Bruce Anderson: The police were right to shoot, even if this time they got the wrong man

Anyone who behaves as Mr de Menezes did cannot have been keeping abreast of current affairs

Even so, Friday's shooting was also a further demonstration of the courage and professionalism of the police force. In the most dangerous of contexts, a man draws suspicion upon himself. Refusing to stop, he hares off into the Underground. The police pursue him, although they could be running towards their own deaths. They catch him and dispatch him in the manner designed to minimise the risk of his being able to explode a bomb.

If Mr de Menezes had been a terrorist, the policeman who shot him would now be in line for a gallantry medal. As there was no bomb, the police officer must face an inquiry while coping with his own feelings of guilt.

We can only hope that the inquiry is held as quickly as possible and ends with the policeman's exoneration, reinforced by assurances from senior officers that he not only did the right thing. He took the sole action compatible with his duty.

It is sad that Mr de Menezes was shot, but anyone who behaves in that way cannot have been keeping abreast of current affairs. His conduct invited the police to draw the conclusions which they did and to act as they did. He was the author of his own misfortune.

Those who run the Metropolitan Police will be able to come to that conclusion. Once they have done so, the policeman concerned will be entitled to return to duty, without a stain on his reputation. His senior officers will have been able to protect him. If only the same applied on the battlefields of Iraq.

Two years ago, Trooper Kevin Williams of the Royal Tank Regiment was manning a checkpoint. When ordered to stop, an Iraqi ran away. The trooper and a comrade pursued him. He led them into a house; it could have been an ambush. He then tried to grab the other soldier's rifle. Kevin Williams shot him. It was discovered that the cart which the dead man had been pulling contained weapons, and that he had terrorist links.

In any other army, it is probable that bullets would have been used for the initial pursuit, but Trooper Williams's actions were reviewed by senior officers, who decided that no offence had been committed.

That was not good enough for the lawyers back in Britain. They reopened the case, and decided that the trooper should be charged with murder. For two years, he had to live under the threat of a murder charge until it was at last dismissed for want of evidence.

The freedom of other soldiers whom their commanding officers believed to be innocent is now at risk because of the activities of lawyers: in some cases, shyster lawyers, delighted to take the opportunity to undermine the Government's policy in Iraq. But if we understand that policemen in London sometimes have to take instant life-and-death decisions in order to protect us, we should surely acknowledge that this is even truer of soldiers in Iraq.

Returning to London, it is tempting to form a benign conclusion about Thursday's events. For once, our enemies' powers fell short of their malice. Even though they had enough resources to co-ordinate their bombings, it appeared as if they had run out of suicide bombers and top-class bomb-makers. Their failures must have presented the police with large amounts of forensic material. It is to be hoped that this will make it easier to roll up the terrorist networks with which the bombers were connected.

But even if that proves to be so, it does not mean that we can roll up the map of Islamic terrorism. There are bound to be more attacks. Over the past few days, there has been a lot of silly criticism of the security services and of MI5 in particular. The implication has been that MI5 and its director general, Eliza Manningham-Buller, must have been negligent.

This is partly due to the contemporary blame culture; the obsessive assumption that if anything goes wrong, someone must be guilty. In the case of counter-terrorism, this is more than unusually erroneous. It grossly underestimates the scale of the potential threat and the difficulty of dealing with terrorists who have no interest in their own survival.

It has been alleged that MI5 might have disregarded warnings about specific individuals who were therefore allowed to enter this country. That ignores three points.

The first is the sheer number of warnings which the security services receive; these cover thousands of people. The second is the legal context. When this Government passed the Human Rights Act, it became much harder either to imprison undesirable foreigners or to deport them. As a result, our authorities can no longer take crucial decisions affecting our security. They have allowed themselves to be over-ruled by legal constraints of foreign origin.

Given all that, MI5 would hardly be popular with ministers if it recommended the arrest of everyone who might come under suspicion. Equally - the third point - there may be times when the security services do not want to arrest a suspicious individual at the border. They might prefer to let him in and then follow him to identify his contacts.

There is a further factor. We know about the terrorist attacks that succeed. We must not forget the ones that are aborted. Over the past couple of years, there have been several of those. In some cases, the malice was intercepted many miles from these shores, often with help from other nations, including France. Whatever one thinks of the French, their security services have been staunch allies.

There is no reason to doubt the efficiency of Britain's security services or to change intelligence policy. We should also be sceptical of the value of new laws. Sometimes this Government talks as if an additional law should be passed every time a crime is committed. Terrorism is already illegal. If new anti-terrorist laws were needed, one obvious point ought to be made; why was this not done long ago? The only desirable legal change is a repeal of the Human Rights Act, so that home secretaries regain the power to exclude undesirable aliens.

Law apart, there may be scope for technological improvements. In the clear vision of hindsight, one could wish that more had been done to accelerate research into the detection of explosives, so that those entering the Underground could be scrutinised automatically as they walked in at a normal pace. But as soon as science stops up one rat hole, the fanatics will find another. To defeat them, we will have to summon up our stoicism, and hope for good luck.