Poland’s constitutional court ruled on Thursday that some parts of EU law are not compatible with the Polish constitution and declared that the constitution supersedes EU laws, setting off a legal crisis within the EU.

The ruling was adopted by majority vote and found that Article 4(3) of the Treaty on European Union in conjunction with Article 279 of the Treaty on the Functioning of the European Union are inconsistent with Articles 2, 7, 8(1), 90(1) and 4(1) of the Constitution of the Republic of Poland.

The court found that the EU laws ultra vires impose obligations on the Republic of Poland as a member state, by prescribing interim measures to the organizational structure and functioning of Polish courts as well as to the mode of proceedings before those courts. The case began in April when Poland Prime Minister Mateusz Morawiecki filed a request asking the constitutional court to analyze the “collision between the norms of the European law and the national Constitution.”

The European Commission said it reaffirms the primacy of EU law. The statement said the Commission will “analyse the ruling of Polish Constitutional Tribunal in detail and decide on the next steps,” and it “will not hesitate to make use of its powers under the Treaties to safeguard the uniform application and integrity of Union law.”

President of the European Parliament, David Sassoli, stated that “the verdict in Poland cannot remain without consequences. The primacy of EU law must be undisputed. Violating it means challenging one of the founding principles of our Union.”