In its seventh defeat on flagship Brexit legislation, the House of Lords backed an amendment to the European Union (Withdrawal) Bill giving Parliament a decisive say on the outcome of the Brexit negotiations.
Peers voted by 335 to 244 in favour of the amendment, with 19 Conservative rebels defying the government including former deputy prime minister Lord Heseltine.
The government said it would now “consider the implications” of the Lords defeat, claiming it would weaken the Prime Minister’s hand in negotiations with the European Union and could even give MPs the power to delay Brexit indefinitely.
Changes to legislation in the House of Lords can be stripped from the Withdrawal Bill when it returns to the Commons, but the government’s narrow majority increases the risk from defeats in the second chamber.
Shadow Brexit secretary Sir Keir Starmer said the Lords vote was a “hugely significant moment” and would help to avoid the risk of crashing out of the EU without a deal.
Brexit minister Lord Callanan said: “We are disappointed that the House of Lords has voted for this amendment in spite of the assurances we have provided.
“What this amendment would do is weaken the UK’s hand in our negotiations with the EU by giving Parliament unprecedented powers to instruct the government to do anything with regard to the negotiations – including trying to keep the UK in the EU indefinitely.
“It is absolutely right that Parliament is able to scrutinise the final deal, and that is why we have already committed to giving both Houses a vote on the final deal.”
Sir Keir urged the Prime Minister to accept the cross-party amendment, warning that there was “no majority in Parliament for a no-deal Brexit”.
He said: “If Parliament votes down the Article 50 deal, then Parliament must decide what happens next. Under no circumstances can the Prime Minister be given a blank cheque to crash the UK out of the EU without a deal.”
SNP MP Stephen Gethins MP said the defeat was the “most damaging” the government had suffered.
“There is no majority in Parliament – or the UK – for a hard Brexit and the Tories will only face more humiliating defeats if they don’t accept the need to change course.”
Crossbench peer Lord Malloch-Brown, chairman of the pro-EU Best for Britain campaign, said: “This feels like a turning point. This is a massive defeat for the Government.”