Article 873-D Federal Labor Law

The parties may request that third parties who may be affected by the resolution issued in the proceeding be called to trial, provided they justify the need for their summons; for this purpose, they must provide the address of the latter, exhibit the necessary copies of the complaint and, if applicable, of the answer, as well as of the documents exhibited by the parties, with which service must be made on the third party; if they fail to comply with such requirements, their right to request the summons shall be deemed lost.

The third party may appear in the trial until before the preliminary hearing; if it fails to do so, it shall be understood that it has no legal interest in the matter, remaining subject to the outcome of the trial.

The interested third party that appears in the trial shall be a party thereto, and must subject itself to the formalities of the proceeding provided in this chapter.

The summons of an interested third party must be made by the parties in the complaint, answer, counterclaim or answer to the counterclaim, or else when issuing the reply and counter-reply, as the case may be; the Court shall rule on said request summarily and, if it is admitted, shall order that the interested third party be summoned so that within the following fifteen days it makes its statements in writing, to which it must attach the evidence it deems pertinent in accordance with the provisions of article 780 of this Law, with sufficient service copies for the parties.