There are concerns a bid by the UK Prime Minister to override portions of his Brexit deal could break international law.
Mr Johnson pressed on in his bid to publish new laws that would "annul" parts of the Brexit withdrawal agreement, despite a Tory backlash led by predecessor Theresa May.
Boris Johnson's chief negotiator declared, this week was "make or break" if they were to avoid a "no deal".
The government outlined controversial Brexit legislation to give themselves the powers to limit checks and EU influence in Northern Ireland in the event that no trade deal could be struck between the UK and EU by the end of the year.
Under the treaty - signed last year - the UK agreed to determine the issue jointly with the EU, but ministers claimed they needed to take unilateral powers to avoid jeopardising peace in Northern Ireland.