The tax rate of 30% for acquisitions in tax class II in the version of the Inheritance and Gift Tax Reform Act 2009 is not unconstitutional; see also Federal Finance Court January 20, 2015 (II R 9/11).
Unconstitutionality of tax class II
Context
For acquisitions for which the tax became chargeable after December 31, 2008 and before January 1, 2010, the tax rates in tax class II were similar to those in tax class III.
For more details see Koeniger, The German Inheritance and Gift Tax, 2017, p. 261 et seqq.