Poles Demonstrate in Support of EU Membership

People carry flags, as they take part in a rally in support of Poland's membership in the European Union after the country's Constitutional Tribunal ruled on the primacy of the constitution over EU law, undermining a key tenet of European integration, in Warsaw, Poland, on Oct. 10, 2021. Kacper Pempel/Reuters

WARSAW—More than 100,000 Poles demonstrated on Sunday in support of European Union membership after a court ruling that parts of EU law are incompatible with the constitution raised concerns the country could eventually leave the bloc.

Politicians across Europe voiced dismay at the ruling by Poland’s Constitutional Tribunal on Thursday, which they saw as undercutting the legal pillar on which the 27-nation EU stands.