In his expert opinion commissioned by the Green parliamentary group in the state parliament, Siekmann writes that the across-the-board cuts in global underspending would violate legal principles such as transparency and the budgetary sovereignty of parliament.
Siekmann's expert opinion is available as IMFS Working Paper 173 (PDF).
MDR.de: Thüringer Landeshaushalt: Gutachter hält globale Minderausgabe in Teilen für verfassungswidrig