"but if a police officer completes all his training correctly and tries his hardest to make the right decision in that pivotal moment, but makes a mistake and shoots when he shouldn't, then he's sentenced to life in prison if he is held to the same standard as a civilian"

But that's the problem! The civilian shouldn't be going to jail, either, should they?

That is, I don't think the standard for prosecution for killing someone should be different for civilians and police.

Some would fix the problem by giving the police special immunity; I'd fix it by changing self defence laws for everyone.

Or perhaps, to put it another way, under what situation could you imagine yourself as a juror convicting a civilian of murder, but acquitting a police officer who acted identically?