According to British barrister Jolyon Maugham, one of the petitioners in the "Wightman case", this is a crucial point as if this was not the case then any cancellation (such as following a "People's Vote" or a general election or a decision by British MPs) could depend on the agreement of the other European Union leaders who might decide to set conditions such as the United Kingdom giving up various opt-outs.
The UK should be allowed to reverse Brexit, according to an advisory opinion from the European Union's top court that will fuel the campaign to thwart the divorce.
A leading European legal official has said Britain can unilaterally cancel its withdrawal from the European Union ahead of a key parliamentary debate on British Prime Minister Theresa May's widely criticised Brexit deal. Batten remarked: "The political establishment intends to reverse the decision of the Referendum and betray Brexit at any cost".
In order to revoke Article 50, the opinion says the United Kingdom would have to formally notify the European Council, respect national constitutional requirements - which in the United Kingdom would mean an act of parliament, and finally the revocation would have to take place within the two-year period since Article 50 was triggered.
Since Article 50 is scant on details - largely because the idea of any country leaving the bloc was considered unlikely - a group of Scottish legislators wants to know whether the United Kingdom can pull out of the withdrawal procedure on its own.
Analysts said that if the European Court decides to support this opinion it will reinforce the hand of those who want the United Kingdom parliament to overturn the referendum result and stay in the EU.
In another sign of the government's weakness, lawmakers also passed an amendment giving Parliament more say over the government's next steps if the divorce deal is rejected in a vote on December 11. The reprimand, by 311 votes to 293, marks the first time a British government has been found in contempt of Parliament.
She faces particular challenges from the pro-Brexit faction in her own party, which opposes several aspects of the agreement, including the Northern Ireland backstop, the goal of which is to avoid a hard border on the island of Ireland. Lawmakers were set to vote on a motion finding the government in contempt of Parliament for refusing to publish the full guidance from Attorney General Geoffrey Cox.
The comments raised expectations the Labour party could back putting Brexit to a second vote though it is unclear what impact such a prospect would have on sterling. Mrs May's surrender document will not pass a House of Commons vote, and the obvious result of that would be for a "no deal" Brexit.
"That puts the decision about our future back into the hands of our own elected representatives", said Jo Maugham, one of the lawyers involved in the case. The Bank of England warned last week that a no-deal Brexit could plunge Britain into a severe recession, with the economy shrinking by 8 percent in the months after March 29. An expedited ECJ decision on the case is expected before the end of the year.
Debate over the Brexit deal, which has been widely criticised across Britain's political spectrum, will begin in the United Kingdom parliament's lower chamber House of Commons on Tuesday.