All this resonates with a macho and conservative subculture within the force, and there is no doubt that some policemen have spread leaks against Blair. He has made his own position more difficult by his overconfidence and one dreadful stroke of bad luck: Interviewed on the radio on July 7, the day of the London bombings, he said that British anti-terrorist policing was the envy of the world. Within three hours of his comments, the first round of bombs had gone off and killed 53 people.

He has been attacked from the left for allowing the officers who actually shot de Menezes to go on vacation immediately after the incident. But it looks as if the government has decided to back him, partly for the reasons that the Daily Mail is trying to destroy him. He is committed to reforming the police and to making them acceptable to the communities from which they must draw their informants. These reforms, along with controlling the armed police squads, are absolutely essential for a proper anti-terrorist campaign. (Blair estimates that about a fifth of his men are opposed to his reforms.)

Most crimes are not solved, as they are in many novels, by detecting criminals from the evidence they leave. On the contrary, the police know pretty well who the serious criminals are on their patch. Their job is to find evidence that will tie known criminals to particular crimes, normally by using intelligence. This is why police need consent, or at least legitimacy, from the communities they police. If no one will talk to them, no crimes will get solved and no criminals convicted.

But it's not just a matter of the police being trusted. The police must also be feared as more powerful than criminals; otherwise their guarantees of safety to witnesses can't be believed. But fear on its own won't do, which is what right-wing critics never understand. Nor do some policemen.

There have been worrying signs for some time that the members of the London police's elite firearms branch believe they should never be punished for shooting someone they suspect to be a terrorist. Last autumn, over a hundred of them went on unofficial strike after two of their colleagues were charged with murder for shooting in the street Harry Stanley, a Scottish carpenter who had been carrying a chair leg in a plastic bag. An anonymous caller had identified him as an Irishman carrying a shotgun.

There is no offense, in British law, of being drunk while in charge of a chair leg. Even if there were, the law is clear. The police are not allowed to shoot anyone unless they honestly and reasonably believe that it is the only way to save other lives (including their own). A dogged five-year campaign by Stanley's family, represented by the law firm of Cherie Blair, the prime minister's wife, led to a trial for murder of the two policemen who shot him. They were acquitted after persuading the jury that they had made an honest mistake. They have now been rearrested following a further investigation: Forensic evidence suggests they shot him from behind, so he couldn't have been brandishing the chair leg at them.

Meanwhile, an investigation has been launched into the leaks from the independent investigation into de Menezes' death. There is still controversy over the closed-circuit TV (CCTV) footage of the tube station, which would clear up a great deal of the story. Some police sources have claimed that the cameras were empty or malfunctioning. Others, in apparent leaks from the investigative team, have said this is nonsense. The whole story may not emerge until the investigation is complete, in about six months' time.

But whatever happens in the case of Jean Charles de Menezes, the policy of shooting without warning has been for the moment discredited and may be abandoned. It depends too much on intelligence's being infallible, and it never is. Even high technology doesn't seem to have helped here. Although the police had excellent CCTV images of the bombers they were hunting when they shot de Menezes, the officer whose job it was to identify suspects leaving the block of flats they were watching failed to confirm de Menezes' identity because he was, at the crucial moment, taking a leak.

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