"Poland must immediately suspend the application of the national provisions on the powers of the Disciplinary Chamber of the Supreme Court with regard to disciplinary cases concerning judges,” the European Court of Justice said in a ruling.
It added that Poland “failed to fulfill its obligations under EU law” by adopting a new disciplinary regime for judges.
The Luxembourg-based court’s ruling came after the European Union’s executive in January asked the EU’s top court to suspend the work of the disciplinary chamber within Poland’s Supreme Court.
The European Commission in October decided to refer Poland to the EU's top court over the new disciplinary rules for judges, in what was the latest step in a prolonged dispute over alleged rule-of-law breaches.
The Commission said in April last year that new Polish legal regulations made it possible "to subject ordinary court judges to disciplinary investigations, procedures and ultimately sanctions, on account of the content of their judicial decisions."
The EU's executive also said at the time that the new Polish “disciplinary regime does not guarantee the independence and impartiality of the Disciplinary Chamber of the Supreme Court which reviews decisions taken in disciplinary proceedings against judges.”
'Dysfunction' among judges: justice minister
Poland's governing Law and Justice party, which came to power in late 2015, has insisted that sweeping changes are needed to reform an inefficient and sometimes corrupt judicial system tainted by the communist past.
Polish Justice Minister Zbigniew Ziobro told reporters last spring that the new Polish measures to discipline judges were designed to fight “dysfunction” and "pathological" behaviour in the Polish judiciary and that they were less political than those in neighbouring Germany.
Ziobro also said at the time that the new disciplinary chamber in Poland’s Supreme Court had been established to deal with lapses among judges, including cases of theft.
He added that previous procedures were inadequate to discipline such judges.
A judicial system 'deeply flawed': PM
Polish Prime Minister Mateusz Morawiecki said in 2017 that his country’s judicial system was “deeply flawed” and that his ruling conservatives were elected with a mandate to overhaul it.
Morawiecki argued in January last year that some of the legal changes made by his conservative government have met with criticism abroad because they are not understood in Western Europe.