USI. — It is a traditional opinion (though not without controversy) that customs (understood in a generic sense as equivalent to usages) are sources of objective law. In normative systems of distant epochs and even in some contemporary systems of a traditionalistic formation, they have had and retain great importance, although they cannot be considered (as is commonly held) the primary source of law; for if the constitutive element of custom is antiquity, one would have to suppose that before custom there existed a society without law: a clear contradiction, since law is immanent in every social order.
One can only admit that custom may be (not that it necessarily is) the first source containing general and abstract norms. Another constitutive element of custom or usage, according to common doctrine—but also contested—is the *opinio iuris necessitatis* referable to the collectivity or social aggregate. Thus, a formation is produced that may be described as decentralized or popular, in contrast to the centralized or authoritarian nature of legislative sources.
The importance of customs has declined in modern times for various reasons, which can be summarized in two: first, the growing intervention of the State, especially through its legislative organs, in regulating intersubjective relations, thereby limiting the autonomy of individuals; second, the weakening of a factual presupposition in the formation of usages, namely the uniformity over time of the regulated relations, which in modern business practice can undergo rapid modifications and evolutions. Nor is it always accurate to claim that customs better achieve a fair balance of conflicting interests than laws, since at times they may instead reflect the dominance of one group over others, no longer corresponding to changed social conditions and thus correctable precisely through legislative norms or even through collective agreements or contracts in economic or labor matters in particular. All such norms, even when reduced to writing, have, in comparison with customary ones, a higher degree of precision and certainty, as well as a greater promptness of expression within certain limits.
Even in international law, custom, while retaining notable importance, sees its sphere of applicability delimited as treaties and conventions multiply.
To delimit does not mean to annul, and in fact, limiting ourselves to Italian law, even in the new private law codes one finds provisions that refer to usages (a term now preferred by the legislator) or “normative usages” (legal usages), as much of the doctrine calls them, to distinguish them from the so-called “negotiated usages” (of business, interpretative, etc.), which are established by convention and technical (or factual) in nature, followed out of social convenience or practical utility, sometimes with even public relevance (“usages observed as public law,” art. 1 of the Civil Code).
According to prevailing opinion, custom has value, if and insofar as it is admitted by legislative law, at least in modern legal systems. This does not mean that one should a priori and entirely deny the admissibility of “innovative or introductory” customs (admission is generally accepted for “interpretative or executive” ones), at least in matters not regulated by positive law. “Abolitive” (or “desuetude”) and “modifying” customs of laws seem instead to be excluded outright by Article 15 of the Preliminary Provisions (“Laws are abrogated only by subsequent laws...”), though it cannot be ruled out that this general principle may be derogated by some particular provision that, explicitly or implicitly, admits abrogation or modification in given cases.
It must be considered that the principles indicated also apply after the entry into force of the new Constitution, although no reference to customs is found therein, and previous customs have no further reason to exist, such as those based on the presupposition of the former monarchical regime. On the other hand, those based on the presupposition of the restored parliamentary regime may revive, although it is sometimes difficult to determine whether they are true customs or mere practice or constitutional correctness, the former based on conforming precedents and the latter on ethical-political considerations, which, as such, could constitute a step toward the formation of customs but are not in themselves binding.
The problem of the insertion of usages into the hierarchical system of sources has been expressly resolved by the Italian legislator in the sense that they come after laws, regulations, and even the so-called “corporative norms” (a terminology proper to the abrogated corporative system, now to be understood as “collective labor agreements” or even “economic agreements” between categories of production, insofar as they are still admissible; cf. Preliminary Provisions, art. 1 et seq.). Various provisions in specific matters are reserved; thus, in maritime, inland, and air navigation (as already in commercial matters), usages, while remaining subordinate to the legislative law proper to the matter itself, nevertheless prevail over general civil law (art. 1 of the Navigation Code). Local or special usages prevail over general ones by virtue of the principle of the prevalence, among sources of the same type, of the one containing a special norm over that containing a general norm. Collections of usages are curated by the Chambers of Commerce, Industry, and Agriculture.