The European Commission decided Wednesday to put Poland on a path that could ultimately lead to the suspension of its EU voting rights over concerns about the rule of law.

The Commission's move was the first time it had ever triggered the so-called Article 7 process, designed to ensure member countries stick to the bloc's core values.

The chances of Poland actually being disenfranchised are slim, as all other EU member countries would need to agree and Hungary, for one, has already said it would veto such a step. But Brussels' decision underscores the depth of concern in the European political mainstream about an overhaul of the legal system by Poland's ruling nationalist-conservative PiS party. Critics say the revamp severely undermines judicial independence.

Commission Vice President Frans Timmermans said the EU's executive had acted "with a heavy heart."

"But the facts leave us no choice," he said.

In response to the Commission's decision, Polish Prime Minister Mateusz Morawiecki defended the government's legal reforms, saying they were "deeply needed."

"Poland is as devoted to the rule of law as the rest of the EU," he said on Twitter. "The dialogue between the Commission and Warsaw needs to be both open and honest. I believe that Poland’s sovereignty and the idea of United Europe can be reconciled."

Other Polish officials struck a more defiant tone.

“The only change this decision makes is that now we must effectively finalize what we have begun — all the way to the very end," said Justice Minister Zbigniew Ziobro. "This is in order for Poland to be respected and this will be guaranteed to us by the rule of law.”

In the latest move to overhaul the legal system, Polish President Andrzej Duda is expected in the coming days to sign into law new measures passed by parliament that would permit the dismissal of many of the country’s Supreme Court judges by lowering their statutory retirement age. Duda confirmed on Wednesday evening that he would go ahead and sign the laws despite Brussels' move.

Timmermans said various reforms undertaken by PiS effectively removed the separation of powers between the executive and the judiciary.

"We do not dispute the right of a government, a nation, to reform its judiciary," Timmermans told reporters in Brussels. "But if you reform the judiciary you need to abide by your own constitution and EU law.”

'Situation deteriorated'

Timmermans noted the Commission had been close in July to triggering Article 7, a mechanism in the EU treaties designed to uphold values such as democracy and the rule of law.

“The situation since then has not improved but deteriorated," said Timmermans, who declared that extensive efforts to engage in dialogue with Warsaw had failed to produce results.

"After two years, the Commission can only conclude that there is now a clear risk of a serious breach of the rule of law," he said.

Warsaw has argued its changes are necessary to root out corruption and modernize a legal system that has elements left over from communism.

Timmermans said the Commission was ready to reconsider its decision if the Polish government implemented changes to the rule of law recommended by Brussels in the coming months.

Outlining the formal steps it would take, the Commission said in a statement it would propose that the European Council “find that there is a clear risk of a serious breach of the rule of law” in Poland.

It also issued a fourth recommendation on the rule of law to Warsaw “setting out clearly the steps that the Polish authorities can take to remedy the current situation.” The recommendation includes amending the Supreme Court law and not applying "a lowered retirement age to current judges.”

Finally, the Commission will decide to take a step further in an ongoing infringement procedure — the measure it undertakes when it believes a country is in breach of EU law — by referring Warsaw to the Court of Justice of the European Union.

The Article 7 process is sometimes dubbed the EU's "nuclear option" as it can lead to the most serious democratic sanction the bloc can impose on a member country — the suspension of its right to vote in EU bodies. But Timmermans played down that description. The first step of the process, he said, meant asking the European Council and European Parliament to consider their own views of the situation in Poland.

However, should the other EU institutions agree with the Commission's assessment — and Warsaw and Brussels fail to find a way to resolve their dispute — then the process could move closer to a vote among member countries on whether to suspend Poland's EU voting rights.

In the most immediate sense, the action against Poland is a loud, public rebuke and a warning to Warsaw that patience has run out in Brussels. While the need for unanimity in the Council makes it unlikely Poland would ever face the most severe punishment, the EU has other arrows in its quiver.

Debate is already underway over the shape of the bloc’s next long-term budget plan, and with the U.K.’s departure creating a big hole, officials are already confronting the need for cuts. Budget Commissioner Günther Oettinger has already called for a new system that would impose tougher “conditionality” on countries like Poland, which are net recipients of EU structural funds.

The idea is that countries that do a better job at implementing EU recommendations on structural reforms would benefit from more funding. And while no fiscal policy could be directed solely at Poland, the budget debate is a reminder that Warsaw has been a major beneficiary of EU spending programs and potentially has much to lose.

Michał Broniatowski and David M. Herszenhorn contributed reporting.