The European Commission President has warned Poland its stance on EU law calls into question the foundation of the bloc and cannot go unpunished.
Ursula von der Leyen's comments follow a recent judicial ruling in Poland which found its national law has primacy over the EU's.
President von der Leyen says the commission's considering fines and triggering a procedure that could strip the country of EU membership.
She says the bloc will not fail to act.
"I am deeply concerned.
"This ruling calls into question the foundations of the European Union.
"It is a direct challenge to the unity of the European legal order."