There could be few bolder political fantasies today than imagining Tony Blair being investigated by the International Criminal Court to see whether he could be indicted for aggression against Iraq. It could not happen.

Yet such a dream, cherished by hundreds of thousands, now springs to startling stage-life thanks to those remarkable makers of contemporary political theatre, director Nicolas Kent and Richard Norton-Taylor, security editor of The Guardian.

The Prime Minister himself is not one of the characters in this production, which considers how and with what legitimacy Tony Blair took Britain into the Iraq war. Even so, he looms over the action like a ghost noisily walking a haunted house.

In the courtroom process, Mr Blair's reputation - that long-lost prize of his - takes a familiar sort of battering as he is accused of manipulating intelligence and misrepresenting the Attorney General's advice on the legality of the war to Cabinet, Parliament and Britain.

The apparent discrepancy between the Attorney General's advice to the Prime Minister on 7 and 17 March comes to seem the crux of the matter.

William Hoyland's wonderfully patrician Sir Murray Stuart-Smith, former commissioner for the intelligence services, registers critical bemusement.

Diane Fletcher, who deftly catches the tone of former International Development Secretary Clare Short, gives an illuminating impression of what it was like to be in Cabinet on 17 March. Her worried queries about lack of discussion were met with Cabinet cries of "Oh, Clare, be quiet."

Despite the sensational nature of Called To Account, it lacks the smack of conflict that made earlier Norton-Taylor/Kent dramatisations of official inquiries, such as The Colour Of Justice and Bloody Sunday, so enthralling.

It was Kent's conceit on this occasion to imagine Mr Blair investigated by the International Court, with well-known barristers Philippe Sands and Julian Knowles speaking for the prosecution and defence respectively.

The testimony of real subjects from Parliament and the civil, diplomatic and security services, together with the odd journalist and diplomat, was recorded in London this January and Norton-Taylor then edited their evidence for Called To Account.

The legal tone is neither one-sided nor shrill, but always cool, clear and shocking in Kent's restrained production. A few fresh facts emerge, but nothing momentous.

The two lawyers never clash or clamour. They handle each of the witnesses with respectable kid gloves. So the atmosphere is more akin to a lecture hall than a courtroom.

For all its clarity, Called To Account could sometimes do with infusions of that absent theatrical commodity - passionate emotion. For these witnesses are, with the exception of Fletcher's illuminating Clare Short, trained to keep the human touch under wraps.

Thomas Wheatley, who often plays these Kent/Norton-Taylor dramatisations, makes an authoritative Sands. The focus of his questions relate to Mr Blair's real purpose in warring against Iraq: was it regime change or the elimination of those notorious weapons of mass destruction, details of which he may have, well, dramatised?

The prosecution lacks concrete evidence to make its case. What emerges, shockingly, is a sense of a messianic Blair riding in easy triumph over sheep- and Ostrich-like Cabinet ministers, towards a war that may make us a terrorist target for decades.