But in the final part of his conclusion, Cox said that legal risks of Britain being stuck in the backstop remained.
His verdict, due to be published this morning, could be enough to persuade many Tory MPs to swing behind the deal and vote for it this evening. While the anti-Brexiteers have continued to say they'll vote "no" and the staunch May supporters have indicated that they'll likely vote "yes", the most pivotal votes will no doubt be the ERG (a group within the Conservatives who represent the Eurosceptic of the party) and the DUP - whose influence amounts to 10 MPs.
If the deal is voted down again, on the following two days lawmakers are expected to discuss and vote on two amendments.
Supporters of Brexit say while the divorce might bring some short-term instability, in the longer term it will allow the United Kingdom to thrive and also enable deeper European Union integration without such a powerful reluctant member.
The stinging 149-vote defeat stripped away May's control over the course of Brexit and handed it to Parliament, which is divided about what to do next. If the backstop comes into force and talks on the future relationship break down, May said the unilateral declaration would make clear there was nothing to stop London from moving to leave the backstop.
You may have read in the last day that she won a "revised deal" in Monday night talks with European Commission President Jean-Claude Juncker, but all she really got was repeated assurances that no-one in the EU wants the crucial Irish backstop mechanism (explained here) to be permanent, leaving the United Kingdom indefinitely tied into a customs union with the EU if the two sides fail to strike a new trade agreement in the next couple years.
The government's defeat will embolden politicians calling for a second referendum on whether to leave the European Union or remain, though there is no clear majority in Parliament for that course.
"In light of our own legal analysis and others, we do not recommend accepting the government's motion today", group member Bill Cash said.
"But if we ever have to use that insurance policy, it can not become a permanent arrangement and it is not the template for our future relationship", she added. If it is the case that we were ever to get into the backstop. However, the text of the 585-page withdrawal agreement remains unchanged. Others questioned why the assurances were not included in the Withdrawal Agreement. It is legally binding.
A DUP spokesman said: "We note the prime minister's latest statement and update on our European Union exit negotiations".
The EU said there would be no more negotiations with London on the divorce terms, struck with May after two-and-a-half years of tortuous negotiations.
More than two hours later - at 11:40 p.m. - the tired leaders sat down for a joint news conference to announce changes they both hope will now put an end to the tortuous negotiations that have defined the U.K.'s exit from the 28-country bloc.
She had hoped that revisions to a Brexit deal over the Irish backstop, or protocol, secured late last night would offer enough assurances to get her deal through parliament. It is what we do with the second chance that counts. "Because there will be no third chance", Juncker warned.
Ireland's Taoiseach Leo Varadkar said: "The further text agreed yesterday provided additional clarity, reassurance and guarantees sought by some to eliminate doubts or fears of some, however unreal, that the goal was to trap the United Kingdom indefinitely in the backstop".