Once the determination has been validly made and meets the criteria of validity established by or under the constitutional law of the legal system concerned, it modifies the existing legal situation by introducing a new or amended rule of law and a rule of law. The new or modified rule of law gives judges, other public servants and citizens a new or modified reason to act (or to refrain). The fact that the new or amended rule depends on the de facto social source constituted or used by the act of determination does not mean that a normative reason (a « should ») flows illogically from a mere fact (an « is »). On the contrary, the new or modified rule is normative, directive and (when this is its legal meaning) convincing, because this social fact can be the second premise of a practical syllogism, the first premise of which is normative: « There should be a maternity in this city », « People should be protected from murderous assault », « People should be required to participate in the public expenditure of appropriate government functions », « Victims of personal injury, theft, breach of contract, negligence, etc. should be compensated », « Road traffic should be regulated to reduce harmful collisions », etc. The moral normativity of the principle is reproduced in the more specific rule created by the determination, although the latter is not a consequence of the first. Legal norms are phrases of practical reason that can be understood as guidelines in the considerations of individual legal subjects in the sense of judgment, choice (decision) and action (including chosen tolerance). A sound legal theory will thus have an integrated and critical understanding of the structure of the action chosen, in particular the relationship between the intention of the ends, the presumption of means, the dual character of almost all ends as well as means and almost all means and ends, and the need and normal possibility of freely choosing between options that involve advantages and disadvantages or immeasurable promises (incompletely). comparable) (Finnis 1997) with the advantages and disadvantages of alternative options. Such an understanding will clarify the often somewhat crude representations given in criminal law dogmatics (case law and manuals) of actus reus and mens rea, which often fail to distinguish action as physically or conventionally delimited conduct and action as execution of the choice of an option, i.e. a proposition that receives a privileged description in the deliberations of the acting subject. The difference between intentional or chosen means (or ends) and foreseeable or even fully foreseeable effects (« side effects ») is psychologically and morally real, as is the resulting difference between moral and presumed legal norms that apply to intended and unintended effects.

But it is often distorted by a simplistic legal dogmatic opposed to the (very real) risk that defendants will have excuses for what they had in mind. What matters, and can often be inferred despite escapes, is the description of the action under which the chosen conduct was attractive to the defendant in its actual considerations (as opposed to the rationalizing descriptions of the action that were used to better represent that motivation). The author`s insistence on classifying these principles of legality as « morality » is a source of confusion for him and his readers. The decisive objection to calling these principles of good legal morality, despite the « internal » characterization, is that it creates confusion between two concepts that must be separated: the concepts of intentional activity and morality. Poisoning is undoubtedly a useful activity, and reflections on its purpose can show that it has its internal principles. (« Avoid poisons, no matter how deadly, if they make the victim vomit. But to call these principles of the art of the poison mixer « the morality of poisoning » would only blur the distinction between the notion of effectiveness for a purpose and definitive judgments about the activities and purposes that morality treats in its various forms (Hart 1965, pp.