INTERVENTION IN THE CAUSE. — This is the entry into the procedural relationship of a third party who was extraneous to it at the moment when it arose (can. 182).
Intervention in the cause is of various kinds. In the first place, it is either voluntary or compulsory (can. 1833), according to whether it is effected by the spontaneous initiative of the third party or at the request of one of the parties or by order of the judge. Voluntary intervention in the cause is, in turn, distinguished into principal, accessory, and joinder, according to whether it is made to exclude a competitor’s instruction, or to assist, or on the simple presupposition of the fear that the judgment may prejudice the intervener in the same way as it would prejudice the party to which the intervener, by virtue of the joinder, would become bound.
In particular, principal intervention in the cause, as well as accessory adhesion, presupposes the following conditions: that there be a third party; that there be a pending process in which the third party intends to intervene; that there be the genuine intention of the third party to intervene; and, finally, that there be, in the judge before whom the judgment is already pending, competence to know of the claim of the intervener. It should be noted that, with regard to the element of interest, it suffices that this be juridical, deriving, that is, from the incompatibility, due to identity of the object of the claim and of the cause of action, between the right that the third party asserts by intervention in the cause and that asserted in the cause by the parties. Since in this case intervention in the cause is voluntary, it is evident that the rights of the third party remain unimpaired if the intervention is not effected.
In accessory or simple adhesion intervention in the cause, the third party has a non-autonomous but reflexive legitimation. That is to say, it is in function of the judgment already existing between the parties, or rather of the defense that one or some of these have proposed, so that the third party, in a separate process, would not be legitimated to proceed against the opposing party of that one in whose aid it proposes its intervention.
In autonomous or joinder adhesion intervention in the cause, finally, the third party intervenes to assert a right deriving from the object of the claim or from the cause of action already asserted in the judgment; but, unlike principal intervention in the cause, it does not propose two distinct claims against the two parties to the process, but a single claim against one of them; and, unlike accessory intervention in the cause, it has an autonomous legitimation that allows it to assert its right even in a separate process.
In the two forms of compulsory intervention in the cause (at the instance of a party or by order of the judge), the initial procedural conduct of the third party is characteristically passive. In compulsory intervention in the cause at the instance of a party, as a rule, the interest of each of the parties in the cause in the integration of the judgment with regard to the third party derives either from the fact that it considers the cause common to the third party, by reason of identity or connection of objective elements, or from the fact that the third party has assumed the obligation to guarantee to the interested party the right asserted in the suit. Compulsory intervention in the cause by order of the judge, on the other hand, has no other condition than the judge’s discretionary evaluation of the process, so that it may seem opportune to him, for the sake of procedural economy and in order to eliminate the danger of contradictory judgments, once the pending cause is considered common to the third party for any reason, to order the citation of the latter. This form of compulsory intervention in the cause usually recurs in causes of public interest and, according to the majority of authors, has merely instructional purposes; it can also be effected at the appellate stage.
INTERVENTION, PRINCIPLE OF NON-. — In international law, the juridical figure of intervention arises when one State interferes in the internal affairs of another in order to obtain a particular conduct from II.
Intervention is lawful, and therefore legitimate, when it does not infringe that freedom of action which international law recognizes in every State; it is illicit in the opposite case. In practice, intervention is considered an instrument both for the protection of subjective rights and for that of mere international interests.
In the first case, and on this point doctrine is unanimous, intervention is lawful when it is justified by a particular conventional norm. Particular interest attaches in this connection to those treaties that establish a control or an economic-financial regime among States, very numerous at present or in prospect in recent times and in which an attempt is also made to find a common basis on which to construct an international community, or for the moment merely a European one. Besides particular treaties, intervention can be contemplated by treaties of a general nature: typical among these was the Covenant of the League of Nations, officially dissolved on 18 Apr. 1946 following the creation of the Statute, or Charter, of the United Nations, signed by fifty States on 26 June 1945 and entering into force on 24 Oct. of the same year.
