THE Supreme Court insisted that it is not vying to “overturn the referendum result” as the high-profile Brexit challenge came to a close yesterday.

Court president Lord Neuberger said that only “constitutional issues” surrounding the process by which Britain leaves the EU will be decided.

The 11 judges will consider submissions by lawyers and a judgement for the landmark case will be handed down in January — just two months before PM Theresa May plans to trigger Article 50.

Lord Neuberger added that the judges would work to

resolve the case “as quickly as possible.”

The four-day proceedings come after the High Court ruled against the government last month, saying that Ms May lacked the legal power to start the two-year withdrawal process without a vote by MPs.

The lead claimant of the case, Gina Miller has faced threats and has been under police protection over the four-day appeal.

Ms Miller and other opponents to Ms May’s plans say that an Act of Parliament is needed to authorise leaving the EU.

Government lawyer James Edie QC told the Supreme Court that ministers have the

right to trigger Article 50 because they have the royal prerogative power to do so.

He added that if prerogative power cannot be used to conduct British foreign affairs then a denial by the courts would “have very serious consequences.”

Ministers were accused by Richard Gordon QC — acting for the government of Wales — of trying to use the royal prerogative to “drive through” constitutional changes of a “seismic nature.”

He added that having a “treaty-making power” did not mean there was a power to “dispense with laws, or subvert statutory schemes or crucify human rights.”

Mr Gordon continued: “Wales is not here because it wants either to stop or to stall Brexit, or the implementation of Brexit. It is here precisely because the constitutional issues at stake go far beyond Brexit.”

Manjit Gill QC — acting for nationals of the European Economic Area — said it is important that Parliament should be involved in triggering withdrawal.

Helen Mountfield QC — for the crowdfunded “People’s Challenge” — said the people she represented “consider EU citizenship

a fundamental part of their identity” and that only Parliament should be able to deprive them of domestic law rights.

A total of 448 MPs signalled on Wednesday that they would be in favour of invoking Article 50 by March, compared to 75 opponents.