In Foreningen af Arbejdsledere i Danmark v Daddy's Dance Hall A/S (Daddy's Dance Hall) [1988] IRLR 315 ECJ , the ECJ held that the provisions of the Acquired Rights Directive are mandatory and "therefore independent of the will of the parties" to the employment contract, although post-transfer variations may be agreed that are permitted by national law "in cases other than the transfer of an undertaking".