the situations would matter, if your or a loved ones life was in danger of being hurt and you had the chance to kill that person that plans to hurt you or them, i would go after them and if that means kill them... then be it! its self defence!!
well if you have one eye from committing murder and then do it again.... Well yeah. Anyway what's so important about life anyway ? I don't have a kid yet so I can't say I would kill for him/her yet. But i'm pretty sure I would kill to protect my own before I kill to protect myself.
Repeat offenders go blind. I could see murder as acceptable in self defense but only if its impossible for you to subdue the attacker without taking their life.
An eye for an eye leaves the whole world with one eye and no depth perception.
Only in the sense of self defense would I justify murder. Regardless of what they did another wrong will not undo the wrong done, and it's just that much more on your conscience. This is only my opinion.