LEGITTIMITÀ. – In general, it is conformity with the nature of things, with right, and with the law.
I. CONCEPT
The term legitimate (from which the abstract noun legitimacy is derived) has a very broad meaning: that which accords with the law, is constituted by the laws, just, true, equitable, appropriate; something more precise and determinate than mere legality, which may remain external and apparent, whereas legitimacy is an intimate quality that clothes and pervades what conforms to law, justice, reason, and established norms: conformity to the universal law of justicewhich imposes, sanctions, coordinates, and regulates relations among human beings.
The term is therefore used with the most varied and complex meanings, in the convergent effort to express or indicate the relationship between an act, fact, measure, and the established law. Thus, the legitimate portion is the share of the inheritance which, by provision of law, belongs to each child or his or her descendants and to the surviving spouse, irrespective of the liberality of the deceased or of any testamentary dispositions made by that person. The legal age is the age upon reaching which the law attaches or recognizes the capacity to perform a particular act or conclude a particular juridical transaction, such as the celebration of marriage, the administration of one’s own property, religious profession, etc. A legitimate agreement or contract is one recognized and protected by law. Punishment imposed and served according to the law, guardianship or curatorship assigned by law to minors, incapacitated persons, and persons under interdiction, a marriage actually celebrated and regulated by law, a procedural action granted by law and exercised according to law, self-defense, etc., are likewise called legitimate. Legitimacy, then, in the general sense, requires that an act, a juridical fact, or an administrative measure derive from the law the power to produce the specific effects that the active subject seeks. In an extended sense, it indicates a person’s or dynasty’s right to reign over an established state.
The three principal aspects of legitimacy are considered in relation to family rights, procedural law, and administrative acts, with regard to which one properly speaks of the judgment or review of legitimacy.
II. L. DI NATALI. — With regard to family rights, l. is the condition of offspring born during marriage (v. PROLE).
III. PROCEDURAL LEGITIMACY
In procedural law, legitimacy or standing is the prerequisite for being able to appear in court (v. LEGITTIMAZIONE AGLI ATTI GIURIDICI).IV. REVIEW OF THE LEGITIMACY OF ADMINISTRATIVE ACTS AND MEASURES
With regard to administrative acts and measures, legitimacy is the condition, opposed to illegitimacy, enjoyed by an administrative act or measure, with the effect of full validity, when it is not affected by lack of competence, misuse of power, or violation of the law.a) In canon law the question is highly complex and has not yet been definitively settled. It is certain, however, that the ordinary judge may not rule on the administrative acts of the Ordinaries of places, whose competence is reserved to the Roman S. Congregations, always in an administrative capacity (cf. can. 1601 and the response of the Pontifical Commission for the Interpretation of the CIC, 22 May 1923). Indeed, no tribunal may judge the suitability or otherwise, or the appropriateness, of an administrative act or measure, nor the necessity in which the public authority may find itself of limiting, in the general interest, the exercise of private individuals’ rights.
b) By virtue of art. 5 of the law of 20 March 1865, no. 2248, annex E, the ordinary judiciary in Italy has only the power to review the legitimacy of administrative acts which, within the limits of its specific competence, are referred to it for examination; that is to say, it may ascertain whether and in what respect the administrative act or measure conforms to the laws, consequently refusing to apply it, in relation to the case submitted to it, if the act appears illegitimate, that is, nonexistent or null. An administrative act or measure is nonexistent when an element necessary for its formal existence is lacking, such as a manifestation of will proceeding from a competent administrative body, the prescribed substantive form, and the like; it is null, instead, because of defects relating to the capacity of the person issuing it—for example, lack of power, incompetence (which could degenerate into abuse or usurpation of power), lack of personal capacity on account of age or psychological or legal conditions, pursuant to specific legal provisions—or also because of defects of form which, although they do not impair the substance of the particular act, nevertheless entail an invalidity resulting,
(from R. Klapheck, Hoge, Der Dom zu Xanten, Berlin 1928)
LEGNO — Detail of the Tree of Jesse in the predella of the altar of the Virgin (15th century) — Xanten, Cathedral.

When the defect of illegitimacy does not arise from violation of a law, or from false interpretations or applications thereof, or from an error of fact, the judicial authority may not review administrative acts and measures. In such cases, moreover, its specific jurisdiction is subject to very precise and definite limitations, e.g., that the illegitimacy of the administrative act or measure has infringed subjective rights; that the judge’s inquiry be confined to the facts and not extend to the merits; that it not concern the administration’s discretionary powers within a given sphere, etc. These limitations do not apply, or may be modified, when review of l. is conducted not by the ordinary magistrate but by the Council of State or by special jurisdictions, whose competence nevertheless always excludes any judgment on the merits insofar as this depends on the exercise of discretionary power.