Poland was sued on Wednesday in the EU’s highest court for violating EU law through the Polish Constitutional Tribunal’s case law, according to a statement from the European Commission.

The action is a part of a larger dispute over the rule of law between the European Union and Poland’s euroskeptic and nationalist government, which has been going on since 2015 and has already led to the suspension of EU funding for Warsaw.

The Commission’s move on Wednesday was triggered by rulings by the Polish Constitutional Tribunal from July and October 2021 that provisions of EU Treaties were incompatible with the Polish constitution, expressly challenging the primacy of EU law over national law.

“The Constitutional Tribunal with these rulings breached the general principles of autonomy, primacy, effectiveness, uniform application of Union law and the binding effect of rulings of the Court of Justice of the EU,” the Commission said.

“The Commission’s objective is to ensure that the rights of Polish citizens are protected and that they can enjoy the benefits of the EU in the same way as all EU citizens. Primacy of EU law ensures equal application of EU law across the Union,” the Commission said.

The EU executive arm, which is in charge of making sure all of the EU’s 27 countries apply the bloc’s laws and respect its treaties, also said the Polish tribunal’s rulings breached EU laws that guarantee the right to effective judicial protection by giving it an unduly restrictive interpretation.

“Thereby it deprives individuals before Polish courts from the full guarantees set out in that provision,” it said.

The Constitutional Tribunal is charged with checking if laws passed by parliament and signed by the president into law are compatible with the Polish constitution.

The Commission said that after changes made to the tribunal by the ruling nationalist and eurosceptic party PiS, it no longer met the requirements of an independent and impartial tribunal previously established by law.

“This is due to the irregularities in the appointment procedures of three judges in December 2015 and in the selection of its President in December 2016,” the Commission said.

The EU executive arm sent all its views on the tribunal to the Polish authorities last July, but Warsaw rejected the arguments in September.

“This is why the Commission decided today to refer Poland to the Court of Justice of the European Union,” the Commission said.