Many people assume that bad behaviour shown on television is copied in real life, an assumption often aggressively asserted as though it were a proven fact or, at least, so obvious as to be unchallengeable. Good evidence is, however, lacking. But the makers of programmes are not allowed to shelter behind that. They are urged repeatedly to take the matter very seriously. The broadcasting regulators and watchdogs certainly do. So does public opinion. More importantly, the unproven possibility of a causal connection disturbs any decent conscience.At the heart of the concern is the belief that only one death or serious injury caused by imitation is one too many and cannot be accepted.