The House of Lords has insisted the triggering of Article 50 is reversible
And it could mean that the unelected members will put a spanner in the works as they probe how they believe Brexit will effect Britain.
The Lords have made no secret of their desire to scrutinise how the UK Government carries out the democratic will of the people by leaving the European Union by tabling many debates since the vote last year.
Now after the UK Supreme Court ruled that according to the law they have a say on the issue, there is increased fears they could prevent the country from leaving altogether.
Following a debate last year the House of Lords concluded "there is nothing in Article 50 formally to prevent a Member State from reversing its decision to withdraw in the course of the withdrawal negotiations”.
Now as the Government has to take its White Paper to the Commons and the Lords, there could be major delays on the Triggering of Article 50, especially if the SNP keep to their pledge to apply for 50 amendments.
The House of Lords committee report stated in its conclusion: "If a Member State decides to withdraw from the EU, the process described in Article 50 is the only way of doing so consistent with EU and international law.
"There is nothing in Article 50 formally to prevent a Member State from reversing its decision to withdraw in the course of the withdrawal negotiations. The political consequences of such a change of mind would, though, be substantial."
"Withdrawal from the EU is final once the withdrawal agreement enters into force.
Theresa May wanted to trigger Article 50 in March, but the SUpreme Court's decision might delay her
"Article 50 makes clear that if a State that has withdrawn from the EU seeks to rejoin, its request shall be subject to the same procedures as any other applicant State."
The House of Lords was acting on evidence gleaned from Sir David Edward, a Scottish lawyer and academic, and former Judge of the Court of Justice of the European Communities.
He said: “It is absolutely clear that you cannot be forced to go through with it if you do not want to: for example, if there is a change of Government."
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Oxford-based Professor Derrick Wyatt supported this view.
BREXIT: Supreme Court Ruling
Tue, January 24, 2017
Britain's most senior judges ruled that Prime Minister Theresa May does not have the power to trigger the formal process Article 50 for the UK's exit from the European Union without Parliament having a say.
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Lead claimant in the Article 50 case, Gina Miller delivers a statement outside the Supreme Court in London
He said: “There is nothing in the wording to say that you cannot (reverse).
"It is in accord with the general aims of the Treaties that people stay in rather than rush out of the exit door.
"There is also the specific provision in Article 50 to the effect that, if a State withdraws, it has to apply to rejoin de novo.
"That only applies once you have left. If you could not change your mind after a year of thinking about it, but before you had withdrawn, you would then have to wait another year, withdraw and then apply to join again.
The Lords have made no secret of their desire to scrutinise how the Government delivers Brexit
"That just does not make sense. Analysis of the text suggests that you are entitled to change your mind.”
Britain's top lawyers are pouring over aspects of the judgement now as the Government plots a way forward.
Rustom Tata, Chairman of DMH Solicitors and an expert on Britain's relationship with the EU said last year that he believed there could still be an uphill struggle.
Mr Tata said: "It must remain a possibility that Brexit might not happen.
"I can't see it making it any easier or quicker.
"It makes our negotiations extremely difficult because every aspect on the table will be subject to scrutiny."