Roundup: British PM has power to trigger Brexit, Supreme Court told

British Prime Minister Theresa May's government has the power to start the process to take Britain out of the European Union, the Supreme Court in London was told Monday.

In what was been called the battle for Brexit, the highest court in Britain has been asked to decide whether May's government or politicians in Parliament has the power to start the process of leaving the EU.

The British public voted to leave the EU in a referendum in June by a 52-48 margin, with the process of how the exit process should be triggered becoming a battleground between May and her team and the politicians in the Houses of Parliament.

The decision has been left to the 11 Supreme Court judges after the High Court ruled against the government and said parliament had to be involved in the process.

Attorney General Jeremy Wright, a law barrister as well as a Conservative MP, made the opening shots in what is one of the most important cases in British legal history.

Wright, representing Theresa May and her government, said the case had a great constitutional significance, generating interest both inside and outside the courtroom.

Wright said the June 23 referendum was conducted in the universal expectation, including in Parliament, that the government would implement its result.

He said the then foreign secretary told the House of Commons that the referendum bill had one clear purpose, to deliver on the promise to give the British people the final say on EU membership in an in-out referendum.

Wright said the High Court concluded that the process could not lawfully be begun by the government using prerogative powers, but only by further legislation in parliament.

The hearing will not be deciding whether Britain should leave or remain in the EU, as the referendum has voted for Brexit. Instead it will decide how Britain should leave, sparking fears that parliamentarians opposed to Britain leaving may delay or sabotage the Brexit program.

Wright said the British parliament will be closely involved in the process of Britain's withdrawal from the EU over the coming months and years, through parliamentary debate and scrutiny.

Later this week opponents of the government's case, mainly wealthy investment manager Gina Miller and hairdresser Deir Dos Santos, will be challenging the court to accept that parliament as a sovereign body should take the decision on triggering Britain's exit.

The main opposition Labor Party has said if the court rules that parliament should be involved in the process it will respect the referendum decision.

But the party has said it will try to amend the triggering process known as Article 50 bill to ensure Britain retains access to the European single market access and workers' rights are protected.

People from both the remain and leave camps gathered outside the historic court building which stands just 200 meters from the Houses of Parliament.

Away from the courts, media reports say government officials are preparing to put a brief parliamentary bill before parliament in January if the court does decide that MPs and the House of Lords must be involved in triggering the exit process.

The government's insistence that it has the power without parliamentary approval will again dominate the court proceedings on Tuesday. The judges will deliver their verdict early January. Endit