BRUSSELS - The European Commission will do all in its power to ensure the primacy of EU law, its president Ursula von der Leyen said on Friday, after a ruling by Poland's highest court that had left her "deeply concerned".
The Polish Constitutional Tribunal ruled on Thursday that some parts of EU treaties are incompatible with the Polish constitution, challenging a pillar of the European Union and sharply escalating discord between Brussels and Warsaw.
"EU law has primacy over national law, including constitutional provisions," von der Leyen said in a statement.
"This is what all EU member states have signed up to as members of the European Union. We will use all the powers that we have under the treaties to ensure this."
The EU executive's chief ordered a thorough and swift analysis of the ruling, on the basis of which the Commission would decide its next steps.
The European Union, she said, was a community of values and laws on which 450 million Europeans, including Poles, relied.
"Our utmost priority is to ensure that the rights of Polish citizens are protected and that Polish citizens enjoy the benefits granted by membership of the European Union, just like all citizens of our union," she said.
EU citizens and businesses needed legal certainty that EU rules, including rulings of the European Court of Justice, were fully applied in Poland, she said.
"Our treaties are very clear. All rulings by the European Court of Justice are binding on all member states' authorities, including national courts," she said.