Poland’s membership of the EU was plunged into uncertainty on Wednesday after its judges defied a European court order to reverse some of its controversial judicial reforms.

Stanisław Piotrowicz, a senior Polish judge, said that interim measures by the EU’s highest court, which ordered Warsaw to suspend the reforms, were “not in line” with the Polish constitution.

The defiant ruling is the first of two verdicts due to be issued this week by Polish judges which appear to question a fundamental requirement of EU membership: that EU law takes precedence over national laws.

The ruling prompted Guy Verhofstadt, a prominent MEP and former chief Brexit coordinator, to warn that Poland’s eurosceptic government was trying to drag the country out of the bloc.

“Against the wishes of the vast majority of Polish people who want an EU future, the populist governing PiS [Law and Justice] party is determined to take Poland out of the EU,” he wrote on Twitter.

“Will anyone act to stop them before it is too late?” he added, and claimed that the rule of law in Poland was breaking down.  

The Polish ruling came after the European Court of Justice [ECJ] issued an interim order for Warsaw to suspend its “disciplinary chamber” of the Supreme Court, which was part of measures to overhaul the Polish legal system.

Under the Polish reforms, which came into effect in February 2020, the disciplinary chamber has powers to strip judges of immunity and cut their salaries. The reforms also prevent judges from referring certain points of law to the ECJ.

Poland’s ruling Law and Justice party, a right-wing populist and eurosceptic movement, has clashed with Brussels for years over the hugely contentious reforms.

Warsaw has argued that the reforms will tackle corruption and root out Communist-era judges, but critics say the true purpose is to undermine the role of EU law and open the door to Poland quitting the EU.

Human rights groups are also concerned that the reforms would undermine the independence of the Polish judiciary as they could allow the government to expel judges on political grounds.

A further confrontation with Brussels could erupt on Thursday, when Poland may issue another ruling which will decide whether EU law has primacy over Polish law.

MEPs reacted with shock to the ruling on Wednesday and raised fears of a looming “Polexit,” or Polish exit, from the EU.

"The refusal to implement rulings of the European Court of Justice in Poland is a clear step towards taking Poland out of the European Union," Jeroen Lenaers, a Dutch MEP said.

"We fear that the Polish government is on the path to Polexit," he added.

“We are in the process of a legal Polexit which is taking place step by step," Poland’s independent human rights ombudsman Adam Bodnar told reporters after the ruling.

Former EU Council chief Donald Tusk, head of the Polish opposition Civic Platform party, accused the government of "leaving the EU".

"Only we Poles can successfully oppose this," he tweeted.

While Poland – which joined the EU in 2004 – is run by a staunchly eurosceptic government, polls have consistently shown strong support for remaining in the bloc.