishing those who disobey such norms cannot wait for a better fate. Otherwise we would be counting on totally cold-hearted sanction enforcers, capable of applying any sanction no matter how unacceptable it is.
But, if we could appeal to fictional beings like that, we would have no reason not to appeal instead to perfectly obedient addressees, capable of obeying norms of behavior no matter how unacceptable they are. Fictions could have solved our problems many steps earlier.
If, however, we are not fictionalizing, then the assumption that all sanction enforcers are totally cold-hearted is, to say the least, very unlikely to be true.
Thus, sanctions would also depend on their efficacy, which would also in at least some cases depend on their content; therefore, efficacy, with or without sanction, would keep not being a formal requisite.
If that is right, we can not only come to the conclusion that efficacy cannot be a formal requisite, but we can invert that conclusion against Kelsen’s purposes and say that, introducing efficacy as a requisite for validity, Kelsen sheltered a material wolf covert with sheep’s formal clothing. For saying that every content can be valid law, but, in order to be valid law, that content must be efficacious is tantamount to saying that, as not every content can be efficacious, not every content can be valid law. And any theory that recognizes that is not a formalistic theory anymore.