The government has broken with precedent and published the full text of the attorney general's March 7 legal advice to the prime minister, setting out Lord Goldsmith's cautious approach to the legality of the Iraq war.
Tony Blair authorised the disclosure on Thursday morning, after large parts of the documents were leaked to the media on Wednesday evening.
It was published on the Number 10 website after months of insistence from ministers that legal advice must remain confidential.
Downplaying the U-turn, the prime minister said the media had now "probably got it all anyway". "I see no reason not to publish it," he added.
The document, sent on March 7, 2003, showed Lord Goldsmith confirming that he had discussions on the issue with foreign secretary Jack Straw and former UN ambassador Sir Jeremy Greenstock.
He said they had "given me valuable background information on the negotiating history of resolution 1441".
"I have also had the opportunity to hear the views of the US administration from their perspective as co-sponsors of the resolution.
"This note considers the issues in detail in order that you are in a position to understand the legal reasoning."
As the leaks revealed, the attorney general is cautious about the legality of a possible war with Iraq.
"I accept that a reasonable case can be made that resolution 1441 is capable in principle of reviving the authorisation in 678 without a further resolution," he said.
"The argument that resolution 1441 alone has revived the authorisation to use force in resolution 678 will only be sustainable if there are strong factual grounds for concluding that Iraq has failed to take the final opportunity."
And he said that "a 'reasonable case' does not mean that if the matter ever came before a court I would be confident that the court would agree with this view".
The document adds that if most nations remain opposed to military action then "it is likely to be difficult on the facts to categorise a French veto as 'unreasonable'".
And it highlights the fact that the opinion could change in the light of fresh circumstance, as it apparently did by the time the advice was set out to parliament and Cabinet 10 days later on March 17.
"If we fail to achieve the adoption of a second resolution, we would need to consider urgently at that stage the strength of our legal case in the light of circumstances at that time," Lord Goldsmith wrote.