Theresa May’s Brexit backstop plan risks a “stalemate” and “protracted rounds of negotiations” with the EU, the full legal advice on her deal says.
The Democratic Unionists said this would be “devastating” for the UK.
But Mrs May rejected SNP claims she has misled Parliament on the issue.
Ministers were forced to publish Attorney General Geoffrey Cox’s full advice after ministers were found to be in contempt of Parliament on Tuesday for providing only a legal overview earlier this week.
Speaking in the Commons, the prime minister said there was “no difference” between the two documents and the legal position on her proposed “temporary” customs arrangement with the EU was clear.