Appearing before Sir Anthony Clarke, the Master of the Rolls, and two other senior judges, Rabinder Singh, QC, said that the mothers of soldiers killed in Iraq were entitled to know why, against so much advice to the contrary, the Government had come to the view that the invasion was lawful.

The mothers of Fusilier Gordon Gentle and Trooper David Clarke, both of whom died at the age of 19 serving in Iraq, were seeking a judicial review of the Government’s refusal to agree to an independent investigation into the circumstances leading up to the invasion of Iraq on March 20, 2003.

The Master of the Rolls, who is the head of the criminal justice system, along with Sir Igor Judge, the President of the High Court Queen’s Bench Division, and Lord Justice Dyson agreed to hear the full application themselves because it raised “questions of considerable general importance”.

The application is being opposed by leading QCs acting for the Prime Minister, the Defence Secretary and the Attorney-General. The Government’s case is that the issues at stake are a matter of political controversy for which it is answerable to Parliament and not to the courts.

In his opening statement, Mr Singh, acting for Rose Gentle and Beverley Clarke, said: “More than 3½ years after the invasion, a question mark hangs over its legality, and public concern continues unabated. In circumstances where not only many professors of international law and not only the former deputy legal adviser at the Foreign and Commonwealth Office were of the view that the invasion of Iraq would be unlawful, but the Secretary-General of the UN himself has publicly said that the invasion was illegal, the claimants can be forgiven for wondering how it was that the UK Government came to be advised that the opposite was the true legal position.” Mr Singh queried the whole legal process that led to Lord Goldsmith, QC, the Attorney-General, providing a brief but “unequivocal assurance” on March 17, 2003, that an invasion would be lawful — based on past UN Security Council resolutions relating to the 1991 Gulf War and subsequent resolutions linked to Iraq’s obligation to eliminate its weapons of mass destruction.

“Three days later the invasion began and just five days after that, one of the deceased in this case, David Clarke was killed,” Mr Singh said. It was reasonable to argue, he said, that there was a “causal link between the assurance given by the Attorney General and the deaths in question”. He added: “The two claimants come to court with reluctance. They are proud of their sons . . . who died with honour serving their country . . . but [they] are grieving parents in whose minds there are real questions about the legality of the invasion, the process which led up to that invasion and, in particular, the process by which the Attorney-General came to give an unequivocal statement on March 17.” Ten days earlier, Lord Goldsmith had produced 13 pages of equivocal advice including a preference for a second UN Security Council resolution authorising the use of force, which was never forthcoming.

Mr Singh told the judges that the late Lord Alexander of Weedon, former chairman of the Bar Council, described the legal justification as “risible”.

The hearing continues today.

Times Recommends

• City law firms prepare for painful year ahead
• Welcome to 2009: the year of the regulator
• Thacher Proffitt is latest US legal casualty