It's not my place to make judgements about America. But I know that in this country, England, innocent people have been locked up in prison for much of their lives. And the main reason why has been that there have been police officers who have lied through their teeth, destroyed and withheld evidence, and forged confessions.

The Maguires were innocent. The Guildford Four and the Birmingham Six were innocent. And the list goes on. And it isn't just the well known cases - just for an example, my son's best friend at school was locked up for a month, at a crucial time of his education because he went on a demonstration, and was falsely accused of things he had not done, by a policeman on oath.

That doesn't mean that, in the words of the traditional saying "All coppers are bastards", because they aren't. But it is true that many otherwise decent police officers see it as acceptable to turn a blind eye sometimes to what colleagues get up to.

Civilian review boards are all very well - but the real thing that is needed is a change in the police culture, so that turning a blind eye was seen by decent police officers not as an honourable or at any rate acceptable thing to do, but as a shameful failure of duty, and as a betrayal of the police service.