I am curious about "rules for killing" in many philosophies/spiritual systems/religions(/1-law). It seems to me this is an unsolvable problem. Most "solutions" seem arbitrary/unclear/illogical.
I would like to answer at length but am extremely busy relocating. In short - killing someone without their consent violates the One Law. The-One-Law defines such as not a "Being".
To me, killing has a spectrum of shades of gray, in many "dimensions". There is the intention/mind of the killer, there is the mind of the victim, there is the "likeness" and so on.
Aside from physical aspects, the only other relevant issue is whether the victim consented. Feelings, emotions, benevolent intentions and other imaginary excuses are all irrelevant.
Is all life sacred? Can we then not even eat plants? How about killing bacteria? Some also say spiritually all things are "alive". Is how much you waste from the dead body relevant?
1. You can eat plants and animals - this is Gods order after the flood - but you you must protect them and the environment. 2. You can kill people only in a self protection situation.
The Jains seem to perceive life this way. One way to differentiate is whether - the entity has free will, the ability to consent or not - or is just a biological robot.