To the best of my and any other commentator's knowledge, no member of the police force has ever been prosecuted for causing death, other than by reckless driving.

With all possible respect for the integrity of the police in general, it beggars belief that there has never, ever, in any case, been enough evidence even to bring a prosecution.

There is a term "moral hazard" which was much used with regard to the bank bailouts: meaning that if people know that they will never have to face the consequences of their actions, then no matter how good they are in general, some will be corrupted by that immunity.