a tough call to make.
2 weeks after the event described below it has been established that the man shot was not a suspected terrorist. He was a Brazilian man who had no terrorist connections.
Although details are still cloudy it appears that he came out of some flats being watched by the police, wearing a rucksack and walked into stockwell tube station. When he was approached by the police he ran into the station and down to the platform and onto a train at which point he was shot. It remains unclear as to why he ran when challenged by the police.
What worries me about the quote in the post below is that it sounds like an execution, and some people are likely to call the for police involved to be charged.
There are many victims from this event and apart from the obvious ones, don't forget about the people on the train, who saw a man shot 7 times in the head right in front of them. They will never forget this.
The policeman and his family will be deeply affected by this and should also be remembered.
Now let's look at the event and the policeman's choices,

1. a man, of foreign appearance, leaves a building thought to house terrorists
2. he enters a tube station on the London underground where there have been recent bombings.
3. when challenged by the police he runs towards the train.
4. The police give chase and when the suspect trips as he enters a train the policeman has to make the call. All the questions below have one thing in common, the policeman with the gun doesn't know the answer to any of them.

• why did he run?
• is this man carrying a bomb which he is about to detonate? If so I have to shoot him dead.
• if he doesn't have a bomb and I shoot him it will be a terrible mistake.
• if he does have a bomb and I don't shoot him, lots of people, including myself could die.

The risk that he was a bomber with the will to blow himself and many others was to great. The policeman made the right decision.

I have deliberately avoided the term "an innocent man" as he must have had a very good reason for running.

The Brazilian man's family are obviously deeply upset at the tragic loss of their son but I can't help viewing their apparent intentions to sue the police cynically.

There is going to be a full investigation and if the police followed their procedures correctly and the correct warnings were shouted then it was a tragic mistake, if the police procedures were not followed then they need to make damn sure this doesn't happen again, it doesn't mean the decision to shoot was wrong.