(1) a particular human being, because of specific, volitional conduct (not in any way based upon sex, race, class, or whathaveyou) of which he has been duly convicted with all the procedural rights and guarantees our society affords, has placed himself beyond the protection ordinarily afforded to human beings in the law, even most convicted criminals. and (2) a class, race or group of humans are outside the protection of the law simply by virtue of their membership in the class, race or group.
It's not saying the perp is merely an animal to slaughtered, but it is saying we cannot permit them to live and should not expend resources on them.
I realize there is a danger that my argument from practical necessity can be seen as a utilitarian argument, but it it is not so intended. I am arguing that we must allocate scare resources, and in making those allocations we must choose among competing priorities and that society makes moral judgments about those priorities (e.g. a transplant operation for a poor kid is a morally better use of scarce tax money than a comfortable old age for Charles Manson - is not an appeal to more happiness for more people). None of the priorities are lexically ordered. The utilitarian argument (the "greatest good for the greatest number" in it's simplist form) makes the greatest good for the greatest number itself a moral criterion which is lexically ordered and precedes other criteria.