§ 2. On Usual Interpretation

170. Usual interpretation is called that which has been received by use and custom. This can be various in various places, although the matter concerns a universal law, as will be evident from the things to be said concerning the law of fast. But doctors commonly assert that laws are to be interpreted according to the custom of the place, even if the words of the law must be taken less properly.

An interpretation of this kind is equivalent to an authentic one, and, if all the conditions are present which are required for constituting a legitimate custom, it produces altogether the same obligation. Hence the axiom: Custom is the best interpreter of laws (cf. n. 261). It is equivalent only to doctrinal interpretation if the custom has not yet been prescribed, or confirmed by the tacit consent of the legislator (I, 109; H. Ap., II, 82).

Note. To usual interpretation is referred JUDICIAL interpretation, or the practice of tribunals, whether civil or ecclesiastical, when this is constant and uniform; for, although the sentence of a judge makes right only between the litigants, nevertheless the uniformity of decisions induces a certain custom, to which the consent of the legislator tacitly gives support (Bouix, de Princip., P. II, sect. 6, c. 1, § 2, 4).