There have been cases in the US where homeowners shot cops dead who were in the process of unexpectedly raiding their home, because the homeowner had no idea they were cops and not home invasion robbers; and in some cases have been acquitted of murder charges by juries for this.

I'd personally like to see the laws protecting this strengthened, to make sure that cops aren't charging unannounced into peoples' homes and then charging the homeowner with murder when they react with reasonable gun violence in self-defense.