Poland’s dispute with the EU over the primacy of EU law is overshadowing a summit of the 27 member states getting under way in Brussels.

The EU may impose sanctions on Poland over a ruling by its highest court that some parts of EU law are incompatible with the Polish constitution.

EU case law rests on the principle that EU law has supremacy over national laws. The Polish government has been accused of politicising the judiciary.

The government alleges EU “blackmail”.

The rule of law dispute is on the summit agenda, but the leaders will also discuss other major issues:

  • the continuing challenges of vaccinating against Covid-19, amid a new surge in infections
  • the spike in energy prices hitting businesses and consumers
  • climate change and the imminent COP 26 summit in Glasgow
  • migration pressures, notably tensions with neighbouring Belarus, whose leader Alexander Lukashenko is accused of trafficking migrants as a way to retaliate for EU sanctions.

On arrival Germany’s Chancellor Angela Merkel said “rule of law is a core aspect of the European Union”. “At the same time, we have to find ways of coming back together, because a cascade of cases at the European Court is not a solution.”

The dispute has sharpened a divide between the ruling nationalists in Poland and neighbouring Hungary and the liberal politicians who are in the majority across the EU. Opinion polls suggest an overwhelming majority of Poles support their country’s EU membership.

Polish Prime Minister Mateusz Morawiecki clashed in the European Parliament on Tuesday with European Commission chief Ursula von der Leyen.

He again accused the Commission on Thursday of overreaching its legal mandate, saying “we will not act under pressure of blackmail.

“We are ready for dialogue. We do not agree with the constantly broadening range of competencies [of the EU] but we will of course talk about it, how to resolve the current dispute with understanding and dialogue.”

Hungary’s nationalist Prime Minister Viktor Orban backed Poland’s case, saying “the fact is very clear: the primacy of EU law is not in the treaty at all, so the EU has primacy where it has competencies… what’s going on here is regularly that European institutions circumvent the rights of the national parliament and government”.

The EU has taken legal action against both Hungary and Poland over rule of law issues, accusing them of defying EU values on judicial independence, media freedom and minority rights, notably those of migrants and gay people.

The European Commission is yet to approve €57bn (£48bn; $66bn) of Covid-19 recovery funds earmarked for Poland, and may not do so until the dispute is settled.

Dutch Prime Minister Mark Rutte took a tough stance on that pot of EU money on Thursday. “The independence of the Polish judiciary is the key issue we have to discuss. It is very difficult to see how a big new fund of money could be made available to Poland when this is not settled,” he said.

An annex to the EU’s Lisbon Treaty makes it clear that EU law takes precedence over national laws and that European Court of Justice (ECJ) rulings have enshrined that principle.

Annex 17, the declaration concerning primacy, accepts that the principle is not actually in the treaty itself, but says “it results from the case-law of the Court of Justice that primacy of EC law is a cornerstone principle of Community law.

“According to the Court, this principle is inherent to the specific nature of the European Community.”