The European court has already held the hearing, taking evidence from the group of lawmakers who said they wanted clarity to help decisions made by the U.K. Parliament. The British government has opposed the case, arguing it is a politically-motivated bid to frustrate Brexit.
The court also heard from lawyers representing the European Commission and Council of the European Union — which is the executive arm of the EU and the institution that represents member states’ governments. They argued that revoking Article 50 should involve unanimous agreement from the other 27 nations.
The EU is worried that allowing a country to trigger Article 50 and then reverse the decision with no additional input could become a tool for those unsatisfied with the policies of Brussels. For the U.K. government and pro-Brexit politicians, there are likely concerns it could pave the way for a second referendum, giving the public an option of remaining in the EU.
The non-binding opinion of Advocate General Manuel Campos Sanchez-Bordona was issued on Tuesday. But the full ruling will follow within days, though it’s expected that the opinion of the advocate general will almost certainly be followed by the panel of judges.