While the Advocate General's opinions are not binding, the court tends to follow them in its final rulings.
He has recommended giving the British parliament the right to unilaterally revoke the withdrawal process, offering a third way of "remaining in the European Union in the face of an unsatisfactory Brexit".
Clearly not trusting the rest of the European Union to agree with Britain if Parliament voted to reverse Brexit, the group petitioned the ECJ for the unilateral right to declare the United Kingdom under the continuing control of the exact same European Union that could not be counted upon to serve their interests in the first place.
But the court's opinion is another headache for the Conservative prime minister as she battles to win Parliament's backing for the divorce deal she has agreed with the EU.
"That possibility continues to exist until such time as the withdrawal agreement is formally concluded", it said in a statement. Batten remarked: "The political establishment intends to reverse the decision of the Referendum and betray Brexit at any cost". The full courts ruling should be available much more quickly than normal because the court is dealing with the case on an expedited basis.
Theresa May is opening five days of Brexit debate on her deal in Parliament today, before MPs get to vote on the agreement on Tuesday, December 11.
May planned open the debate by arguing that members of Parliament must back the agreement to deliver on the voters' decision to leave the European Union and "create a new role for our country in the world".
Britain can unilaterally cancel Brexit, without getting the EU's permission, a senior legal advisor has told the European Court of Justice (ECJ), if the Article 50 process is revoked before the 29 March 2019 deadline for leaving the bloc.
The case was brought before the ECJ by Scottish politicians opposed to Brexit.More news: Saudi crown prince visits Algiers without meeting president
Who has brought the case?
Lawyers for the EU Council and the European Commission also argued that Article 50 could only be reversed by a unanimous decision of all 28 EU capitals.
Two attempts by the UK Government, which is contesting the case, to appeal against the referral to the European court were rejected.
Although the Advocate General's opinion is non-binding, the ECJ follow his opinions in the majority of cases.
Michael Gardner, a partner at law firm Wedlake Bell, said: "This will come as a huge boost to Remain campaigners who wish to stop Brexit".
Legal representatives for the UK Government believe the case is inadmissible as it deals with a hypothetical situation, since the Government's policy is not to revoke Article 50.
Noting the Vienna Convention on the Law of Treaties, the legal opinion states "notifications of withdrawal from an worldwide treaty may be revoked at any time before they take effect".
Writing in The Guardian, Maugham suggested Parliament - which in the matter of opinion on the European Union does not represent the British people and is predominantly pro-Remain - could ignore the referendum and vote to cancel Brexit, writing: "One option is for MPs to just cancel the article 50 notice without a further referendum".