The Constitutional Tribunal is the highest judicial body in Poland, responsible for checking the compatibility of laws and international agreements with the country's constitution.
The European Union's top court ruled on Thursday that Poland's Constitutional Tribunal was not "independent and impartial" because of politicised appointments made under the previous conservative government.
In its ruling, the EU's Court of Justice said the Polish Constitutional Tribunal had "infringed the principle of effective judicial protection" and "disregarded the primacy, autonomy, effectiveness and uniform application of EU law."
The Constitutional Tribunal is the highest judicial body in Poland, responsible for checking the compatibility of laws, policies and international agreements with the country's constitution.
Between 2015 and 2023, Poland's former ruling Law and Justic party drastically transformed the justice system, including establishing political control over top courts such as the Constitutional Tribunal and the Supreme Court.
That put Poland on a collision course with the European Commission, the EU executive, which challenged some of the reforms in front of the EU top court and suspended payments of funds to Poland.
The EU court said the way three of the judges and the president of the Polish Constitutional Tribunal were appointed under the Law and Justice party called into question its status "as an independent and impartial tribunal established by law within the meaning of EU law."
In theory, such a ruling by the top EU court should trigger national reforms to restore the independence of the Polish Constitutional Tribunal, a requirement for the country to be in the EU.
In practice, two successive ministers of justice appointed by a new liberal government, in power since 2023, have failed to restore the independence of that court.
The main reason is that Poland's current and former presidents, both politically aligned with Law and Justice, have either vetoed or promised to veto legislative changes that would reverse the reforms.
Poland's Justice Minister Waldemar Żurek welcomed Thursday's ruling.
"This ruling obliges our state to take action," he said in a comment posted on X. "We must rebuild a genuine, independent Tribunal together. This is a fundamental issue for the state and citizens. We are ready for this task."