By Martin M. Sobczyk in Warsaw and Laurence Norman in Brussels

Poland's president picked a new head of its constitutional court on Wednesday, brushing off the European Union's concerns about judicial independence being undermined.

President Andrzej Duda installed Julia Przylebska as the court's chairwoman, after more than a year of disputes over judicial appointments between the governing Law and Justice party, the opposition and a majority of the court's judges.

The decision came the same day the EU gave Poland two extra months to address concerns about the rule of law in the country, which it first raised in January.

The face-off between the EU and Poland is one of a series of issues impacting the authority of the EU's executive arm, the European Commission, and threatens to blunt its power to ensure member countries adhere to democratic principles.

Ms. Przylebska was picked as a judge for the court by the government late in 2015. As chairwoman, she replaces Andrzej Rzeplinski, whose term ended Monday.

Polish opposition parties view Ms. Przylebska's appointment as a violation of the rules governing the court. The president picked her after the ruling party pushed through new procedures giving the president a greater say in who gets the job. The EU has questioned the legality of the process.

Several of the court's judges refused to participate in the selection of a short-list for the new court chief, from which Mr. Duda picked Ms. Przylebska.

European Commission Vice President Frans Timmermans said Wednesday he was still considering action that could place financial penalties on Poland and the government strippedof voting rights on some EU matters.

"This case for me is not over simply because a new president of the tribunal was appointed," he said. "We have a long list of issues we are still discussing...and we have not had satisfactory answers on these issues."

Mr. Timmermans said he wanted to give the Polish government more time to respond to a new set of recommendations he was sending to Warsaw.

These would deal with older issues like the government's nomination of judges to the court, its refusal to publish the court's rulings and changes to the court's rules to make it harder for the tribunal to block legislation. They would also deal with more recent issues like the new legislation for picking the head of the court.

"Every Polish citizen has a right to know that the judge he sees or she sees is not under instruction by a political party or a government," he said. "There is a serious issue of the independence of the highestcourt of the land."

However the odds of persuading the conservative Polish government, which swept to office last year, to back down appear slim.

For starters, some of Poland's conservative allies in the region, like Hungary, have indicated they wouldn't support penalizing Poland. Penalties would need the backing of EU governments.

Meanwhile, in Poland, some of those who fought the government over the past year appear ready to stand down, which has sparked large public protests.

Stanislaw Biernat, one of the court's top judge, told a media conference on Wednesday that he and the other members of the court recognized Ms. Przylebska as the chairwoman.

Write to Martin M. Sobczyk at martin.sobczyk@wsj.com and Laurence Norman at laurence.norman@wsj.com

(END) Dow Jones Newswires

December 21, 2016 12:17 ET (17:17 GMT)

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