Last night's viewing - The Jury, ITV1; The Growing Pains of a Teenage Genius, BBC3

Julie Walters overacts wildly in Peter Morgan's latest television drama. She's hammy, melodramatic, and goes so far over the top at times that it's a wonder she doesn't black out from oxygen deprivation. Fortunately, there's an explanation. She's wearing a horsehair wig at the time of the most grievous offences, playing a defence barrister in The Jury.

And, as anybody who's ever watched a courtroom drama should know, hamminess is as integral to adversarial law as precedents and cross-examination. It's one of the reasons that courtroom drama works so well, because the setting itself is framed for unexpected reversals and histrionic confrontations. Add a jury to the mix – with its random biopsy slice of the national character – and you have the perfect armature for a strip-scheduled series that might just blow a hole in the opposition's week.

Morgan did the first series of The Jury in 2002 and, though it was well reviewed and popular, ITV didn't ask him for a second one quite quickly enough. He's spent the intervening years whiling away his time with projects such as The Queen and Frost/Nixon and returns not as a jobbing television dramatist but as an award-winning screenwriter, a fact that inevitably raises expectations a little. And though it's a little too early too say whether The Jury will successfully tug audiences all the way through to Friday, its first episode had as many baited hooks on it as a mackerel line. The case in question is a retrial – the conviction of a serial killer having been overturned by the Court of Appeal. So now Alan Lane is back in court – sporting a crucifix and the sorrowful demeanour of a legal martyr – to have a fresh jury decide whether he killed three women he met on an online dating site.

As the jury selection letters were dropping through letterboxes, Morgan had a fictional justice secretary on the Today programme, ripping into the inefficiencies of trial by jury. Morgan, one takes it, doesn't share that view... but if he's seeking to defend the institution, he's going about it in a rather odd way, with a startling number of his jurors in some difficulties when it comes to a dispassionate analysis of the evidence. One of them is actually breaking the law, having been sent by her PR boss as a ringer because she's in the middle of a big business deal. Another is a hunched young Asian boy whose parents keep talking anxiously about his "condition", while Jodhi May, a young teacher, is taking refuge from a classroom romance that could actually put her on a sex offenders register if it's discovered. There's also a male juror whose main preoccupation seems to be finding the nearest tanning parlour, a Sudanese refugee killing time while he waits for an American visa and a lonely trophy wife flirting with the idea of going online herself.

Morgan provides some nice tart exchanges for Walters and her legal opponent (Roger Allam) when they're outside the court, but I'm not quite as sure about the legal speeches, which – even allowing for the thwarted thespianism of barristers – seem more likely to make jurors giggle than change their minds. But with a tantalising stack of questions that need answering (guilty or not guilty? Who's the weird woman who appears to be stalking one of the jurors? What's with the tanning?), forensic plausibility may matter less than sheer curiosity. It's started well, and it would be premature to declare a mistrial at this stage.

The Growing Pains of a Teenage Genius was about Cameron, aged 13, whose maths skills are considerable but isn't too confident with the human stuff. He has Asperger's and, as he put it, has "the social ability of a talking potato". Quite a charming potato, though, and, by the end of Barnaby Coughlin's lovely film, also a potato who appeared to have a girlfriend in the offing. She's very, very keen on Doctor Who, but I think Cameron sees that as a plus.