Johann Hari: Jean Charles was a victim of the Tube bombers

To treat the police as murderers when they get the calculation wrong will lead to more dead

This morning, the Crown Prosecution Service will almost certainly announce that no individual police officers are going to be prosecuted for the shooting of Jean Charles De Menezes in a London Tube station - and a dam of rage is going to burst on to them. They will be accused of a whitewash and worse.

It is tempting to enter into this intoxicating anger. It would be easy to feast on our familiar emotional foodstuffs - that the police are racist and this was a uniformed lynching. There are many times when the police deserve our contempt: more than 700 black men have died in police custody in the past 30 years, and no police officer has ever been jailed for it. But is it right to direct this anger this time towards the police?

If you look at the choices confronted by the police that day, layer by layer, the anger turns to something more like understanding. A fortnight after 7/7, a day after 21/7, the police officers on the ground trailing Jean Charles were told they were following one of these attempted suicide-murderers as he prepared to try again. Their decision was not - as yours and mine would be - to run away screaming. It was to stay as close to him as possible, risking their own lives in order to save ours. They appeared to have a simple choice: keep their own hands clean, do nothing and see dozens die - or kill one person. In their minds, they chose to save life. Are these villains - or heroes?

Ah, but what about the senior officers who gave these officers on the ground the false certainty that Jean Charles was a jihadi? Shouldn't they be prosecuted? They certainly failed as they scrambled through a fog for information, knowing that four men were on our streets and eager to kill. One undercover team tried to get warnings through that Jean Charles was innocent, but their caution got lost in the sea of data cascading into Scotland Yard in that rushed 24 hours. A specialist firearms unit that could have arrested Mr Menezes was deployed five hours too late as the Yard's manpower was deployed in a (successful) attempt to track the attempted killers to Italy.

These are systemic failures rather than individual ones. The police had to make complex risk calculations, and one went horribly wrong. As so often, Ken Livingstone - a man who has been an consistent critic of police racism throughout his career, long before it became fashionable - put it best. He said: "They had to weigh up the potential loss of many lives against a decision to shoot to protect. They chose to protect. In a situation created by the terrorists, where hundreds of decisions, some with life and death consequences, are being made every hour, it is impossible that no mistakes be made."

This shouldn't be seen merely as a raking over of the past. Some day soon, another gang of jihadis will come to London and try to kill lots of us. If the CPS prosecuted individual officers today, they would ensure that when the next 7/7 comes, police officers would be reluctant to try to stop the suicide-murderers. The calculus of risk would become skewed in favour of police inaction - which would inevitably make successful jihadi action more likely.

There is, however, a real police scandal surrounding Mr Menezes. After Jean Charles was killed, he was smeared by sections of Scotland Yard, hinting darkly that he was a drug dealer. You remember the rumours - he didn't stop when he was called, he leaped over the tube barriers and ran, and on and on. All lies. The same happened with the young Muslim man who was shot last month in Forest Gate. He was accused of being an al-Qa'ida sympathiser when he was nothing of the sort, and even of being shot by his own brother. This is an area where police behaviour has indeed been obscene. Once it becomes clear they have made a mistake, there should be an immediate apology and lashings of compensation. Sir Ian Blair should - as a matter of urgency - track down the leakers who smeared the dead and sack them, as an example for the future.

But now Britain has to live (and die) with suicide-murderers on our streets, we have to learn to live with terrible risk-calculations that will sometimes backfire. The police are not omniscient. They will always be acting on partial, patchy information. With some criminals, you can wait until you are certain before you move in. With suicide-murderers, waiting for certainty means waiting for a carriage full of corpses. To treat the police as murderers when they get the calculation wrong is not just false - it will lead to more dead Londoners like Jean Charles in the long term.

And as the CPS reports today, remember - it was not the police who chose to put us in this position. As Ken said sadly: "Jean Charles De Menezes was as much a victim of the terrorists as those who died on 7th July. He must be mourned for what he was - a Londoner who we were proud to have in our midst and for whom we cannot adequately express our sorrow that, together with more than 50 other Londoners, we could not protect."

j.hari@independent.co.uk