If the discussion about Traditionis custodes has so far concerned the legislative content of the motu proprio, here the text will be considered from a formal point of view as a legal text.
First of all, it should be noted that a law does not require special acceptance by the interested parties to acquire binding force.
However, it must be received by them.
Reception means affirmative acceptance of the law in the sense of “making it your own.”
Only then does the law acquire confirmation and permanence, as the “father” of canon law, Gratian († 1140), taught in his famous Decretum. Here is the original text:
“Leges instituuntur cum promulgantur. Firmantur cum moribus utentium approbantur. Sicut enim moribus utentium in contrariem nonnullae leges hodie abrogatae sunt, ita moribus utentium leges confirmantur ”(c. 3 D. 4).
(Our translation: “Laws are established when they are promulgated. They are confirmed when they are approved by the behavior of those who use them. For as due to the behaviors of users in an opposing direction [against the laws, not following the laws] quite a few laws today have been abrogated, so through the behaviors of the users the laws are confirmed”).
This means, however, that for a law to be valid and binding, it must be approved by those to whom it is addressed. Thus, on the other hand, some laws today are abolished by non-compliance, just as, on the contrary, the laws are confirmed by the fact that those concerned observe them.