A live prisoner is much more valuable than a dead body. Even assuming that it's not yje wrong desd bidy, like Jean-Charles de Menezes, the Brazilian electrician shot seven times in the head while being held down in his seat on the London Tube.

And remember, in the case of jihadists, they want to be killed. Shoot-to-kill is doing them a favour, and they don't deserve being done a favour.