Moreover, intervention can be determined by a general international norm. Thus doctrine examines whether the infringement of another’s right can become lawful or not prohibited when it is connected with self-help, legitimate defense, and state of necessity. The lawfulness of intervention is generally recognized when it is the consequence of a violation of a subjective right of the intervening State committed by the State against which the intervention is directed. The same can be said for intervention caused by legitimate defense, that is, in cases in which one wishes to protect the territory, citizens, or goods of the intervening State. It is controversial whether intervention can be legitimated by state of necessity, since the appraisal of the gravity of the threat affecting the intervening State is made by the State itself and hence in it there may lurk more a political exigency than a juridical justification.
In the second case, that is, when intervention is directed not to the defense of subjective rights but of mere international interests, the real problem of its admissibility or lawfulness arises, in view of the numerous actions of States that exert pressure on the conduct of another State to force it to adopt a stance conforming to their interests without any juridical title.
Two contrasting theories contend for acceptance.
One, called the general theory of intervention, considers this as a lawful means for the protection of international interests, even without a juridical title admitting II. To this theory it can be objected that it has not yet been possible to demonstrate the existence even of a single interest for whose protection a State is authorized by international law to infringe another’s right. An act of this kind would not only be opposed to the fundamental right to freedom, but would also violate justice and the international order, which have their foundation, or rather their juridicity, in the universal natural law.
The other theory, known as the general theory of non-intervention, was condemned by Pius IX (in the allocution *Noces et ante* of 28 September 1860, the Syllabus, proposition LXII), on the grounds that, in deference to the sphere of freedom left to each State by international law, any intervention that is not founded upon a legal title (whether a general norm of international law or a specific conventional norm) denies the possibility of juridically constructing intervention as a means of protecting interests not recognized by international law. Still adhering to the uncertain positivist spirit that informs the present international legal order, intervention could not even be justified on humanitarian grounds, in cases where fundamental human rights are violated. To this erroneous principle of non-intervention, it may be objected that when a grave and reasonable cause exists—which must certainly not be reduced to the defense of a mere interest—it is lawful, and in some cases even obligatory, to intervene in the internal and external affairs of other States.
The means by which intervention may be effected are manifold, but in general it must be borne in mind that the acts by which it is carried out must always conform to customary or particular international law.
Intervention, which properly consists in the use of coercive measures or the threat thereof, must be distinguished, for example, from the offer of mediation, protests made by diplomatic notes, the severance of diplomatic relations, and so forth; finally, intervention cannot and should not be identified with war, which is a distinct institution, whether in regard to the causes that may determine it, the manner in which it must be conducted, or its effects.
Historically, a first enunciation of the principle of non-intervention is found in the Peace of Westphalia, signed on 24 October 1648, albeit limited to conflicts of religion. The principle was applied in the proper political sphere when, toward the end of the 18th century, the France born of the Revolution sought to resist the intervention of the European Powers aimed at restoring the French monarchy; it was studied in particular during the first half of the 19th century, when the members of the Holy Alliance sanctioned its lawfulness in cases where revolutionary movements in other States threatened legitimist principles.
The attempt at intervention in favor of Spain against the revolutionary movements of the South American colonies provoked the message of 2 December 1823 by President Monroe, which gave rise to the doctrine of non-intervention by European Powers in American affairs, while reserving to the United States of America the right to intervene in the affairs of other American States. In the second half of the 19th century, interventions occurred particularly against religious oppression and the oppression of ethnic minorities. In the period closest to our own, intervention has tended to change in form: from armed intervention it has generally become diplomatic, only to revert to armed intervention during the First World War (1914–18). In more recent times, from the outset of the Second World War, a distinctly interventionist program has been evident, which, after the end of the war, has assumed various characteristics (economic aid, political-military aid, etc.).
Nevertheless, the general principle of non-intervention is once again enunciated in Article 2, paragraph 7 of the United Nations Charter (1945): “Nothing contained in the present Charter shall authorize the United Nations to intervene in matters which are essentially within the domestic jurisdiction of any State.” This principle has received fresh contradiction from events now unfolding in Korea.