I Want Everyone's Opinion on This...

[N-Man]

I think that although there does exist a component of "punishment", what you mainly want to do is remove the killer from society altogether, so he no longer threatens anyone. You can do this by keeping him secluded from society for the rest of his life, or you can simply terminate said life. The latter is more efficient, usually less costly, and accomplishes the same goal.

I will add that holding someone prisoner for all his life is no more or less humane than killing him, unless the conditions in jail are very lax, in which case the punishment is not adequate.

Jail does have one advantage, in the event that the courts f*cked up at some point. If the guy's in jail, he can just be released; if he's dead, he ain't coming back.