I understand that this can be settled within contract jurisdictions, but how should one act in general? For example, if I see someone drawing a weapon in a public place, can I shoot first before they have harmed anyone?

Han Solo

I understand your desire to remove the responsibility for choosing the best course of action in an extreme situation. Unfortunately, it doesn’t work that way.

You see someone drawing a weapon in a public place. You can also draw a weapon and shoot first, or you can choose not to. You don’t know which decision will be correct because you do not have full information about the situation. There are real-life examples where a person drew a weapon to defend themselves from an attack, but bystanders decided that he was the attacker and shot him. What if that person is drawing a weapon to protect themselves from someone outside your field of vision?

Therefore, a safer practice is considered to be shouting the sacramental “Stop, or I’ll shoot!” before shooting anyone—this is done primarily to inform witnesses that you did not start the attack and that you are hoping for a peaceful resolution to the conflict. By the way, this is taught in firearm safety courses, so I’m not reinventing the wheel here.

Yes, any delay before firing carries the risk that you will not be the first to shoot. But no one in that specific situation will decide better than you which risk is preferable: shooting without warning and answering for having attacked, or giving a warning and taking a bullet.