WARSAW — Poland’s newly elected government brushed aside opposition complaints, large street demonstrations and rising international concern to push through legislation this week that could hobble the country’s highest constitutional court.

It's a battle which is turning Poland from the poster child of post-communist success — a nation whose former prime minister Donald Tusk last year became president of the European Council — into a growing problem for the European Union. Warsaw's perceived trampling of democratic norms is creating alarm in Brussels.

Frans Timmermans, the European Commission's vice president in charge of rule of law and fundamental rights, fired off a letter to Poland's justice and foreign ministers Wednesday, warning the government to slow its push to upend the court.

He was reacting to a law passed by the lower house of parliament Tuesday and approved early Thursday by the senate. It dramatically reshapes the functioning of the Constitutional Tribunal, a 15-judge court that rules on the constitutionality of laws passed by parliament. After the change, rulings will require a two-thirds majority, not a simple majority, and the court will be unable to hold hearings with smaller numbers of judges, slowing its work.

The Law and Justice party (PiS), which took control of Poland’s presidency in May and then won an outright majority in parliament in October, argues the changes are needed to make the court more effective and to better balance it politically. Critics accuse the party of destroying the checks and balances of Poland’s democracy to ram through a radical political program that may not pass constitutional muster.

Jarosław Kaczyński, PiS’s founder and leader and Poland’s most powerful politician who chose both President Andrzej Duda and Prime Minister Beata Szydło for their posts, recently called the tribunal “the bastion of everything in Poland that is bad.”

“All our actions could be questioned for whatever reason,” he said in a television interview.

That was Kaczyński’s experience from 2005-2007, when his party briefly held power and he led a coalition government, which was stymied by the tribunal.

One-party government

Because Law and Justice now controls an absolute majority in parliament — something that hasn’t happened since the end of communism in 1989 — the opposition has been unable to slow its legislative juggernaut. Efforts to derail the bill or at least water it down in committee were easily overridden by Law and Justice.

“That’s the taste of life in the opposition. Yum, yum, yum,” taunted Krystyna Pawłowicz, one of PiS’s fiercest MPs.

With the opposition powerless, PiS’s effort to tighten its grip on the country’s most important institutions is creating a domestic protest movement and growing international disquiet.

“The good of the nation is above the law." — Kornel Morawiecki, interim speaker of parliament.

Demonstrators have staged two mass protests so far in support of the tribunal, and there has also been one large pro-government rally in central Warsaw.

“This is a violation of democracy,” said Jan Niemojewski, who held a big placard with the letter “E” in a lineup of people each holding a letter of the word “DEMOCRACY” during a protest last weekend. “They have the right to rule because they won the election, but they way they’re doing it is really dangerous.”

International concern

There is also growing worry in the EU and among other European countries about the radical change of tone in what had until recently been a country seen as a European success story with growing influence in Brussels.

On Wednesday, Jean Asselborn, the foreign minister of Luxembourg, which holds the EU presidency, called on the European Commission and Parliament to act, saying that sanctions may have to be imposed on Poland if it fails to change course.

“The limitation of the rights of the constitutional court is not acceptable,” he told Reuters.

Timmermans is also worried about Warsaw's direction.

“I would expect that this law is not finally adopted or at least not put into force until all questions regarding the impact of this law on the independence and the functioning of the Constitutional Tribunal have been fully and properly assessed,” Timmermans wrote in his letter.

“We’re a sovereign country which decides on its own about its constitutional bodies,” responded Zbigniew Ziobro, the justice minister. “I don’t think that an external body can impose something on us, because that could conflict with our sense of national pride.”

The battle over judges

A key issue for Timmermans is the fight over naming new judges to the tribunal — a battle that sparked the current crisis.

Civic Platform elected five new judges for the tribunal in early October, when opinion polls showed the party was likely to lose the October 25 elections. Parliament named three replacements for judges whose nine-year terms had expired, and two more whose terms were almost, but not quite, over.

That was ruled a violation of the constitution by the tribunal in early December, which found that the election of the two extra judges was invalid. But PiS seized on the breach in the law and elected five new judges, who were hurriedly sworn in by Duda. The president has refused to swear in any of the judges elected by the previous parliament.

That means, according to the tribunal, there are three legally elected judges who have not been properly sworn in. The government, meanwhile, is ignoring the tribunal’s ruling and insists that the election of the new judges eclipses that of the old ones, and demands that its judges be seated.

The EU’s ability to intervene is very limited. The bloc embarrassed itself in 2000 when it tried to diplomatically isolate Austria, after far-right politician Jörg Haider’s party joined the ruling coalition. The EU treaties now have a provision allowing the European Council to suspend some of the rights of membership of countries found to be in "a serious and persistent breach of fundamental rights." However, that article has never been invoked.

Poland’s new government has also shown that it isn’t especially perturbed by external criticism.

When the German press lambasted Poland’s new rulers, Kaczyński fired back that Poland didn’t need any lessons in democracy from Germany. “Germans owe us a lot in every area, from the moral to the economic. The balance of harm is enormous.”

The fight over the tribunal is only one part of a broader thrust by Law and Justice to take control of most of the country’s institutions. It is purging senior management at state-controlled companies, military officers and civil servants, and the government wants to get a firmer grip on the country’s public media.

A poisoned legacy

While Poland is seen by many as a country that has enjoyed decades of fast economic growth and a rising place in Europe thanks to its membership in NATO and the EU, Kaczyński and his party’s narrative is that modern Poland was flawed from its birth in 1989 — the creation of a corrupt deal between the elites of the Solidarity labor union and the old communist authorities. That means the country needs a revolutionary reconstruction, not a moderate tweak of its institutions.

It’s a program that finds powerful resonance with the young and poorer people, who feel left behind by Poland’s rapid modernization.

“Shame, nothing but shame,” Duda said at a recent ceremony when describing the Polish Third Republic, which came into existence after 1989.

PiS feels its democratic mandate means that drive to reshape the country shouldn’t be undermined by fusty institutions.

“The good of the nation is above the law. If the law conflicts with that good, then we’re not allowed to treat it as something that we can’t break,” said Kornel Morawiecki, a hero of the Solidarity movement who is now an MP for the populist Kukiz movement, which votes together with PiS on many issues.

His speech, made a month ago in parliament, was greeted with a standing ovation from both his party, Law and Justice MPs and Kaczyński.