Although her government says it has the right to trigger Article 50 without consulting parliament, it has previously promised that lawmakers will be fully consulted over the subsequent negotiations.
During the High Court hearing, government lawyer James Eadie QC moved on to what was likely to happen at the end of the negotiations, in 2019, saying: "The government view at the moment is it is very likely that any such agreement will be subject to ratification".
They are asking the Lord Chief Justice, Lord Thomas, sitting with two other senior judges in London, to rule that Mrs May has gone wrong in law and is in danger of undermining the sovereignty of Parliament. I don't understand why the content of these rights are not controlled by Parliament'.
The FT reports that in a document to be presented to the UK's Cabinet Office this week, the US Chamber of Commerce warns a post-Brexit UK would need "unfettered access" to the European goods and services market for American companies to continue expansion plans.
"There's a very strong argument for the government allowing the approval of a deal reached, but of course it would prefer a vote after Article 50 is triggered", said Robert Thomas, professor of public law at the University of Manchester.
Deal on greenhouse gas HFCs welcomed by UN
More than 100 developing countries, including China, the world's top carbon emitter, will start taking action by 2024. A5 group includes India, Pakistan, Iran and Iraq - with a baseline of 2024-2026 and a freeze date of 2028.
Asked why the Government had changed its position since 2010, a spokesman for the Prime Minister, said: "Parliament voted by a majority of six to one to hold the referendum - and it is a manifesto commitment of the Conservative Party to deliver on its outcome".
The pound plunged 18 percent since the referendum on concerns over the prime minister's hard-line stance. May has a responsibility to carry out the wishes of the people as expressed in the June vote.
What is Article 50?
Ms Miller was accused of "arrogance" as she demanded that Theresa May stages a vote in parliament before invoking Article 50.
But the Prime Minister has dismissed her calls of those of her supporters - and took the unusual step of dispatching the Attorney General to argue the case in person.
The dispute hinges over whether parliament or ministers have the authority to formally notify Brussels that Britain is withdrawing under Article 50 of the Treaty on European Union (TEU).