The government will publish its full legal advice on Theresa May’s Brexit deal after MPs found it in contempt of Parliament for not doing so.
The Commons supported a motion, backed by six opposition parties, demanding full disclosure, by 311 votes to 293.
Labour demanded the attorney general’s advice should be released ahead of next Tuesday’s key vote on Mrs May’s deal.
In response Commons Leader Andrea Leadsom said the government “would respond” on Wednesday.
She told MPs she would refer the issue to Commons Privileges Committee to establish the decision’s constitutional repercussions.
Commons Speaker John Bercow said it was “unimaginable” MPs would not now get to see the information before they decided whether to accept or reject the agreement with the EU.
An attempt by ministers to refer the whole issue, including the government’s conduct, to the committee of MPs was earlier defeated by four votes.
The privileges committee will also decide which ministers should be held accountable and what sanction to apply, from a reprimand to suspension.
The move came as Theresa May prepared to sell her Brexit agreement to MPs at the start of five days of debate on the agreement struck with the EU.
The Attorney General Geoffrey Cox published a summary of the advice on Monday but said that full publication would not be in the national interest.
Labour’s Sir Keir Starmer said Tuesday’s vote had “huge constitutional and political significance” and it was “unprecedented” for ministers to have been found in contempt.
Andrea Leadsom said the matter had raised “serious constitutional issues”.