Britain's decision to go to war in 2003 was hotly contested at the time. Nearly a million people demonstrated against it in the streets of London in the weeks leading up to the invasion.

Two British cabinet ministers, Clare Short and Robin Cook, resigned over the decision to go to war. They said then Prime Minister Tony Blair had exaggerated the threat from Iraqi leader Saddam Hussein.

On Tuesday, a five-member panel made up of two historians, a former ambassador to Russia and two senior civil servants, began looking into the events surrounding the decision that took Britain to war, dating from the summer of 2001 to July 2009.

Up to the task?

The lead up to the inquiry has also been dogged by controversy.

Prime Minister Gordon Brown wanted it to be conducted in private. The head of the inquiry, Sir John Chilcot, ruled that it would be public and televised, to make it accessible to as many people as possible. If a witness has evidence that might compromise Britain's security or other vital interests, then the evidence will be heard in private.

Analysts, like historian and author Robert Fox, have been critical of the panel's makeup, which includes no legal or military experts. Fox says that could mean that crucial evidence could be misunderstood or missed entirely, as there is no one on the panel with the expertise to question a witness more closely. The panel itself was chosen by the Brown, calling into question its independence.

Responding to the criticism on British radio, Chilcot dismissed concerns that his report would be a "whitewash," and promised a "full and insightful" account of the witness testimony and all other evidence collected by the inquiry.

While the investigation has no legal powers of enforcement, Chilcot said he was confident that witnesses would be truthful, because making misleading statements at a public inquiry would likely be damaging to a witness' career.

Positive signs

Liberal Democrat politician Sir Menzies Campbell told Deutsche Welle he was encouraged that so far the government seemed to be forthcoming with thousands of relevant documents.

"The inquiry says it has had access to all the private and confidential papers that surround this issue, so it does seem that the inquiry is going to have access to everything that is necessary upon which to reach a valid informed conclusion," said Campbell.

The first subjects that the inquiry will cover include UK policy toward Iraq in 2001, weapons of mass destruction, the trans-Atlantic relationship, developments in the United Nations and military planning. Early witnesses include senior politicians, military officials and diplomats. Tony Blair is expected to testify in early 2010.

The conflict in Iraq cost 179 British lives. Many family members of those killed met with members of the panel to discuss what they hoped the inquiry would achieve. Some have accused Tony Blair's government of misleading the public over the reasons for the war. Many plan to be present when Blair testifies. Chilcot said the meetings with family members helped him decide how the inquiry would be conducted.

The panel is not expected to report before the end of 2010, or possibly in 2011. Chilcot said he would do all that he could to avoid protracted proceedings.

Showdown with Blair

This will be the most in-depth and wide-ranging investigation into Britain's role in the war in Iraq. Blair's critics accuse him of blindly following then US President George W. Bush into battle. Some say Blair's role in Iraq divided Europe and was the main reason for his recent rejection for the post of European Union Council president.

Newspapers and politicians have called the decision to go to war in Iraq Britain's biggest foreign policy fiasco since the Suez Crisis of 1956. The Iraq war inquiry has no real precedent.

"The inquiry has said that it is not a court of law, that it's not to find people guilty, but at the same time, it has said that if there is fault and it believes there to have been fault, it will say so. So I think you may well find quite a lot of blame attaching to those who are directly concerned," Campbell said.

It is unclear whether Gordon Brown will be called to testify. He was chancellor of the Exchequer at the time. He must call an election by May 2010 and some analysts have said he timed the inquiry so that its results would not be published before the general election.

Author: Jennifer Glasse, London
Editor: Nancy Isenson