Poland’s top court has ruled that measures imposed by the European court of justice against the country’s controversial judicial reforms are unconstitutional, in a decision that could have far-reaching implications for the bloc’s legal order. Judge Stanislaw Piotrowicz said on Wednesday that Poland’s constitutional court had reached a majority verdict that EU measures regarding the “system, principles and procedures” of Polish courts were “not in line” with the Polish constitution. The ruling came hours after the ECJ again demanded immediate suspension of a newly established body to oversee Polish supreme court judges, with powers to lift their immunity from prosecution or cut their salaries. The confrontation is expected to ratchet up further on Thursday, when the EU court is due to issue another ruling on the disciplinary chamber’s legitimacy and Poland’s constitutional court – widely viewed as unlawful following a series of appointments of PiS loyalists – could announce its decision in a wider, even more consequential case on whether Polish law has primacy over EU law in general. “We are in the process of a legal Polexit which is taking place step by step,” Poland’s independent human rights ombudsman, Adam Bodnar, said after the ruling on Wednesday. The former European Council president Donald Tusk, now head of the opposition Civic Platform party, accused the governing rightwing populist Law and Justice (PiS) party of “leaving the EU”, saying: “Only we Poles can successfully oppose this.” But the Polish justice minister, Zbigniew Ziobro, said the constitutional court’s decision was “against interference, usurpation and legal aggression by organs of the European Union”. The Luxembourg-based ECJ first asked Poland to suspend the disciplinary chamber last year as part of long-running proceedings against Poland, whose far-reaching reforms the EU says are undermining the independence of the judiciary. PiS, however, insists the reforms are necessary to tackle corruption and remove lingering communist-era influences from the courts, making them more effective, and says Brussels is unjustifiably interfering in its internal affairs. “We’ve seen in recent years that EU bodies such as the Commission or the court of justice of the EU acted in violation of the treaties when they decided to interfere in the Polish judicial system,” the deputy justice minister, Sebastian Kaleta, said this week. Some experts have said Poland’s determined challenge to the primacy of EU law could mark a possible first step towards a Polish exit from the EU – despite opinion polls showing that EU membership remains very popular among Poles. However, Laurent Pech, a professor of European law at Middlesex University in London, said a deliberate exit from the bloc itself would be “political suicide”, predicting instead a gradual “Polexit from the EU legal order”. Rulings favouring the primacy of Polish law over EU law should prompt the bloc to “immediately request daily financial sanctions … and suspension of EU funding”, he said on Wednesday.