The latest row: how it started, what it shows, and where it is going next

What is this row all about?

What is this row all about?

A resignation letter written by Elizabeth Wilmshurst, a former senior Foreign Office legal adviser, has been published. It confirms the Attorney General changed his mind about the legality of the Iraq war just before the 2003 invasion. Her letter was released on Wednesday under the Freedom of Information Act, but the crucial paragraph proving Lord Goldsmith had performed a U-turn was blacked out by the Government, only to be revealed later the same day in a leak to Channel 4 News.

Why was the paragraph blacked out?

Jack Straw, the Foreign Secretary, said the key passage was removed by officials because it breached the blanket ban on revealing the legal advice given to Government. However, the decision to remove the passage sparked fresh allegations of a cover-up. Critics of the decision to go to war have long demanded to see the Attorney General's full advice on the legality of the action, because they believe the invasion breached international law and suspect that Lord Goldsmith may have been subject to political pressure to change his mind.

How did Lord Goldsmith change his mind?

Ms Wilmshurst's letter confirms that Lord Goldsmith originally agreed with Foreign Office lawyers that it would be illegal to invade Iraq without securing a fresh UN Security Council resolution specifically authorising the war. However, he eventually changed his mind, arguing that the Government did not need a second resolution in a ruling made public just three days before the war began in March 2003. That opinion has been the subject of fierce debate ever since.

So what legal advice did he produce?

On 17 March 2003, the Government published a one-page summary of Lord Goldsmith's advice to the Cabinet.

In it, he argued that military action was justified under international law because Saddam Hussein had breached UN Security Council resolutions. It emerged two weeks ago that he did not provide a more extensive formal opinion.

Ten days earlier, Lord Goldsmith had provided a larger document for Tony Blair, which argued that the war might be illegal and it might be safer to secure a fresh UN resolution explicitly authorising war before invading Iraq. This document has never been released.

The Attorney General has always denied being "leant on", but it is known that he only ruled the war lawful after asking for an unequivocal statement from the Prime Minister that Saddam had breached Security Council resolutions.

What would have happened if the war had not been declared legal?

Mr Blair may have lost the crucial Commons vote that authorised military action if MPs had not been reassured that the action was legal. Such a defeat would have ruled out the possibility of British troops joining the US-led invasion.

Senior military officers also needed legal cover to ensure that they would not be prosecuted by the international courts. General Sir Mike Jackson, the chief of the defence staff, was quoted as saying: "I spent a good deal of time recently in the Balkans making sure [Slobodan] Milosevic was put behind bars. I have no intention of ending up in the next cell to him in the Hague."

What would happen if the war was declared illegal now?

In theory Mr Blair could be indicted to appear before the international courts. In practice, such a development would be inconceivable. But politically such a verdict would be a severe blow to the Prime Minister's credibility.

Does it matter now whether the war was legal at the time?

Yes. Britain went to war arguing that the invasion was necessary to maintain international law and stop dictators flouting the United Nations. On the world stage, critics argue, it will be difficult for Britain to lay down the law with rogue states in the future if we flouted the same laws over Iraq.

Domestically, the latest developments ensure that the row over Iraq is still in the headlines at the start of the general election campaign and questions over the Government's handling of the war are fresh in voters' minds.

Where does this leave Tony Blair?

The allegation that Mr Blair "leant on" the Attorney General is very serious and is unlikely to be settled by this latest row.

The Prime Minister is left bruised, once again, over the war and facing fresh questions about trust in the Government on the eve of an election campaign when voters can have deliver their own verdict.