Sometimes watching television requires real commitment. Anyone who caught all 23 episodes of Murder One (BBC2, Tuesday and Wednesday) will have devoted nearly a whole day of their lives to the enterprise. It is the equivalent of three good nights' sleep (eight, if you have a baby), four translatlantic flights and 80 bouts of average-length love- making. A show has to be very special to attract such loyal support, yet Steven Bochco, who produced the equally addictive (but multi-narrative) Hill Street Blues, LA Law and Thirtysomething, does it again and again. How is it done?

Well, first you create some great characters. In this case the central figure is bald, big-eared, gravel-voiced Ted Hoffman (Daniel Benzali) - Yoda as played by Orson Welles - the wise patriarch of a law firm full of youthful talent, adolescent angst, raw ambition and Calvin Klein underwear. His Team get together around the big wooden table, just like the all-American family, except substituting briefs and theories for turkey and trimmings, all trying to impress Teddy/Daddy - LA Law meets Thirtysomething. And they are, of course, all babes. In fact, in this show, almost everybody's a babe; even the judge is a babe.

The defendant certainly is. Neil Avedon (Jason Gedrick) - who shares Michael Jackson's chiselled features, but is a lot browner - is ridiculously beautiful, when absurdly handsome is the norm. That's how you know that he is supposed to be a famous star.

Best of all, though, is demonic Richard Cross (Stanley Tucci), welcome proof that, despite American Gothic, Twin Peaks and The X Files, not all American villains hang upside-down from rafters during the day, or can be summoned by the pentangle.

OK, we have the bodies, what about the words? We need wryness, we need wisdom, we need raw emotion, we need a little Grishamesque jargon to lend authenticity.

This is Chris Docknovich (absurd name), after the Team has lost the trial: "I blew it. I blew the trial," he laments, head in hands. No, says a delectable female colleague consolingly, "there were a million variables that went into this case, Chris". "You're right. But I just wish I wasn't one of them." Enter Ted for one of his paternal homilies. "Chris, you learn more from your defeats than you ever learn in victory." He leaves. Chris: "And that is why that man's name is on the door." A universe in three cliches.

Should Richard Cross, now in the final stages of Aids (stage four, apparently), take drugs to help him testify? Doctor? "While it will decrease the symptoms of dementia, it will greatly increase bone-marrow depression and cardiac necrosis." God! Will the judge allow Ted to present the tape of Jessica's murder? "For the moment, counsellor, I will take your motion for an evidentiary hearing under advisement." Wow!

And to get characters to do things that are (a) necessary to the plot and (b) completely alien to their personalities, what better than lashings of emotional blackmail? You owe it to me, you owe it to Ted, you owe it to Jessie, you owe it to them, you owe it to us, you owe it to the viewers.

Now we need a plot. Or rather, for 23 episodes we need 23 plots; for it is a cardinal rule of TV drama that each episode must contain a significant plot twist. When BBC1's epic Seaforth broke this rule a couple of years ago, it bombed. Murder One insured itself against such an eventuality by having four or five plots per programme, some of them very odd. They included the vengeful wife, the prodigal daughter, the demented villain, the lying doctor and many, many more. The necessarily daft tying-up of these disparate strands, shortly before Teddy's Agatha Christie-style Grand Revelation, led to prosecutor Miriam Grasso (Barbara Bosson, aka Mrs Steven Bochco) expostulating, "Don't tell me. It was the One-Armed Man." A nice piece of distancing, that.

Only two things remained. First, who really did it? Not an American, thank goodness. Unlike Oklahoma City and Centennial Park, this crime was carried out by a foreigner - Colombian drug baron Roberto Portalegre; a crim so cunning that he managed to get a parking ticket outside the murder flat at the precise time of the killing.

And we must tie up the emotional bit. So Mrs Teddy appears in the Hoffman penthouse office to tell her ex-husband that he's just great. "It was you, Ted. Your passion, your single-mindedness." She gives a wry, loving, tearful smile suggesting the possibility of reconciliation, under new terms.

The terms - presumably - include his giving up the law, for Hoffmann is not to appear in the follow-up. This has been interpreted as a capitulation to the ratings merchants who want a more sexy star, but I suspect the real reason is that we have gone as far with Teddy as we can go. Anyway, what will the new show be called? Murder Two? Murder One 2? Murder Too? Another Murder One? Whatever, it will have a great cast, fantastic production values, a memorable theme tune, a montage title sequence and a silly plot.

Some people believe that the current sequence of US hits like Murder One make our programmes seem pallid by comparison. For example, try and imagine an episode of Casualty in which Charlie Fairhead and a doctor from Holby General happen on a road crash and amputate the trapped leg of a Premier League soccer star with a power-saw; where another doctor takes out the wrong adrenal gland of a woman (secretly suffering from Munchausen's) who has been a lover of his; where a third doctor is about to give a transplant of foetal tissue to an old chum, the said tissue to be procured by aborting the man's wife. There would be an outcry. We'd ask whether Alan Yentob or someone hadn't gone mad. But such was indeed the plot of last week's Chicago Hope (BBC1, Friday). Once again we had a posse of fabulous-looking hunky docs, lubricious nurses, enough blood and diagnosis to satisfy an ardent operating-theatre buff, and a stupid story. But this was Chicago, runs the unspoken thought, and over there things are a little different.

In Britain we do it the other way around. We don't have the money, but we do have the realism. Take Out of the Blue (BBC1, Monday), the Northern rozzers drama that returned this week. It too has an ensemble of characters, none of whom is particularly interesting. There is no demon in human guise, or infallible paterfamilias, and only a smattering of babes.

Instead of the public buildings of Los Angeles, the skyscrapers and the beaches of California, Out of the Blue is set in one of those Northern towns the train stops in for two minutes too long, and in cop-shops full of flip-charts and Formica.

As with most British police series, much of the action takes place in blocks of Forties flats where the walkways and stairs have anticipated Richard Rogers, and are all on the outside. This allows the camera to catch policemen dashing up and down the steps, chasing baddies around the balconies, or - sometimes - to discover suicidal teenage offenders about to plunge to their deaths.

And Out of the Blue had three more things that any Yank series would have lacked. The first was puke; in this case it was orange and it landed on the table in an interrogation room. American shows don't do vomit.

The second was sex. Not soft-focus lip-grinding, but a scene straight out of The Singing Detective - an extended top-shot of rolling buttocks which graphically explained the origin of the term "rumpy-pumpy". There didn't seem to be much room for dissimulation, so all I can say is that I hope the actors are married.

The third was a story that was all too believable. It concerned teenage parents, members of a poor and ignorant underclass, whose baby had died of neglect. They had gone to the pub leaving "our Dale" ill in his cot, because they simply hadn't known what to do. "They won't put me away," said the mother, whose face we have all seen a dozen times in our cities, "because I'm pregnant." That never happens in LA.