Unforeseen and shocking political developments in another member state have placed Ireland at the centre of the biggest crisis facing the EU. No, I am not talking about Brexit but the breakdown of the rule of law in Hungary and, particularly Poland.

Ireland’s central role in this comes from a case that has come before the Irish High Court. Artur Celmer is wanted by the Polish authorities for trial on a number of charges including drug trafficking. An EU law called the European Arrest Warrant made the extradition of people from one member state almost automatic.

However, politics has intervened. In recent years, the Hungarian and Polish governments have been criticised for adopting increasingly illiberal policies, particularly in relation to judicial independence.

The Hungarian government forcibly retired large numbers of judges and has given political figures greater control over the Hungarian judiciary. In Poland, the government has increased political control of the judiciary and passed a law that forces a third of the supreme court to retire unless they are granted an extension by the Polish president.

These measures have provoked clashes with the EU and the Polish judiciary. The European Commission has begun proceedings against the Polish government and the Polish supreme court has asked the European Court of Justice to rule on whether the forced retirement of judges violates EU guarantees on judicial independence.

These are not minor matters because independent courts and mutual recognition of legal decisions between member states are central to the operation of EU law.

Under EU law, the Irish authorities are required to trust the institutions of other member states. In extradition proceedings, if a court in an EU member state asks an Irish court to surrender someone for trial, the Irish court under EU law has to assume that that person will get a fair trial.

Judicial independence

However, EU institutions have been openly doubting whether the Polish government respects judicial independence. So it was not surprising that the Irish High Court decided that it should ask the European Court whether it should continue to assume that people such as Celmer would get a fair trial if extradited to Poland. This decision caused an avalanche of criticism and abuse from leading pro-government figures in Poland.

The High Court decided it should ask the European Court whether it should continue to assume people such as Celmer would get a fair trial if extradited to Poland

The European Court ruled that the Irish court should verify whether there is a systemic problem in relation to judicial independence and whether there is a real risk that, if extradited, Celmer would suffer a breach of his right to a fair trial. The High Court has now decided to ask the Polish authorities for more information before it decides whether to surrender Celmer to them.

It is difficult to overstate the seriousness of this situation for the EU. Mutual recognition based on mutual trust between member states goes far beyond issues of extradition. Indeed, EU law as a whole is an elaborate web of duties on member states to recognise and enforce each other’s decisions.

The EU single market is heavily dependent on mutual recognition. It is because of the duty of mutual recognition that products that are lawfully manufactured in one member state can generally be imported into another without restriction.

But mutual recognition requires mutual trust. Both the Irish and European courts now appear to be saying that they cannot trust the independence and fairness of the Polish courts. If national authorities cannot trust each other’s decisions then the whole framework of mutual recognition of each other’s decisions that underpins the single market may unravel.

Democratic values

It is difficult for the EU to address this situation. The EU treaties provide a mechanism to strip states in serious and persistent breach of liberal democratic values of their voting rights. However, doing so requires the agreement of all other member states and Poland has made it clear that it will veto any moves against Hungary in this regard and vice versa.

The EU is like a club with a strong bouncer but little security once you are inside the venue

The EU is like a club with a strong bouncer but little security once you are inside the venue. Applicant states are rigorously checked to ensure that they adhere to liberal democratic values but once a state is admitted to the club the mechanisms to ensure they keep adhering to those values are very weak.

The EU treaties appear to be based on the same “end of history” thinking prominent in the 1990s and effectively assume becoming a liberal democracy is irreversible. They are ill-equipped to deal with a situation where an existing EU member state moves away from liberal democracy.

What is more, so much of the EU operates by consensus that should relations between Warsaw and the EU break down completely, a renegade member state can easily paralyse EU decision-making in a wide range of areas.

The High Court ruling in Celmer’s case show how the retreat of liberal democratic values and breakdown of mutual trust between member states means that a broader unravelling of the EU’s mutual recognition-based legal system cannot be ruled out. That represents a much more fundamental threat to the EU than even the hardest of Brexits.

Ronan McCrea is professor of EU and constitutional law at University College London