Now theoretically you could go a layer deeper and suppose that those natural rights are themselves based on a certain group or culture's morality judgement, although that would be contradictory to their essence as "natural"
Now theoretically you could go a layer deeper and suppose that those natural rights are themselves based on a certain group or culture's morality judgement, although that would be contradictory to their essence as "natural"
Governments kill people all the time, and do so quite legally.
Some governments do it more than others. But, as far as the US government is concerned, it happens to have the one of the world's largest contingent of hired killers. And they spend more money than all of the rest of the world combined to train them to kill and to facilitate killing and on giving them the means to do so.
And this doesn't even begin to cover the vast array of other people and situations in which killing is not only permitted, but considered a duty -- from police killing a some suspect trying to get away or resisting arrest to your average homeowner killing an intruder in their home, etc..
So when you talk about "laws against killing", you're really talking about "laws against certain kinds of killing in certain kinds of situations" and also "laws that specifically allow or even require killing in certain situations".
While most societies do have laws against "murder", what that usually boils down to is "certain kinds of illegal killing". Precisely what qualifies as "illegal killing" and what in which situations killing is allowed or even encouraged varies from society to society and certainly from individual to individual (take pacifists and believers in non-violence vs soldiers for example).