Section 10: Interpretation of the Law

1. By interpretation is meant an authoritative explanation of a law in accordance with the will of the lawgiver.

An interpretation is authentic if it is given, either directly or indirectly, by the lawgiver himself, and in that case has the same binding force as the law which it interprets.

Customary interpretation is that which a law receives from the legitimate practice of those who are subject to it. According to an ancient adage, "Custom is the best interpreter of law."¹

¹ "Consuetudo est optima legum interpres." (Codex Juris Can., can. 29).

Doctrinal interpretation is that developed by experts according to recognized rules from the wording and object (ratio) of a law. The rules of doctrinal interpretation may be summarized as follows: a) The presumption is always in favor of the letter of the law. When the text is ambiguous, the words must be taken in their proper, ordinary, and natural meaning. b) If the object and purpose of a law (ratio legis) are obvious, but the phraseology is indistinct, the mind of the legislator and the circumstances of the case must be attended to. c) Laws which confer a favor or privilege may receive a wide interpretation (favores ampliandi), provided there be no danger of injuring a third party and no conflict with the general law. d) Penal laws, and laws which impose a new burden or restriction may be interpreted narrowly, that is, not extending the burden to such as are not strictly included in their terms (odiosa sunt restringenda).²

² Regulae Iuris in Sexto Decret. Bonif. VIII, No. 15: "Odia restringi et favores convenit ampliari." Cfr. No. 49: "In poenis benignior est interpretatio facienda." Cfr. Codex Iuris Can., can. 19.

2. When must a law be observed? The general rule is that a legal obligation should be fulfilled as soon as possible.

When a fixed term is appointed for the fulfilment of a law, this must be observed. In appointing a fixed term the lawmaker may have intended to make the obligation binding only for that period (tempus appositum ad finiendam obligationem). Thus, if one has missed Mass on Sunday, he is not bound to make up for it on some other day. Or the intention may have been merely to impress the urgency of the precept (tempus appositum ad urgendam vel sollicitandam obligationem). In the latter case the obligation must be fulfilled even after the appointed term has expired. Thus, if a man has neglected to make his Easter Communion during the prescribed season, the duty of making it later continues. ³ If in such a case a person knows beforehand that he will be unable to comply with an obligation at or after the time prescribed, he is bound, if possible, to fulfil it earlier.

³ Conc. Trident., Sess. XIII, 9: "... singulis annis, saltem in Paschate."

READINGS.—Codex Iuris Can., can. 17 sqq. (with the commentaries by Aug. Bachofen, O.S.B., Vol. I, St. Louis 1918, and J. Kinane in the Irish Ecclesiastical Record, Fifth Series, Vol. XI, No. 601, pp. 25 sqq.). —Th. Slater, S.J., A Manual of Moral Theology, Vol. I, pp. 100 sqq. —A. Sweens, Theol. Mor., Fundamentalis, 2nd ed., pp. 198 sqq. —A. Tanquerey, S.S., Synopsis Theologiae Moralis, Vol. II, pp. 166 sqq. —A. Vermeersch, S.J., Theol. Mor., Vol. I, Bruges 1922, pp. 159 sqq.