PREVENTION (of jurisdiction)
Prevention (of jurisdiction) is the efficacy attached to the assertion of priority, whereby a judge, by preventing another judge—who is also competent in his own right—from exercising jurisdiction, remains the sole competent authority to adjudicate.
Prevention of jurisdiction can occur in two cases: in so-called causes of mixed forum, where both the State and the Church are competent, and among competing ecclesiastical tribunals.
### I. IN CAUSES OF MIXED FORUM
In addition to causes that belong exclusively to the ecclesiastical forum, there are other causes that can be adjudicated either in the ecclesiastical forum or in the civil forum, and are therefore called causes of mixed forum.
These causes are either inherently temporal but with an inseparable spiritual quality added, or spiritual causes that present some temporal aspect. However, causes that civil authority adjudicates by concession of the Church—through concordat or otherwise—are not of mixed forum; for example, causes concerning the separation of spouses, patronage rights, etc.
Causes of mixed forum can be criminal or contentious, and the latter can belong to the mixed forum either by their nature or by the status of the persons involved. The following causes are of mixed forum by their nature: acts and contracts accompanied by an oath, testaments of laypersons with annexed legacies, the mere existence of a spiritual fact such as marriage or baptism (excluding the question of the validity of the act), etc.
Some of these causes have now been entirely remitted by the Church to the civil forum (e.g., those concerning civil effects attached to marriage, unless they are raised incidentally and accessorily to a question directly concerning marriage: can. 1016, 1961).
By reason of the status of the persons, causes concerning orphans and widows were once considered of mixed forum. Since today the authority of the State, in civilized countries, fully safeguards these rights, they are left to the State. Criminal causes of mixed forum pertain to offenses repressed by both ecclesiastical and civil law (can. 2198). They concern crimes against life, liberty, property, good reputation, and morals, as well as certain crimes against religion, such as violations of corpses, tombs, cemeteries, and direct violations against ecclesiastical persons. In all these contentious and criminal causes of mixed forum, prevention should prevail between ecclesiastical and civil tribunals (can. 1553 § 2). Consequently, if a case is pending before an ecclesiastical tribunal, it cannot be introduced before a civil tribunal, and vice versa. In the ecclesiastical forum, a case is considered pending from the moment of citation (can. 1725, n. 5) and remains so as long as the parties or the judge have the opportunity to perform some procedural act. Once the instance has lapsed or the claim has been extinguished by prescription, the case may be reintroduced before any tribunal.
Moreover, in such matters, judgments rendered by Church tribunals should also be valid before State tribunals, and vice versa. The Church, in fact, considers judgments rendered by lay tribunals as res judicata. Since, however, the State does not always today respect the pending litigation before ecclesiastical tribunals or the judgments rendered by the Church, the Code of Canon Law stipulates that whoever, after introducing a cause before the ecclesiastical forum, submits the same cause to the secular forum shall immediately forfeit the right to proceed in the ecclesiastical forum against the same person in the same cause and in matters connected therewith, and may be liable to penalties under can. 2222, even without prior warning, if scandal is given (can. 1554). The offense is consummated with the legally notified citation (can. 1725, n. 2). With regard to criminal causes, since the State generally does not take ecclesiastical penalties into account, the Church, to avoid double punishment, usually does not proceed against lay delinquents after the civil magistrate has sufficiently provided for the public good (can. 1933 § 3), and in general refrains from imposing punishment if the delinquent has been punished or is expected to be punished by civil authority (can. 2223 § 3, n. 2). In practice, therefore, the Church adheres to its own laws while also taking into account punishments inflicted by the State.
In cases of crimes against the faith and the unity of the Church, given the State’s lack of interest under the current regime of tolerance, the Church provides solely through its own laws.
### II. IN THE JURISDICTIONAL ORGANS OF THE CHURCH
According to canon law, competence is determined on the basis of four fundamental criteria: functional, objective, subjective, and territorial. These criteria overlap and combine, so that despite the delimitation of competence established by law, there can be a multiplicity of forums equally competent in the same cause. When, for various reasons, several judges are equally competent and the plaintiff can choose any of them to summon the defendant, the judge or tribunal before which the plaintiff actually appears and which, after the libellus, first issues a valid citation to the defendant becomes exclusively competent. By this act, the judge either prevents or preempts every other judge and excludes them from the possibility of adjudicating the cause (can. 1568; cf. 2, 10, X, I, 29; 2, II, 5 in Clem.). However, if one of the parties renounces the cause and a new process is later initiated, the first judge is no longer competent, as this constitutes a new litigation.
For prevention to be effective, the citation must be valid according to can. 1711 et seq. Nevertheless, default does not annul the effect of citation with regard to prevention, unless the defendant is able to purge the default in accordance with can. 1851.
Even in criminal causes, it is the citation that determines the right of prevention, so that even while an inquisition is underway (can. 1939 et seq.), the cause can shift from one judge to another by virtue of prevention. By analogy, the criterion of prevention can also apply in the case where the same cause is pending in two distinct processes before the same judge. The purpose for which the legislator established prevention is *ne bis de eadem re sit actio*. This responds to a public interest, to avoid the wasteful expenditure of energy, excessive burden on jurisdictional organs, and above all to prevent multiple judgments—possibly contradictory—on the same controversy, which would bring discredit upon the administration of justice.