LIBELLUS. - It is the written act of a party by which the subject matter of the suit that is to be brought is proposed to the competent judge. The origin of the L., as a means of introducing a process, is very ancient.
From the 5th century the written form was in constant use for the introduction of cases, even before the imperial tribunals.
This custom was later codified, so much so that in the Decretals of Gregory IX there is a special title De libelli oblatione (t. III, l. II). It may be said that the presentation of the L. was essential for the purposes of the subsequent conduct of a case, so much so that no judgment existed without an L. An exception to the rule were summary cases, for which the claim could be made orally, though it was subsequently drawn up in writing by the notary (c. II, V, 11 in Clem.). The CIC, in title VI, chap. I, book IV, De libello litis introductorio, does no more than confirm the usage established in the law of the Decretals, admitting only two exceptions to the written statement of the claim; the first is the case of one who does not know how to write, the second takes up the usage, mentioned above, of being able to make the claim orally in cases of lesser importance and of easier solution and investigation. Even in these cases, however, the notary must draw up a written act which, confirmed and signed by the party, takes the place of the L.
That the L. is absolutely necessary is stated by the CIC itself in can. 1706: "If a person wishes to summon another person before a court, he must present to the competent judge an L. in which the subject matter of the controversy is stated and the ministry of the judge is requested."
In can. 1708 it is indicated what the content of the L. must be. Two celebrated verses, to be cited by way of curiosity, express what the L. must set forth: "Quis, quid, coram quo, quo iure petatur et a quo - recte compositus quisque libellus habet." The L. must therefore indicate the judge, that is, the tribunal competent to hear and decide the controversy; the subject matter of the controversy itself, whether immediate, e.g., condemnation, declaration of a right, or mediate; the persons, whether natural or moral, since all uncertainty must always be removed as to the identity of the one who asks and of the one from whom something is asked; the right on which the claim is founded. Moreover, an essential requirement is the signature of the plaintiff or of his procurator. This as regards the substantive content of the L.; as regards the form, the requirements are brevity and clarity of exposition, all the more so since the precise determination of the elements of the process is carried out in the joinder of issue.
The canonical procedural system grants the party only the power to draw up and present the L.; the citation of its content is already an act of the judge and follows the examination of the L. itself. In fact the judge, having received the L., must carry out an examination of his competence and of the plaintiff's legitimacy to stand in judgment, and must further carry out an examination of the content of the L. both from the substantive and from the formal side. This examination, which must be carried out within one month of presentation, ends with the issuance of a decree by which the L. is admitted or rejected. In the first case the judge will summon plaintiff and defendant for the joinder of issue. More complex and more worthy of consideration is the case of rejection of the L. In fact the tribunal and its president reject it either for emendable errors, in which case the party may either present a new one to the same judicial office or have recourse to the judge immediately superior, or for any other cause, and then, the rejection of the L. being equivalent to the denial of a ruling on the merits, there remains to the party only recourse to the judge immediately superior, a recourse which, although it has an analogy with appeal, nevertheless differs from it, because the examination is not preceded by a proceeding, as indeed also happens before the tribunal first approached, and because it does not end with a sentence, but with a decree from which no appeal lies. If the appellate tribunal decides in favor of admission, the lower judge, to whom the decision on the merits is referred under the rules on competence, must proceed to the citation and to the further acts. If instead the appellate tribunal decides that the L. must be rejected, this decision is final, without prejudice always to the party's right to bring a new claim by a new L.
Also in the Code of Civil Procedure of the State of Vatican City, albeit under the name of judicial claim, a name which some authors would have preferred also for the CIC, the introduction of the suit is done by means of an L.; here too the citation is already an act of the judge, who however cannot reject the L., but only invite the plaintiff to complete or correct it.