An internal note from Tony Blair that Iraq was in breach of a UN Security Council resolution also played a part in the decision to invade. Forced by Richard Thomas, the Information Commissioner, to disclose more detail about the decision, the office of Lord Goldsmith, QC, the Attorney-General, spelt out who he had consulted and relied upon for advice before declaring that an invasion was covered by international law.

One of the main influences came from a visit to Washington on February 10, when Lord Goldsmith met John Bellinger, then senior associate counsel to President Bush and legal adviser to the National Security Council.

Lord Goldsmith told Parliament on March 17, 2003, three days before the start of the invasion, that, despite the failure to win a second resolution from the Security Council authorising force, military action was justified on the basis of three existing resolutions, the last of which was Resolution 1441.

In yesterday’s disclosure, detailing the background to Lord Goldsmith’s advice to the Government, it was acknowledged that his discussions with lawyers for the Bush Administration who had been involved in drafting and negotiating Resolution 1441 had helped to clear up his doubts about the legal grounds for using force. The disclosure document revealed that Lord Goldsmith had taken into account the view from Jack Straw, then Foreign Secretary, Sir Jeremy Greenstock, then Britain’s Ambassador to the UN, and the US Administration that “a further decision of the Security Council was not required”.

Mr Blair also made clear his view that Iraq had materially breached Resolution 1441 by continuing to develop weapons of mass destruction, and Baroness Morgan of Huyton, then director of government relations, wrote an e-mail on March 15 stating for the record that the Attorney-General was happy with Mr Blair’s stance.

Elizabeth Wilmshurst, deputy chief legal adviser to the Foreign and Commonwealth Office, disagreed and resigned when the Government decided to go ahead. Government legal sources said that Lord Goldsmith had not consulted her but had taken into account advice from the Foreign Office.

The publication of the background to Lord Goldsmith’s advice came after calls for the Information Commissioner to order the release of sensitive documents. The advice on March 7, 2003, was published last year after a version was leaked.

Mr Thomas decided that it was right to serve an enforcement notice, requiring a full disclosure statement, without all the documents having to be published. It was in the public interest to understand and challenge government decision-making, especially on matters “of such gravity and magnitude as the decision to commit the country to military action”, he said. Lord Goldsmith’s March 7 advice was “significantly more equivocal” than his statement to Parliament on March 17.

The Attorney-General’s office said he had been trying to decide whether Resolution 1441 could in principle revive the authority for using force in the original Resolution 678, agreed in 1990 when Iraq invaded Kuwait. Lord Goldsmith concluded that there was a lawful basis without a second resolution, even though his March 7 advice had suggested that the safest course would be to have a resolution mandating force.

Dominic Grieve, the Shadow Attorney-General, said: “The critical thing that emerges is the impact of a written assurance from the Prime Minister that there was a material breach of 1441. It seems to confirm . . . that the Attorney-General was misled by the Prime Minister.”

Sir Menzies Campbell, the Liberal Democrat leader, said: “There is nothing here to indicate that there was new intelligence on weapons of mass destruction or legal arguments to justify the change of mind.” The “irresistible implication” was that it was from “political pressure”.

COUNTDOWN

How Lord Goldsmith reached his decision in 2003

How Lord Goldsmith reached his decision in 2003

January 23 Met Sir Jeremy Greenstock, permanent represenative to UN

February 10 Met US government lawyers

February 27 Met Jonathan Powell, Sir David Manning and Baroness Morgan; notified them a reasonable case could be made for military action without further resolution

March 7 Issued secret advice saying safest legal course was a further UN resolution; a reasonable case could be made based on existing resolutions

March 13 Attorney-General discusses matter with his legal secretary. Record of meeting says Lord Goldsmith had “particular regard” for discussions with Sir Jeremy, representatives of US Administration and negotiating history. Agreed to confirm to MoD military action would be lawful

March 14 Legal secretary wrote to Tony Blair’s private secretary seeking confirmation, previously given orally, that it was Mr Blair’s view that Iraq had committed further material breaches of UN resolutions

March 15 No 10 confirmed this

March 15 Baroness Morgan confirmed Attorney-General happy with this confirmation. He was to make clear there was legal basis for action

March 17 Attorney-General published statement to Parliament saying authority to use force existed under current UN resolutions

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