BRUSSELS (Reuters) - The European Commission opened a fresh legal case on Monday against Poland over changes to the Supreme Court that it fears will further undermine judicial independence in the largest ex-communist member of the bloc.
The European Union's executive arm gave Poland a month to respond, which means the legal procedure will not stop the law entering into force on Tuesday.
"The Commission is of the opinion that these measures undermine the principle of judicial independence, including the irremovability of judges," it said in a statement.
The Commission has challenged several changes to the judiciary that Poland's nationalist Law and Justice (PiS) party has made since winning power in late 2015.
The EU body says the policies weaken democratic checks and balances. The Polish government says they are needed to reform a system which dates back to communist times.
The EU has opened a broader investigation into the rule of law in Poland which could, in theory, lead to sanctions. But that is unlikely to happen as any such actions would be vetoed by Poland's eurosceptic ally, Hungary.
But the latest legal move highlights Poland's growing isolation in the EU under the PiS and weakens its hand as the bloc is negotiating its next seven-year budget from 2021.
(Reporting by Gabriela Baczynska; Editing by Robin Pomeroy)