European Commission Vice President Frans Timmermans said the decision to trigger proceedings against Poland that could lead to sanctions had been made “with a heavy heart.” (Virginia Mayo/AP)

The European Union's executive arm triggered unprecedented disciplinary action against member state Poland on Wednesday, after months of tensions over what the E.U. calls a "clear risk of a serious breach of the rule of law" in the country.

But in an indication that Poland remains unwilling to back down, its president soon afterward signed into law sweeping changes to the judicial system that are at the core of the dispute.

The European Commission's decision to initiate a process under the E.U.'s Article 7 does not result in any immediate sanctions, but it could ultimately strip Poland of its E.U. voting rights — a penalty that some describe as the "nuclear option." Such a move, however, would require the unanimous support of other bloc members, and Hungary's E.U.-skeptical government has pledged to block it.

Wednesday's decision highlighted the growing strain between E.U. headquarters in Brussels and Warsaw, where an E.U.-friendly Polish government was replaced by a right-wing one in 2015.

Poland, the birthplace of Eastern Europe's pro-democracy movement in the 1980s, has long been praised as a role model for its transition from communism. A vast majority of Poles still support the E.U., and Poland remains one of the largest beneficiaries of E.U. funds. But the ruling Law and Justice party has been at odds with several of the bloc's recent decisions, which it considers too liberal.

[In Poland, a window on what happens when populists come to power]

The bloc's action Wednesday stemmed from Poland's controversial changes to its justice system. The measures were widely criticized elsewhere in Europe as an affront to the rule of law and a threat to democracy.

Some fear that the E.U. action against Poland could undermine public support for the bloc, playing right into the hands of the government.

But the European Commission's deputy head, Frans Timmermans, said that the dispute centers on issues critical to the future of the E.U. and that the Article 7 decision was made "with a heavy heart."

"This is not just about Poland, it is about the EU as a whole," he wrote on Twitter.

"If you put an end to, or limit, the separation of powers, you break down the rule of law, and that means breaking down the smooth functioning of the union as a whole," Timmermans said.

Poland has three months to address the E.U. concerns, but it has shown little willingness to make concessions. On Wednesday, the government indicated that it considered the E.U. decision unfair, calling it "essentially political, not a legal one.

"It puts an unnecessary burden on our mutual relations, which may render it difficult to build understanding and mutual trust between Warsaw and Brussels," the Polish Foreign Ministry said in a statement. Poland stands ready to defend the legality of its reforms at the Court of Justice of the European Union, it continued.

Poland's ruling party has repeatedly clashed with E.U. officials in recent months, notably over proposed press freedom restrictions and refugee resettlement plans.

Among the changes to the judicial system that were considered was a measure that would allow the government to remove Supreme Court justices and another that would give it effective control over judicial appointments.

In an unexpected move only days after Parliament approved both the measures, President Andrzej Duda rejected them, though he allowed two other changes to proceed — one of which gives the government more control over local courts.

"Poland needs a reform, but a wise one," he said in a statement at the time. "I am aware I will be criticized, probably by both sides of the political scene, but I make my decision with great responsibility for the Polish state."

Duda's endorsement Wednesday of modified versions of the proposals he earlier rejected clears the path for a sweeping overhaul of Poland's justice system.

Read more:

Poland’s long march toward democracy is threatened by quick steps away from it

Poland’s president unexpectedly intervenes to protect independent courts

Poland’s autocratic counterrevolution draws nearer

Today’s coverage from Post correspondents around the world

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