NRS 200.200: Killing in self-defense.

If a person kills another in self-defense, it must appear that:

1. The danger was so urgent and pressing that, in order to save the person’s own life, or to prevent the person from receiving great bodily harm, the killing of the other was absolutely necessary; and

2. The person killed was the assailant, or that the slayer had really, and in good faith, endeavored to decline any further struggle before the mortal blow was given.