165On the date when this action was brought, the illegality of Article 28(6) of the SatCen Staff Regulations had not been established by the General Court. Accordingly, the referral to the Appeals Board, adjudicating in accordance with powers conferred on it by that provision, was founded on a legal basis and constituted a legal remedy offering the applicant, in principle, a means of remedying her situation, since it could not be ruled out a priori that the Appeals Board would annul the contested decisions of the Director of SatCen. According to settled case-law, measures of the EU institutions are in principle presumed to be lawful and accordingly produce legal effects until such time as they are withdrawn, annulled in an action for annulment or declared invalid following a reference for a preliminary ruling or a plea of illegality (see judgment of 6 October 2015, Schrems, C‑362/14, EU:C:2015:650, paragraph 52 and the case-law cited).