Unfortunately aiming to shoot somebody in the leg or the hand to disarm them is just TV fiction. There are very strict guidelines about when police can use their firearms: essentially the only time they can do so is when they believe there is an immediate threat to the lifes of themselves, police colleagues or members of the general public. If there is not this risk they are not allowed to shoot. If the risk is so severe that that the lives of innocent people are threatened the rules of engagement say that you must guarantee that the attacker is stopped. This means in most circumstances you fire at their torso or their head, which in most circumstances unfortunately means a lethal shooting. In the current circumstances the police guidelines have changed slightly to take account of the possibility that a suicide bomber will could be wearing a suicide vest packed with explosives - therefore police firearms officers have been instructed to shoot at the head if at all possible.
While the loss of an innocent life at Stockweel station is a tragedy for all concerned, I'm not sure the police could have done anything differently. There will be an independent inquiry to see what went wrong, but my guess is the police believed they were dealing with a suicide bomber who was making a desperate attempt to get onto a train to kill and maim innocent people. If I or my loved ones had been on that train I would want the police to make absolutely certain that they had stopped the attacker before he could detonate his bomb - unfortunately the only way to do this is by killing him. A shot to the legs or arms would have easily allowed a suicide bomber to press the trigger on his payload, which is a situation I'm sure we all would like to avoid if at all possible.
As Ken Livingstone said earlier today, the innocent Brazilian man who was killed at Stockwell was yet another victim of the bombers that have been tragetiing London in the last couple of weeks.
Regards
Rob
