Men in white coats with delusions of grandeur

I don't want you to get the impression that I'm becoming obsessed, but the BBC's "States of Mind" season is definitely having a strange effect on me. I suspect it might be a conspiracy. They're using the transmitters to get inside my mind. Today, for example, I had firmly resolved to take a break from insanity and relax with Elijah Moshinsky's Omnibus film about divas. But I reckoned without Minders (BBC2), the first of six documentaries about a south London mental-health team. I began watching in a faintly desultory spirit - just keeping an eye on things really, in case I returned to the season later in the week. But by the end, I was in need of tranquilising drugs.

Lorraine Heggessey's film followed the case of Philip Adoo , or John Baptist, as he prefers to be known. John, a young Ghanaian, is convinced he was born white and that his twin sister has been cannibalised. These are unorthodox convictions, it's true, but they are not actually dangerous in themselves. At the beginning of the film, John was looking after himself in a clean, well-cared-for flat, and though his finances were in some disorder, he wasn't annoying his neighbours or behaving in a violent or threatening way. He talked calmly about the frustrations of his life and, in his own skewed way, wasn't without hope: "I'm just praying I can get in touch with Auntie," he said, "...that's the Queen."

Despite all this, it had been decided to admit John for compulsory treatment under Section II of the Mental Health Act. Professor Tom Burns - the consultant John had no wish to consult - was convinced that "he needed treatment". It was at this point that events began to take a nightmarish turn. It's important to tread carefully here, of course, because television is expert at provoking facile indignation. After all, you were invited to make your own amateur diagnosis of John on the basis of a few minutes' film, and to set that against the professional opinion of those who had followed his case for months. John was lucid, even mentally nimble when fighting against enforced medication, which only increased your anger on his behalf. But perhaps that clarity of mind meant that he knew how to work the cameras to his own advantage.

In fact, such concerns proved immaterial. The before and after pictures were distressing - a calm, articulate man transformed by drugs into a quivering state of depression. But the words of the doctors alone would have told you that this was an injustice, the tyranny of the orthodox over the odd. Time and again you came up against the sort of looped logic that would drive anyone into a straitjacket. One benefit of the drug used, explained Professor Burns, is that "it develops a bit of retrograde amnesia, so often the patient doesn't remember the rather undignified tussle involved in giving him an injection".

Another doctor, speaking during one of the appeal tribunals, insisted that "it would be inappropriate to be judgmental about the severity or the nature of delusional ideas", apparently forgetting that exactly such a judgement was the only basis for medical treatment.

Nobody chose to explain which delusions are "unacceptable" or "inappropriate". Thousands of people in Britain believe flying saucers have visited earth, and many thousands more that an executed Galilean rose from the dead and will guarantee eternal life - but that isn't widely regarded as good reason to lock them up and pump them full of drugs. Professor Burns, serene and undoubting, will not, I think, comprehend this point. His faith is in the chemical cure, whatever the results look like. He knew he couldn't contradict the evidence of our eyes, so instead he left us with his cruellest piece of chop-logic. "I think he is sadder... and I think actually that's an improvement, because he is more of a whole person."