The Constitutional Tribunal yesterday ruled by a 12-2 majority that articles 1 and 19 of the EU treaties – respectively establishing the powers of the EU and its courts – are incompatible with Polish law.

The move is the latest salvo in a long-running conflict between the country’s right-wing Law and Order (PiS) government and the EU institutions, which have sounded the alarm over the rule of law in Poland.

In a statement issued yesterday, the European Commission said the ruling “raises serious concerns in relation to the primacy of EU law and the authority of the Court of Justice of the European Union”.

It added: “The Commission upholds and reaffirms the founding principles of the Union’s legal order, namely that EU law has primacy over national law, including constitutional provisions, and all rulings by the European Court of Justice are binding on all member states’ authorities, including national courts.

“We will analyse the ruling of Polish Constitutional Tribunal in detail and we will decide on the next steps. The Commission will not hesitate to make use of its powers under the Treaties to safeguard the uniform application and integrity of Union law.”

Human rights organisation Amnesty International said the ruling represented “another dark day for justice in Poland”, highlighting the EU courts’ role in protecting the independence of the Polish judiciary.

Eve Geddie, Amnesty’s director of the European institutions office, said: “The ruling is part of a wider struggle over independence of the judiciary in Poland. With the move to brazenly sidestep the EU court and the protection it offers, Poland has steered itself on a collision course with the European Union.

“The EU and member states must take urgent legal, political and financial action and make clear that these fundamental principles are not open to negotiation or gamesmanship.”