Government admits new Brexit bill 'will break international law'

The government has admitted that its plan to reinterpret the special Brexit arrangements for Northern Ireland will break international law.

The Northern Ireland secretary, Brandon Lewis, astonished backbenchers when he told the House of Commons: “Yes, this does break international law in a very specific and limited way. We’re taking the powers to disapply the EU law concept of direct effect … in a certain very tightly defined circumstance.”

In a new internal market bill, the government is expected to unveil plans for domestic powers to govern part of the Northern Ireland protocol, something that has threatened to torpedo Brexit talks that resumed in London on Tuesday.

It reportedly led to the resignation of the UK’s top legal civil servant, Jonathan Jones, on Tuesday morning.

Lewis told the House of Commons that what the UK was doing was not that unusual.

“There are precedents for the UK and, indeed, other countries, needing to consider their international obligations as circumstances change,” he said citing changes in the Finance Act in 2013.

But the admission led to a torrent of criticism, including from the former prime minister Theresa May, who questioned whether Boris Johnson was risking the UK’s international reputation as a trustworthy nation.

“How can the government reassure future international partners that the UK can be trusted to abide by the legal obligations of the agreement itself?” she asked in an exchange with Lewis during an urgent question in the Commons on the latest developments.

The Irish foreign affairs minister, Simon Coveney, said the latest revelations were “gravely concerning”.

Coveney, who was instrumental in the negotiations about the Irish border, said he could not understand why the UK was seeking to create a “safety net” given the Northern Ireland protocol was specifically “designed and empowered to work in all circumstances”.

“It is surely not too much to ask for the UK to implement the withdrawal agreement which it agreed to,” he told the Dáil Éireann, Ireland’s lower house of parliament.

Johnson’s move to try to override part of the Northern Ireland protocol has put Brexit talks at risk but Lewis told MPs the new legislation, which would “clarify” part of the special arrangements on Northern Ireland, was designed as “limited and reasonable steps to create a safety net” in the event that talks collapse.

Related: UK's top legal civil servant quits 'over Brexit deal changes'

The shadow Northern Ireland secretary, Louise Haigh, accused the government of using the region as a “political football”.

She also questioned whether the government would be asking ministers to break the ministerial code and vote for the internal market bill, the vehicle for the Brexit changes, due to be tabled in Westminster on Wednesday.

Sir Robert Neill, the Conservative MP for Bromley and Chislehurst and chair of the justice select committee, said “the rule of law is not negotiable” and an international treaty signed by the government should not be breached.

Claire Hanna, the SDLP MP for Belfast South, implored Lewis not to “use the threat of a border in Northern Ireland” as a “cat’s paw in this or any other negotiation”.

The DUP North Antrim MP, Ian Paisley, accused the government of having a “tin-foil spine” in failing to stand up to its critics, while his colleague Sammy Wilson, one of the most vocal critics of the Brexit deal, said: “We still don’t know the depth and breadth” of the checks in Northern Ireland.

The president of the Law Society of England and Wales, Simon Davis, said: “The rule of law is not negotiable.

“Our commitment to the rule of law is key to attracting international business to the UK and to maintaining faith in our justice system.”

Government sources claimed the move would not breach the ministerial code because the obligation on ministers to comply with international law was removed from the guidance in 2015 by David Cameron.

However legal experts, including David Anderson, a member of the House of Lords EU security and justice sub-committee, said the code still mandated that ministers uphold international law after a court of appeal ruling in 2018 concluded ministers had an “overarching” duty to do so.

Lewis urged the critics to wait until Wednesday to see what was in the bill.

“I think it would be wholly wrong for the UK government not to take the approach to ensure that there is a safety net should [Brexit talks’] fail, to ensure that in January businesses and people know they’ve got the contents of a structure in place to deliver on our promises.”

He said the bill was designed to deliver the government’s promise that Northern Ireland traders would have “unfettered access” to Great British markets.

However he batted away a question from Hilary Benn, the chair of the Brexit select committee, who demanded to know if, as expected under the protocol, businesses from Great Britain would have to fill in paperwork, including entry summary declarations, if sending goods to Northern Ireland.

That, said Lewis, was being discussed by the specialised EU-UK committee set up under the withdrawal agreement.