The UN - not Mr Blair - had the power to rule that Iraq was not complying with its resolutions.
The Attorney General argued that in law, there was a strong case that the United Nations should determine whether Iraq had ignored the demand that its weapons of mass destruction be destroyed.
The paper is said to have warned that the UN security council, not individual members, should decide whether Iraq had complied with Resolution 1441, passed in November 2002. The resolution itself confirmed that Iraq "has been and remains" in material breach to earlier resolutions, but says further breaches would be reported to the security council "for assessment".
UN Security Council resolution 1441 might not be sufficient legal basis for war.
Lord Goldsmith's advice appears to have warned that the precise wording of resolution 1441 fell short of the legal definition required formally to authorise war. Resolution 1441 said that "the Council has repeatedly warned Iraq that it will face serious consequences as a result of its continued violations of its obligations". However, the use of the term "serious consequences" is not as strong as the term "all necessary means", the international term for military action, which were the words contained in resolution 678 that authorised force in the run up to the first Gulf War a decade earlier.
Lord Goldsmith expressed caution about going to war without a second United Nations resolution.
Lord Goldsmith's opinion is said to have warned Tony Blair that, while he could go to war without a second UN resolution, it would be desirable and "safer" to obtain a resolution explicitly authorising military action.
At the time, ministers were still working frantically to secure a second resolution.
However, the Prime Minister was saying at the time it was London's "preference" to have a new resolution, whilst leaving the door open to action without such a resolution.
Mr Blair was told there were risks in relying on previous UN resolutions to justify military action.
Lord Goldsmith argued that it could be difficult to revive the authority for military action in UN resolution 678 in 1990, given that 678 authorised action to remove Iraq from Kuwait and did not explicitly authorise an invasion of Iraq. Such a caution is important because Lord Goldsmith's final opinion authorising war did revive 678, arguing that "Authority to use force against Iraq exists from the ... effect of resolutions 678, 687 and 1441. All these resolutions were adopted under Chapter Seven of the UN Charter, which allows the use of force for the ... purpose of restoring international peace and security."
Lord Goldsmith pointed to the latest work by Hans Blix and his team of UN weapons inspectors.
Lord Goldsmith's advice was written on 7 March, 2003 as Dr Blix reported that United Nations weapons inspectors were making some progress in Iraq. His report praised Iraq's decision to destroy 34 outlawed missiles as "substantial" and said inspections "may yield results." Dr Blix argued that some Iraqi actions were "active" or "proactive". He noted that inspections based on intelligence tip-offs had found "no evidence". However he did say that Iraq's moves "cannot be said to constitute 'immediate' co-operation. Nor do they necessarily cover all areas of relevance."
Lord Goldsmith said that American statements on the legality of war were not applicable in Britain.
He said that the White House did not face the same legal problems as Britain after the United States Congress had given President Bush special powers to go to war. Mr Bush secured overwhelming votes in both houses of Congress giving the President the right to launch a military strike, even without the backing of the United Nations. They voted to allow him to "use the armed forces of the United States as he determines to be necessary and appropriate ... against the continuing threat posed by Iraq". Washington had insisted that a second resolution was desirable but not necessary.