42As the Civil Service Tribunal correctly pointed out in paragraph 45 of the judgment under appeal (see paragraph 10 above), it is settled case-law that Article 277 TFEU gives expression to the general principle conferring upon any party to proceedings the right to challenge indirectly, for the purpose of obtaining the annulment of an act against which it can bring proceedings, the validity of a previous act of an EU institution which constitutes the legal basis of the contested act, if that party was not entitled to bring a direct action challenging the act which thus affected him without his having been in a position to seek its annulment.