Separation of powers
Speaking at the Institute of International and European Affairs (IIEA) yesterday, Mr Justice Clarke said the move would raise questions about the separation of powers.
"If you're simply trying to overturn a decision and say, 'we don't like that decision', and it is hereby no longer the decision and something else is the decision, I think that's a fundamental breach of the separation of powers, and would be a serious attack on the rule of law," he said.
"Perhaps (it is) a more direct attack than those which are criticised in some countries where you don't change the decisions, but change the judges in the hope that the new judges will come up with different decisions. "But to actually directly change the decisions of them would, I think, be quite a direct attack on the rule of law.
"Whether they go down that route is perhaps another day's work, we'll have to see what actually happens, rather than what people threatened might happen. One sometimes could be forgiven for thinking that some of this is just playing to a certain constituency, and whether it actually manifests in real change may not be quite as clear as the rhetoric might suggest."
The European Court of Justice (ECJ) recently levied a €1 million daily fine against Poland after its constitutional tribunal ruled that basic principles of EU law were incompatible with the Polish Constitution.
Mr Justice Clarke said the EU was in "unchartered legal waters" on the remedies for rejections of the supremacy of EU law, and said he wondered what effect such fines would have on a large country.
Legally permissible
"I think, to be effective, it would need to be more than a fine of a million [euro] a day, but exactly what is legally permissible is itself a question, and you don't want to enforce the rule of law by breaking the rule of law yourself, so there does need to be a proper legal basis for any measures which are adopted," he said.
"That isn’t necessarily very easy."
The ECJ has also launched infringement proceedings against Germany over an alleged breach of the supremacy of EU law.
Mr Justice Clarke said the findings of the German and Polish courts "water down" the supremacy of EU law. "They certainly do from the perspective of the national constitution of those countries," he added.
"As a matter of European union, it is clear that the courts of the member states are required to disapply national laws, including national constitutional laws, which conflict with European Union law.
"One of the problems here is that we're sailing in somewhat uncharted legal waters as to what remedies there are for these problems.
Explicit measures
"The treaties don't have absolutely explicit measures that can be adopted. One of the problems, of course, is [that] the easy way of dealing with it would be a measure adopted under the treaties by all of the other member states.
"But as long as you have two member states that aren't toeing what would be perceived to be the Brussels line, then the practical possibility of adopting those measures, which are the only ones expressly recognised in the treaties, is no longer there."
Rule-of-law questions in other member states could affect judicial confidence in Ireland, he said.
"Ultimately, every legal system needs some court that makes the final call," he said.
Mr Justice Clarke also warned of the “very rapid unravelling of the coherence of the European Union legal space, given populist challenges that EU law should apply across the board".
Anything that deviates from this raises the possibility of creating "different and incompatible results", which could challenge the coherence of the European legal space, with member states potentially altering their constitution to oppose proposed EU measures.
"We’ve come, perhaps, in recent years to realise that what seemed like extreme examples, do have a tendency to come more to pass in the current era than perhaps might have been the case in the past," he said.
How EU law is applied in national constitutions varies across Europe, and needs to be carefully examined, he said.
"Pretending it will go away won’t make it go away," he added.