Attorney General Jeremy Wright QC is due to lay out the government's argument in the Article 50 case tomorrow.
The case, which started in the High Court last Thursday, has been brought to decide whether an Act of Parliament needs to be in place before government triggers Article 50.
However, lawyers for government are expected to argue it has prerogative powers to start the UK's formal withdrawal from the EU without consulting parliament first.
In particular, Wright is expected to point out that the 2015 Act authorising the referendum was passed on the basis the electorate's wishes would be carried out.
In a statement issued before the start of the case, Wright said: "The country voted to leave the European Union, in a referendum approved by Act of Parliament. There must be no attempts to remain inside the EU, no attempts to re-join it through the back door, and no second referendum."
Also appearing for the government in the case are James Eadie QC, Jason Coppel QC, Tom Cross and Christopher Knight.
The hearing is expected to continue into Tuesday and a final decision is not expected for some time.
Should the losing party wish to appeal, a leapfrog process is already in place to allow the case to skip over the Court of Appeal and direct to the Supreme Court for a hearing in December, which would bring this case to an end comfortably before Article 50 is expected to be triggered.
Speaking for the lead claimant, businesswoman Gina Miller, last Thursday, Lord Pannick QC noted there would be no going back for the UK once the Article 50 button was pressed, underlining the constitutional importance of the case.
Meanwhile, senior backbenchers, including former Labour leader Ed Miliband, are to table a motion for a parliamentary debate on Article 50.
Miliband will be joined by former Lib Dem leader Nick Clegg and a former junior Home Office minister, Nick Herbert, with a motion set to be agreed in the coming weeks.
Their efforts are being coordinated by Open Britain, the successor group to the EU referendum's official Remain campaign, but will also be backed by Stephen Philips, a Conservative Brexit backer who last week accused Theresa May of "tyranny" over her failure to offer parliament a role in the process.
The motion will call the government to publish for debate the central tenets of its negotiating stance ahead of Article 50 being triggered, although MPs are yet to agree on whether they should be allowed a vote on that position.