Article 177 of the Treaty establishes a procedure for direct cooperation between the Court of Justice and the national courts, in the course of which the parties concerned are merely invited to submit observations within the legal framework set out by the court making the reference.

Within the limits established by Article 177 of the Treaty, it is thus for the national courts alone to decide on the principle and purpose of any reference to the Court of Justice and it is also for those courts alone to judge whether they have obtained sufficient guidance from the preliminary ruling delivered in response to their reference or whether it appears to them necessary to refer the matter once more to the Court. Accordingly, the parties to the main proceedings cannot rely on Article 41 of the Statute of the Court of Justice or on Articles 98 to 100 of the Rules of Procedure in order to seek revision of rulings delivered in pursuance of Article 177. Only the national court to which such a ruling is addressed may, if appropriate, submit new considerations to the Court which might lead it to give a different answer to a question submitted earlier.