A group of Tory MPs have seized on a government promise made six years ago that parliament should decide the response to a referendum.
In 2010 David Cameron’s government agreed that referendums “cannot be legally binding in the UK… because of the sovereignty of Parliament”.
MPs calling for a parliamentary vote on Brexit say the pledge could strengthen their case, the Independent reports.
Theresa May intends to use the royal prerogative to trigger Article 50 in the spring, bypassing parliament - a plan currently being challenged in court.
But in 2010, ministers declared referendums merely “advisory”, in response to an inquiry by a House of Lords committee.
Mark Harper, who was then the constitutional reform minister, agreed with the recommendation.
“Under the UK’s constitutional arrangements, Parliament must be responsible for deciding whether or not to take action in response to a referendum result”, he said.
The Tory MP Nicky Morgan told the Independent the six-year-old pledge helped her argument for a vote in parliament.
“The referendum was advisory and Parliament has to be responsible for deciding whether or not to take action in response to that result”, she said.
“The 2010 Government made that important commitment and – although the complexion of the Government has changed since - the current Prime Minister was a very important part of that Government.”
The former Tory cabinet minister Ken Clarke said the document was “constitutionally... correct” and shouldn’t be ignored.
“And it’s sensible, because a referendum on a big, broad question tells us nothing about the dozens of issues that have to be tackled by the Government in response to it”, he said.
Tory MP Dominic Grieve said it was “absolutely, abundantly clear” that all referendums are advisory:
“The Government doesn’t have a blank cheque on what model we pursue as we come out of the EU, or our future relationship with the European Union, because the electorate made no pronouncement on that whatsoever,” he said.
May’s spokesperson 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.”
“Triggering Article 50 is therefore something for the Government to deliver.”