I've had a few arguments about this with people I respect. Here are my thoughts...
There are clearly two sides to this:
1) Yes, the police had no choice. After all, this guy was followed leaving a known terrorist tower block, he was wearing heavy clothes on a hot day, he was wearing a rucksack, and he ran further into a tube station after police told him they were armed and that he should stop.
2) He committed no crime, and he was innocent, yet was killed.
Aside from the simplicity of the justification of (2), how could things have been done differently?
Well, clearly, very few of us are qualified to comment. After all, the police in question are well trained, and ought to be the experts in their field. We by comparison have probably never even held a handgun, much less shot one with the specific aim of killing someone so completely that they have no nervous reflex.
However few of us have no opinion on this. Did the two policemen have a choice? In my opinion, the answer is "no". I think they probably followed the police defined protocol properly, and will be exonerated for what they have done. However, we are still left with a man who has committed no (capitol) crime. After all, any visa or tube ticket misdermeanors are far from capitol offences.
One major argument against Mr. Menezes is that he ran after being told to stop. I have to admit this is a hard one to argue against. However, the decision he made is not expected to be rational, and this is instictive. Instict is partly genetic, and partly cultural. This man was from Brazil, where the foreign Minister tells us, "many areas have a higher death rate than many war zones". Thus, Mr. Menezes saw a gun, and made a decision to run. This is a perfectly valid and acceptable choice in many countries around the world.
So we arrive at the argument "but running from the police is not normal behaviour in the UK". I also accept this is difficult to argue with. However, this argument is a product of our upbringing. We Brits believe that the police are virtuous, and that the innocent have nothing to fear. However I would argue this is naive, after all, we have a well publicised case of an innocent man being killed for "looking guilty". Note that he hasn't been improperly imprisoned, his life was ended, without trial, without hard evidence (no court would allow any of the available evidence as anything other than "circumstantial").
I have many issues with the Menezes case. However, it all boils down to the UK's general acceptance of what has happened. People seem to be accepting that the police made a difficult choice, and that it was "okay". I have issue with this because it suggests that the police can do what they want in "difficult circumstances" without needing to justify that to the public (whom, incidentally, employ them).
Once we stop questioning the "powers that be", and reduce our expectation of them from being excellent, then we allow them to create a Police State. After all, if we're risking our lives by ignoring their requests to "stop", what next? I mean, if a policeman says "armed police, take off your clothes", do you do it? Where do you draw the line? Bear in mind that they can issue these requests with no evidence against you, not even so much as a suspicion could have you doing anything any random policeman wants.
I can of course see my argument is extreme. However, Mr. Menezes didn't know he was a terror suspect, he had no way to know he lived in a terrorist suspect tower block (along with a hundred other people), and carrying a rucksack doesn't constitute a crime.Thus, Mr. Menezes made a reasonable, if rash, choice, which unfortunately ended his life.
What happens if you, or someone close to you, makes a bad decision? Will you feel the same about the police policy then? Probably not. Of course, if the police don't shoot someone that subsequently kills a dozen people on a tube, then we'll all feel differently again.
The trouble is, this is prone to emmotional arguments. If the police miss someone and people die, then of course, we'll all advocate stronger police powers. My argument is not that this reaction is wholly inappropriate, but instead that no matter what happens, the police are accountable to us in every detail. If they screw up, difficult circumstances or none, they have to be able to justify their position to us (the more difficult the circumstances, the more excrutiating the detail should be).
In truth, I don't think the Met are mssing this at all. I mean, they have handled the situation impeccably well. The Home Office have not been helpful, but this fact has been well spotted by Nick Hardwick, the independent investigator. I do think that the Met will "fix" the "problem" as well as anyone could ever do. That doesn't make me stop wanting to put them under pressure to do so though.