The Jury, ITV1

Apart from voting, there is only one duty the United Kingdom asks of its residents: if, or less likely when, it comes, to answer the summons to sit and listen to evidence in a criminal court and, with 11 other randomly selected individuals, reach a collective decision about the guilt or innocence of the accused. Trial by jury is rightly held to be one of the more unimpeachable achievements of civilised society.

The jurors being emblematically the nice guys in this national success story, they are also the colourless guys. Which is why legal dramas – and there have been perhaps a dozen of them even this year – tend to leave the 12 good men and true in their two rows of six and concentrate on the leading roles of the courtroom: the barristers, the judge, the defendant, the victim. The Jury, m’lud, gives the jury its day in court.

Five nights in fact, over which it will spool out this week (it's the scheduling style of the moment: last week Top Boy was in and out in four days). The Jury entered the courtroom the way jurors do: through the relevant pass door, all eyes upon them. And it asks the question: who actually are these people whom we trust to deliver a safe verdict? This being ITV1, there’s a disproportionate ratio, for one, of good-lookers to regular munters. And then there’s the baggage they bring with them, evenly fanning out across the luggage carousel of life. That's the useful thing about juries: they allow dramatists to thrust together characters who have nothing in common. It's a bit like Christmas with wigs on.

For the defence Julie Walters is all fag ash and testosterone, while Roger Allam is prosecuting in pinstripes and RP

There’s a middle-aged man who lives with his old mum (Steven Mackintosh), a young Asian boy with some form of psychiatric condition (Aqib Khan), a neglected foreign millionaire housewife (Branka Katić), a token old codger (Ronald Pickup), a Muslim asylum seeker (Ivanno Jeremiah), a teacher (Jodhi May) who’s pregnant after an affair with a pupil. You get the picture: every juror brings a perspective into the court room which may have a bearing on their interpretation of the evidence.

And then there are the jurors who’ve been shipped in from central plotting, who in any regular vetting procedure would be weeded out before they put their hand on a holy book: a personal assistant (Natalie Press) who is pretending to be her busy posh boss (Sarah Alexander); a woman (Jo Hartley) who seems to have enjoyed a blind date with the defendant (John Lynch), himself in the dock for murdering four women on blind dates. One of the jurors is apparently being stalked by Lisa Dillon.

Where the jury have been sucked into a drama with a furrowed brow, the two barristers don their full fig like a couple of chummy rivals enjoying a workout at the fencing club. For the defence Julie Walters (pictured right) is all fag ash and testosterone, while Roger Allam – as per - is prosecuting in pinstripes and RP. It’s as if they’re in another drama, which, as long-term inmates of the courtroom and its arcane rituals, to be strictly accurate they are.

The Jury returns after one of the longer gaps between a first and second series in scheduling history. Peter Morgan first essayed something like this back in 2002. A year later came The Deal and he’s very largely concentrated on stories about characters from history near and far: not only Tony Blair but various monarchs from Henry VIII (twice) to Elizabeth II, not forgetting those eccentric cockatoos Brian Clough, Lord Longford and David Frost. After the task of sticking more or less to the truth and nothing but the (conveniently shaped dramatic) truth for a decade, he went for outright fantasy with Clint Eastwood’s Ouija-board saga Hereafter, and now here’s this. Astutely scheduled to hold on to Downton’s loyal fanbase, the task of The Jury is clear: to tell 12 good stories and true while also following the protocol of the court, all in five 45-minute episodes. It’s reasonable to doubt whether Morgan will pull it off, but so far he's making a good case.

• The Jury continues on ITV1 at 9pm until 11 November