Eurocrats sent a formal notice to Germany for “violation of fundamental principles of EU law”.
Berlin has two months to respond, and could be dragged in front of EU judges in Luxembourg if its response is unsatisfactory.
German MEP Gunnar Beck, legal affairs spokesman for the AfD’s EU Parliament delegation, said his country’s constitutional court had ruled correctly against the ECB’s stimulus programme.
He insisted that the EU is attempting to force the independent Karlsruhe court to “subordinate itself to the ECJ”.
“Which equates to a loss of sovereignty for Germany,” he added.
Mr Beck declared that the Federal Constitutional Court is there to “protect the citizen from violating contractual attacks of the EU”.
“This protection is not only permissible, but also mandatory.
“By the way, the relationship between the EU and national law is similar to that of many other national constitutional courts, among others in Denmark, Hungary or Poland.
“The EU is not sovereign, but the member states.”
Asked whether Germany had set a poor example, Steffen Seibert added: “I certainly wouldn’t want to play it down in any way but we’re not the only ones.”
The row emerged after last May German judges ruled that the ECJ had breached its mandate with an “incomprehensible” ruling justifying ECB bond purchases.
In response, the Commission said Germany’s decision to say the ECJ had gone beyond its powers had “deprived a judgement of the European Court of Justice of its legal effect in Germany, breaching the principle of the primacy of EU law”.