In case of emergency
The constitutional complaint originally was only part of a federal law (§§ 90 ff. BVerfGG) and not part of the constitution itself. Yet it was incorporated in the Constitution in 1969, because at the same time the so-called (regulations for the case of emergency and war) was incorporated in the constitution. In case of emergency it is possible to impose restrictions on the citizens in respect to certain basic rights. In order to avoid the possibility of simple changes of the federal law, the remedy was incorporated in the constitution.