Government-led constitutional changes in Hungary's judiciary have attracted widespread criticism from home and abroad. Dow Jones's Veronika Gulyas reports on the reaction as well as on the consequent fall in the Hungarian forint. Photo: Getty Images

BUDAPEST—Hungarian lawmakers on Monday passed amendments to the country's constitution, despite warnings from the European Union and the U.S. that the measures could threaten the rule of law and weaken democratic checks and balances.

Parliament, controlled by Prime Minister Viktor Orban's right-leaning Fidesz alliance, approved the changes—including provisions that allow the court system's top administrator and prosecutors to choose which judges hear legal cases—in a party-line vote.

The moves and flaring political tensions with Brussels and Washington combined with investor worries about the autonomy of the country's central bank—where a close ally of Mr. Orban took the helm last week—to help send the Hungarian currency to its weakest level since early June.

After the vote, the EU and the Council of Europe, the Continent's human-rights watchdog, issued a joint statement saying the changes "raise concerns with respect to the principle of rule of law, EU law and Council of Europe standards."

Hungarian legislative leaders and Mr. Orban said that concerns about democratic backsliding in Hungary are unfounded and that their actions are in accord with EU treaties and norms.

The EU, a club of Western liberal democracies, has struggled recently to keep some of the bloc's newer members on what it considers the proper legal path. Brussels, for instance, levied political pressure last summer when rivals of Romania's president changed laws to try to oust him.

Since Mr. Orban swept to power after a landslide electoral victory in 2010, Hungary and the EU have clashed over a broad range of issues, from media freedom to central-bank independence, with Brussels filing several cases against Hungary at the European Court of Justice.

Last week, the Council of Europe called for a delay in voting on the new amendments until they are reviewed by an international commission. EU and U.S. officials also urged more deliberation, saying the proposals raise rule-of-law concerns.

Just before Monday's parliamentary vote, German Foreign Minister Guido Westerwelle told reporters in Brussels that he was "concerned about these latest developments in Hungary," adding that Hungary must understand that the EU is a "community of values."

Critics' main focus has been on changes they say undermine the country's judiciary, such as one barring the Constitutional Court from considering the legality of constitutional amendments and from applying case law and legal precedents predating the new Basic Law, which took effect in 2012.

Mr. Orban's relations with the country's judiciary have at times been contentious. On Monday, he lashed out at a court ruling against state-imposed cuts to natural-gas companies' prices, calling it "scandalous," and saying the government would ask Parliament to approve even bigger reductions.

Civil-rights groups have also complained about amendments that define "family" as a married man and woman and their children, outlaw some kinds of political advertising, and allow the government to prohibit homeless people from living on city streets.

Some opponents of the changes staged a protest at Fidesz party headquarters last week. On Monday, counterterrorism police closed off an area outside the president's office that was to be the site of another demonstration.

After the forint's sudden drop Monday morning, the new economy minister, Mihaly Varga, said the government doesn't want a weaker currency and is ready to intervene to strengthen it.

Mr. Varga was appointed after his predecessor, Gyorgy Matolcsy, left the ministry to run the central bank. He pledged to work to boost investor confidence and revive growth in the recession-hit economy.

"You have to listen to the players in the economy with a receptive ear," he said.

—Veronika Gulyas and Laurence Norman contributed to this article.

Write to Margit Feher at and Gordon Fairclough at