The prime minister's office has released the confidential memo from Attorney General Peter Goldsmith after large portions of it were leaked to the news media.
The document was given to Mr. Blair on March 7, 2003, just 13 days before the Iraq war began. In the 13-page document, Mr. Goldsmith laid out the legal arguments for and against the war. He concluded that it would be best if the U.N. Security Council approved the invasion with a new resolution, something that never happened. And he warned that war opponents could bring legal action against British troops and government officials. However, in a second opinion issued 10 days later, Mr. Goldsmith told parliament the invasion would be legal under existing U.N. resolutions, and the statement reflected none of the earlier doubts.
Lawmakers then voted to approve Britain entering the war. With just a week to go before a general election, Mr. Blair's political opponents have latched on to the controversy to attack the prime minister's credibility and trustworthiness. The leader of the Conservative Party, Michael Howard, accuses Mr. Blair of deception to get Britain to join the United States in the Iraq war.
"If you can't trust Mr. Blair on the decision to take the country to war, the most important decision a prime minister can take, how can you trust Mr. Blair on anything else, ever again?" Mr. Howard said.
Prime Minister Blair denies that he lied, and says it will be up to the voters to decide if he was right or wrong to go after Iraq's Saddam Hussein.
"Understand, it was a decision this leader had to take for this country. I took that decision. The people are the boss in this election," he said. "They're going to have to make up their minds about it, and about my character and integrity. And that is in the end what it's all about."
The leader of Britain's third party, Charles Kennedy of the anti-war Liberal Democrats, accuses Mr. Howard's Conservatives of being two-faced, since they supported the Iraq invasion but now attack the prime minister over it.
"The role of the Conservative Party over these past two years in all of this has, quite frankly, been utterly pathetic, and it has got worse over the past two weeks in the course of this election campaign," he said.
Political commentators say the legal advice Mr. Blair got may go over the heads of voters, but the prime minister's integrity has become a campaign issue.
"I don't think this is going to sway another vote, but certainly the issue of Tony Blair's credibility, his honesty, his character, that is still looming very large in this campaign," said Ben Crookes, the national editor of the Financial Times newspaper.
Opinion polls continue to give Mr. Blair's Labor Party a comfortable lead over the Conservatives in the final days of the campaign for the May 5 election, with no sign yet that Iraq is having a significant impact.