I think it should be the cops discretion if who they are fighting is using lethal force. If You are shooting at me with a 7.62 and all I have is an MX, then I should be able to load lethals. It only makes sense to match lethal force with lethal force. If I kill you though, you shouldnt lose your bounty and the cop should get no money for it.
Bounties should only be paid on living prisoners.
If I load lethals, I lose out on the option to capture and get the bounty. If I want the bounty, I have to risk using downing rounds and get to you to restrain you without getting killed myself.
Doing it this way dismisses all the issues regarding the grey areas of when using lethals or not should or shouldnt be approved. If youre robbing fed and shooting it out with cops, getting lethaled should be expected.