The Internal Market Bill aims to ensure Britain's four constituent nations can trade freely with one another after leaving the EU.
"Passing an act of Parliament and going on to break an worldwide treaty obligation should be the very last thing you contemplate, an absolute last resort". In November 2018, he resigned from all party and government positions over the draft Withdrawal Bill and concerns about the backstop.
But Johnson claimed the European Union was ready to go to "extreme and unreasonable lengths" and to use these arrangements to "exert leverage" in the trade negotiations.
"So I have grave misgivings about what is being proposed".
Ed Miliband has said that opposition to the Bill is not about remain or leave and is not party political, but is a matter of upholding worldwide law.
Even some Brexit-backing Tories are unhappy, with one, Charles Walker, saying: "I'm no fan of the European Union. but surely we have to exhaust all other options before we press the nuclear button". He accused the European Union of making "absurd" threats to stop food moving from mainland Great Britain to Northern Ireland.
However, Martin warned the British Government that the EU's response to the Internal Market Bill would be "firm and strong".
"I think it is wrong that the British Government or our Parliament should renege on an agreement on which we gave our solemn word".
"No British minister should solemnly undertake to observe treaty obligations with his fingers crossed behind his back", Johnson's former Attorney General Geoffrey Cox, who is influential with colleagues, said in The Times newspaper.
"The EU has not always been the constructive partner that all of us might have hoped", Gove said in closing remarks at the end of a House of Commons debate on the controversial Internal Market bill.
"What ministers should not do, however provoked or frustrated they may feel, is to take or use powers permanently and unilaterally to rewrite portions of an agreement into which this country freely entered just a few months ago", he said.
On Sunday former PM's John Major and Tony Blair united to urge MPs to reject the "shaming" legislation, saying it imperils the Irish peace process, trade negotiations and the UK's integrity.
Mr Johnson warned that Brussels could "carve up our country" without his new Bill, as he tried to quell the dozens of senior Tories and backbenchers planning on voting against the legislation.
"It raises questions that go far beyond the impact on Ireland, the peace process and negotiations for a trade deal - crucial though they are".
Despite Mr Johnson's attempts to drum up support, Tory rebels suggested their numbers were growing and opinions were only hardened by Mr Johnson's increased rhetoric.
If, as expected, it is passed in its second reading on Monday, there will be four more days of debate on the bill's fine print - lasting into Tuesday of next week.
But a rebellion could come later with Commons justice committee chairman Sir Bob Neill's amendment, which he said would impose a "parliamentary lock" on any changes to the Withdrawal Agreement.