Proposed legislation to allow the UK to unilaterally rip up Brexit arrangements for Northern Ireland at the risk of a trade war with the EU passed the second reading stage in the House of Commons on Monday night. As expected the Northern Ireland protocol bill passed its first hurdle, with MPs voting 295 to 221 in favour despite heavy criticism from some Conservative backbenchers, including former prime minister Theresa May, who said the move is illegal and unnecessary. The second reading was the first opportunity MPs have had to vote on the controversial proposals, which the foreign secretary, Liz Truss, said were “legal and necessary”. Boris Johnson predicted earlier on Monday that the laws could go through “fairly rapidly” and be on the statute books by the end of the year. It is now expected to be fast-tracked through parliament with a condensed committee stage of just three days, instead of the usual two or three weeks. Opening the debate, Truss said there was “strong legal justification” for it and that the UK remains committed to seeking a negotiated solution. She repeated that her “preferred option” to solve the dispute over Brexit trading arrangements was negotiation, but that she had no choice but to press ahead with legislation as the EU refused to reopen the text of the protocol. The Northern Ireland secretary, Brandon Lewis, said the bill was designed to ensure the same free flow of goods from Great Britain to Northern Ireland “as from Great Yarmouth to Carlisle”. The bill was condemned by the shadow foreign secretary, David Lammy, who said it was illegal and would shred the UK’s international reputation as a law-keeper. He also told MPs that the bill was the slowest path to resolving the dispute with Brussels and exposed dishonest motives by the Conservative party. “The government has chosen a route that will take months of parliamentary wrangling to fix,” he said, including on complicated “issues like unequal VAT rates” that no one would consider a matter of “grave peril” to the UK. “This bill is damaging and counterproductive. The strategy behind it is flawed. The legal justification for it is feeble. The precedent it sets is dangerous, and the timing could hardly be worse. It divides the United Kingdom and the European Union.” In an excoriating attack May said the bill was unjustified and her colleagues who supported Johnson’s deal “should have listened to the DUP (Democratic Unionist party)” during the debates on it “because they made their position on the protocol very clear at that point and it was not positive”. Former international aid minister Andrew Mitchell said it “brazenly breaks a solemn international treaty” and could “trash” the UK’s international reputation, while Simon Hoare, the Conservative chair of the Northern Ireland affairs committee, asked if the bill was “a muscle-flex for a future leadership bid” by Truss. He also criticised a feature of the bill that would give ministers alone the right to devise new laws replacing those underpinning the Northern Ireland protocol. There were 17 such “Henry VIII” powers giving “unspecified powers” to ministers, Hoare said. “It is not a well-thought-out bill, it’s not a good bill, it’s not a constitutional bill,” he said, adding that it was also “a failure of statecraft” in London and Brussels. Hilary Benn, the former Labour chair of the Brexit select committee, took a sideswipe at the foreign secretary by reminding the House that she campaigned for remain in the run-up to the Brexit referendum. To cheers from the Conservative side, Truss said she was backing Brexit because she was a “patriot”. This prompted Hoare to criticise her for “impugning” the patriotism of those who opposed the bill. Benn said the EU also “needed to move” to resolve the situation, but said it was “very frustrating” to hear the Irish foreign minister, Simon Coveney, say repeatedly on radio that the EU had made similar proposals to those made by the Tories in the bill. “This is a bill born of desperation rather than principle,” he said. “It’s time for the UK, together with the EU, to get back round the table and sort this out.” Truss told the house that the bill would not disrupt the common travel area, which was working. The bill would create a “green channel”, free of checks, for goods passing from Great Britain to Northern Ireland that are not destined for the Irish republic; allow products to be sold in Northern Ireland under either EU or UK rules; and give UK ministers more power to alter tax and spending policies in Northern Ireland. This is similar to the “express lane” proposed by the EU.