On 9 February 2010, the Federal Constitutional Court ruled that the basic welfare rates known as Hartz IV were incompatible with the constitution. Much of its reasoning concerned how the amounts had been reached. The legislature must set the benefit “nachvollziehbar auf der Grundlage verlässlicher Zahlen und schlüssiger Berechnungsverfahren.” That means in a way others can follow, on the basis of reliable figures and consistent methods of calculation. The rate for children had been set as a fixed reduction from the adult rate. According to the court, it rested on “einer freihändigen Setzung ohne empirische und methodische Fundierung,” a figure set freehand, without an empirical or methodical basis. Estimates made “ins Blaue hinein,” at random, are not a realistic calculation. The legislature had until 31 December 2010 to pass new rules.