The new President of the European Parliament, Mr Pat Cox, will announce tomorrow whether he is launching a legal power battle with EU governments - less than three weeks after taking office.
Mr Cox, the first Irishman to be elected President, is considering whether he will take EU governments to the European Court of Justice.
Euro-MPs on the Parliament's Legal Affairs Committee have already voted by a narrow majority to do so - but the final decision rests with the President himself.
EU ambassadors discussed the problem this afternoon without resolving it and now await Mr Cox's pronouncement from Cork in the morning.
The move is being threatened because of a complex piece of EU legislation about company law which has been in the pipeline for years.
Until now it has been negotiated under an EU Treaty Article which gives Euro-MPs an equal say in the outcome, alongside ministers.
But now, as draft laws on a European Company Statute are going through, the ministers have changed the "legal base" - effectively cutting the European Parliament out of the process.
EU officials say the switch is purely administrative: in the EU, proposed legislation which involves harmonising national laws is something in which MEPs have a say.
The planned company statute, which cuts red tape and bureaucracy for firms setting up across the EU, is now deemed not to amount to harmonisation of national law, however, and the basis on which it is being negotiated is being changed.
However arcane the legal point, it highlights the fact that Mr Cox is heading a Parliament which is increasingly sensitive about its powers - or lack of them.
Faced with a Legal Affairs Committee pushing for court action, Mr Cox has been thrown in the deep end, forced to decide whether to go to court and instantly antagonise EU leaders - who hugely welcomed his election earlier this month - or let the matter drop and upset MEPs who want a robust response.
"The final authority rests with me and I will take my responsibilities," Mr Cox said today. "Whatever I do it will not please everyone, but you cannot please all of the people all of the time."