The decisions of the FCC on the constitutionality of laws are binding upon all public authorities (s. 31(1) – Act on the FCC ) and generally have the force of laws (first and second sentences of s. 31(2) ).
If the FCC determines that a law violates the Basic Law, this leads to the ex tunc and intra et erga omnes nullity of the law (78(1), 82(1) and 95(3)) and therefore to an absolute prohibition on applying the law in question. As a consequence, in principle, all legal acts which were adopted on the basis of the said law (e.g. judgments, administrative regulations and individual administrative decisions) are deprived of their legal basis (s. 79 Act on the FCC).
(Temporal effects of Decisions of the German Federal Constitutional Court în The Effect of Judicial Decisions in Time, Intersentia, 2014, la p. 22)