Lord Chief Justice for England and Wales John Thomas. Reuters The Lord Chief Justice said he was "baffled" by one of the UK government's key arguments on the final day of the blockbuster Article 50 legal battle.

Three of the UK's most senior judges met in the High Court to hear arguments on whether Theresa May's government is legally required to pass an act of parliament before triggering Britain's withdrawal from the European Union.

Jason Coppel QC, representing the government, argued that EU citizenship rights, which Brits currently enjoy, have never been part of parliament's decision-making remit. He added that "none" of the rights Brits have as EU citizens would be affected by Article 50 being triggered.

Basically, he argues, that the UK parliament has never been under obligation to consider or discuss EU citizenship rights in parliament, so any change to the current situation does not need approval granted by MPs.

Lord Chief Justice Thomas, the most senior judge in the country, said he was "baffled" by this arrangement and suggested that EU citizenship rights, which will be lost once Article 50 is invoked, are a matter for parliamentary consultation.

"I'm baffled," Lord Thomas said. "These rights are under treaty. If amending the treaty, parliamentary approval is needed. So, I don't understand why the content of these rights are not controlled by parliament?"



These rights are under treaty. If amending the treaty, parliamentary approval is needed.

Coppel spoke alongside James Eadie QC, who was representing the government. He argued that parliament had already had a big say in the referendum process and fallout.

"There has already been considerable parliamentary involvement - in the 2015 act and the opposition motion tabled last week - and there will be in the future," he said.

Lord Pannick, representing lead claimant Gina Miller, who Business Insider interviewed in August, said the government had "no answer" to the argument that triggering Article 50 would lead to rights being destroyed without parliament's approval.

"There is no dispute, that once notification is given, there is a direct causal link between notification and the removal of statutory rights ... the consequence of notification is to destroy rights and take the preservation of rights out of parliament's hands. This cannot be done. By the time parliament comes to look at the matter, the dye will already be set."

Tuesday marked the final day of the High Court battle which got underway on Thursday.

If the judges rule in the claimants' favour, Prime Minister May must pass an act of Parliament before invoking Article 50, rather than simply exercising prerogative power. A decision is expected in mid-November.

The claimants are expected to launch an appeal to the Supreme Court if the judges rule against them. This would likely force the government to push back its March deadline for triggering Article 50.