Tony Blair doesn't cut it...

... and the QC is wearing denim. Raymond Whitaker on the staging of the Hutton inquiry

Close your eyes, and you could be back in Court 73 at London's Royal Courts of Justice. For those of us who spent the summer at the Hutton inquiry into the death of the weapons scientist, Dr David Kelly, the familiar phrases come back one by one: 45 minutes, weapons of mass destruction, sexed up, single source. And the endless acronyms: FAC, ISC, MoD, not to mention BBC and WMD...

Open your eyes, however, and you are in a rehearsal room at the Tricycle Theatre on Kilburn High Road, north London. James Dingemans, QC, senior counsel to the Hutton inquiry, has grown taller and thinner, and is dressed in denim rather than a funereal suit. But his words come straight from the court transcript, and when Justifying War, the Tricycle's dramatic re-enactment of the inquiry, opens on Thursday, the setting will match Court 73 in every possible detail, down to the myriad box files and plasma screens flashing up memos, emails and drafts of the Government's notorious dossier on Iraq's WMD.

For Hutton was far more than an inquest into Dr Kelly's death. It raised questions about standards of journalism at the BBC, the responsibilities of institutions to individuals, and whether secret intelligence was manipulated to take us to war with Iraq. Such issues were sure to attract the attention of the Tricycle and Nicolas Kent, its artistic director since 1984.

Set in a part of London with large Irish and Afro-Caribbean communities, the theatre has always been known for its topical and political approach, both to the new work it stages and the plays it revives. Its current production is John Bull's Other Island, a little-performed George Bernard Shaw work whose unexpected relevance has been commented on by the critics. But Kent has made the Tricycle best known for what he calls "tribunal theatre": distilling for the stage the testimony from some of the most important and troubling judicial hearings of recent times. Justifying War will be the fifth in the genre, and the most immediate. None of the events it covers happened much more than a year ago; Dr Kelly died only just over three months ago. "We thought we had an impossible time scale, with Lord Hutton originally due to report before we began our run, but now we will precede him," says Kent.

The sequence of tribunal plays began in 1994 with Half the Picture, the Scott inquiry into British arms sales to Iraq. After being regaled with the details for weeks by his friend and tennis partner, Richard Norton-Taylor, who was covering the hearings for The Guardian, Kent conceived the idea of recreating the inquiry in the theatre, and persuaded the journalist to edit down the evidence into a script. The production was televised, became the first play ever to be performed in the Houses of Parliament and, like all the rest, was broadcast on the BBC World Service.

The two have collaborated on all but one of the re-enactments that followed, from the Nuremberg war crimes trials to the Srebrenica massacre hearings at The Hague. Their last, The Colour of Justice, consisting of excerpts from the Stephen Lawrence inquiry, played in the West End and at the National Theatre, toured and was shown on BBC2. This hybrid of journalism and theatre has become so well-established that Kent had no trouble sitting in on the Bloody Sunday hearings in Northern Ireland, which he has yet to stage, or getting a court pass for the Hutton inquiry, where I assumed he was another reporter. Several of the cast also attended the hearings.

That the Tricycle would take on Hutton was never in doubt. "In 10 years we have progressed from selling arms to Iraq to trying to find them there," said the director. "It shows how Iraq has affected the thinking of this country - if black people defined themselves in terms of the conflict in South Africa and Irish people in terms of Northern Ireland, it seems Britain has defined itself against Iraq."

One problem with the latest inquiry is that instead of a single narrative there are at least three. The war in Iraq was followed by a battle between Downing Street and the BBC when the broadcaster questioned the Government's evidence - the title, Justifying War, is meant to refer to both conflicts. Then there is the treatment of Dr Kelly after he was exposed as the source for the BBC journalist Andrew Gilligan, who reported that the weapons dossier had been "sexed up".

Getting all this on stage in two hours has required some savage winnowing down. "We chose the characters to illuminate the arguments," said Kent, which meant Tony Blair, for one, did not make the cut. Nor did John Scarlett, one of Britain's most senior intelligence officials, who wrote the dossier. But we have the slipperiness of Geoff Hoon, the Defence Secretary, the thuggery of Alastair Campbell, the Prime Minister's departed aide, and the discomfort of Gilligan, his adversary. The main revelations are there, such as the moment when a retired intelligence analyst told the inquiry that he and his colleagues had thought the dossier was "over-egged", another phrase which gained immediate currency. There is even room for a comic turn in the unselfconscious windbaggery of Andrew MacKinlay MP, who informed Lord Hutton: "I'm like a sprung coil, my Lord." This time I was free to laugh out loud.

The only tampering with the sequence of witnesses is to give Janice Kelly, the scientist's widow, the final word. She did not appear in court, but testified over a voice link, an arrangement to which the production remains faithful. Her disembodied sadness and anger remind us of the human dimension of what Kent calls "almost a national emergency", and prove that there need be no lack of drama in these reconstructions. (Though it is ironic, given the Tricycle's anti-establishment credentials, that "tribunal theatre" requires a disproportionate number of middle-aged white male actors.)

Lord Hutton decided to ban television cameras from his courtroom (apart from the opening and closing statements), a rare boon for newspaper journalists accustomed to being shoved aside by the demands of TV. One might expect Kent to feel similar gratitude for such untrodden territory, but he disagrees.

"It seems extraordinary in the 21st century that the inquiry was not being broadcast, especially when only 10 members of the public could get into the court each day," he said. "Even if simultaneous transmission was not allowed, the judge could have ordered certain parts excluded - if he felt it would cause distress to a witness, for example. Far from wanting to exclude the cameras, we hope to put ourselves out of business."

'Justifying War': Tricycle, London NW6 (020 7328 1000), previews from Thur, opens 4 Nov, to 29 Nov