I don't think we've figured out a good way to prevent this sort of thing while also making is possible to be able to fire the gun quickly when needed. The easy

I don't think we've figured out a good way to prevent this sort of thing while also making is possible to be able to fire the gun quickly when needed. The easy answer is "more training," but I suspect it has a lot to do with the fact that police in many places don't find themselves in dangerous situations that often and training only goes so far.