Even if the attacker was intent on killing you, how can you then jump to the conclusion that your only reasonable defence is to kill them first? You can't, because it isn't true (it isn't reasonable in the slightest).
I'll stick with Military Law, it's what I studied and enforced. Person A shoots at Person B. Defendant B shoots back at Person A, killing them.
Person A has utilised lethal force. The defense for Defendant B would be 'defence of life' = Righteous.
Obviously this is a [game], but it would appear for all intents and purposes that 'real life' analogies are used, and enforced. Therefore, aligning the C&P with [typical] rules of engagement would also be righteous.
The school of thought that says [crimes on/off] has any bearing on this is misplaced at best and farcical at worst. A crime is/has being/been committed. To assuage that school of thought one then has to make the fundamental leap that 'unless the crime is reported as it is happening, it is not a crime'. This is just stupid.
Report Crimes On/Off, is there to simply state whether I want the federales to help me or not.
I can assure you, in my time overseas, if I was shot at, I shot back, with intent to kill. There is no room for 'oh lets just wound them', or 'lets wait for the police' in situations where it's your life or theirs.
Sorry that's real life. All the armchair heroes can say what they like.