Last Night's TV - See You in Court, BBC1; Silk, BBC1; Supersize vs Superskinny, Channel 4

A guilty pleasure on this evidence

All aficionados of courtroom drama will be familiar with Magic Evidence, the kind of case-winning clincher that typically arrives at the 11th hour, just as the jury members are doodling nooses on their notepads. There was a fine example in the concluding episode of Silk last night, when, after a bad start with a grieving widow ("You're not helping your client by sniping at a dead man's wife," hisses Clive), Martha is able to turn the tables with the fact that the fingertips on the golf club were on top of the dead man's blood. Aficionados of courtroom drama may then have groaned audibly when Martha's case was also bolstered by the hoary realisation that the fatal wound was incompatible with a right-handed assailant. She's not only supposed to be good, she's also supposed to really care about this defendant, so you'd think that might be the kind of detail she would have noticed before the trial commenced. Anyway, more of her later. The exciting thing is that last night also offered a real example of Magic Evidence, in See You in Court, a new series about our spavined legal system, which began by following Sheryl Gascoigne and Lembit Opik in two individual libel cases. Struggling to refute an accusation that she hadn't talked to her mother-in-law in eight years, Sheryl discovered footage of herself making a sympathetic phone call to Gazza's mum, after trailing through hours of raw footage from a fly-on-the-wall documentary. Gotcha, as they like to say in tabloid land.

Lembit Opik wasn't quite as successful in his attempt to seek redress for a pugnacious Rod Liddle column that had represented him as a somewhat comical figure, and the deserving recipient of the last election's most surprising defeat. A 7,000 majority had disappeared overnight and Lembit was absolutely convinced that it was the press that had done away with it. He'd persuaded a sympathetic lawyer called Charlotte to take his case on on a no-win, no-fee basis and it was her thankless task to find a barrister with an equally quixotic commitment to the hopeless cause. A quick flash of a newspaper picture of Lembit, dressed in a catsuit for a Celebrity Big Brother challenge, hinted at the problems his legal team were up against, and just in case that didn't do the trick the documentary-makers had included film of him setting off on his Segway from his London home. In the end, a barrister charitably saved him from himself by declining to take the case on, at which point Lembit fulminated about the inequities of the libel system, in which big money will always defeat the little man.

His case might have been lousy, but his larger point was sound, though rather more convincingly backed up by Sheryl's experience. Thoroughly monstered by the tabloids, she actually had to put her house up for sale in order to cover the legal deposit should her wealthy opponents actually fight all the way to the courtroom. And if it went to court, even if she won and had costs awarded to her she would have ended up seriously out of pocket. In a game of chicken with a big newspaper, most individuals blink first, so it was rather heartening that Sheryl eventually extracted an apology and damages in all her cases. Unfortunately, the newspapers were probably still ahead on the deal, since they may have made more from the lies than the correction eventually cost them. It looks as if future episodes will demonstrate the unfitness of our libel laws with cases in which the positions of complainant and defendant are reversed, and journalists and commentators find themselves bullied into silence by the same threat of ruination.

Silk has been steadily building an audience and it isn't hard to see why. It has good villains, in the shape of Clive, a lethally untrustworthy old Harrovian, and Gary Rush, a sinister low-life in the grip of an obsession with our heroine. It has good twists, such as the revelation that the father of Martha's child was actually Clive. And it has a pretty solid continuing storyline, as various members of the chambers plot against Billy, the clerk, who has been a little bit naughty, bribing the lists officer so that he can get the right lawyer on to the right case. What it doesn't really have is a terribly authentic sense of courtroom life, though last week's joke, explaining that the CPS stands for Couldn't Prosecute Satan, was clearly the product of direct contact with the process of law. When the final trumping bit of Magic Evidence is supplied, for example (in canonical style by a junior galloping down the street, wig akimbo), neither the opposing counsel nor the judge seem to even murmur about the dramatic interruption of procedure. But then drama will always trump procedure – in any guilty pleasure.

Supersize vs Superskinny is a faintly mystifying contribution to the obesity genre, in which an undereater is paired with an overeater and the two swap daily diets. Since neither are eating healthily, this seems foolish to say the least. In last night's episode, for instance, overweight Louise notionally went for 36 hours without eating anything except a bag of sweets, which doesn't really sound like the first step towards a healthy relationship with food. And when they feel the need for a really spectacular display of flab they go off to America for a freak-show insert. I ate the whole thing, but I felt like putting my finger down my throat afterwards.