However, the government responded on Monday by publishing only a 43-page summary of the advice and taking the unusual step of sending the British Attorney General, Geoffrey Cox, to the House of Commons to make a statement and answer questions from members of parliament.
The Speaker of the House has allowed for an emergency motion on whether the government is in contempt of Parliament for failing to publish the advice in full, adding that there was "an arguable case".
But Transport Secretary Chris Grayling defended the decision not to release the full legal advice.
The sanctions ultimately available include suspending a MP, most likely Attorney-General Geoffrey Cox.
The "Meaningful Vote" on May's Brexit deal is to take place on December 11th and is said to be the most important and historic vote to take place in parliament since the end of the Second World War.
Addressing the Commons at the start of a five-day debate on her proposed Brexit agreement, Mrs May said Brexit divisions had become "corrosive" to United Kingdom politics and the public believed the issue had "gone on long enough" and must be resolved.
Labour's Brexit spokesman Keir Starmer said: "This House has now spoken and it's of huge constitutional and political significance".
Tory MPs Peter Bone and Philip Hollobone backed the contempt motion, along with nine MPs from the DUP - who are supposed to be Mrs May's parliamentary allies.
The Conservative prime minister has consistently refused to say what she plans to do if - as widely predicted - the British Parliament rejects the deal her government reached with the EU.
Yet the text's full publication is unlikely to impact a Brexit deal vote that faces resistance from all sides of a bickering House of Commons.
Pro-EU lawmakers said they had made the prospect of a "no-deal" Brexit less likely by securing an amendment giving Parliament more power to guide the government's next steps if the deal is rejected on December 11.
The government had attempted to have the issue referred to the cross-party Privileges Committee in a prior vote but the proposal was defeated by four votes.
That result - which could prevent a "no deal" Brexit - saw the pound rise back to where it started the day, rounding off a rollercoaster day for sterling.
Reflecting on her personal journey, May added: "I have spent almost two years negotiating this deal".
"This is the deal that delivers for the British people".
She says her deal will maintain close economic ties with the European Union while enabling Britain to trade more freely with the rest of the world and meet voters' demands to reduce immigration.
If, against the odds, May wins the vote, Britain will leave the European Union on March 29 on terms negotiated with Brussels - its biggest shift in trade and foreign policy for more than 40 years.
The ECJ's advocate general Manuel Campos Sanchez-Bordona said the United Kingdom could withdraw its notification to leave the European Union before its exit in March 2019 without needing the approval of the other 27 states.
Downing Street insisted that it was "not a final judgment" and "does nothing in any event to change the clear position of the Government that Article 50 is not going to be revoked".