Libertarianism is a political philosophy of non-aggression against the person and property of individuals. But it is not a political philosophy of
non-retaliation. If it were, not merely capital punishment, but imprisonment as well, would be incompatible with it.
I had been under the impression that the whole point of libertarianism is opposition to the power of the state.
Few libertarians oppose the punishment of crime, legitimately defined. An anarchocapitalist would wish to separate this function from the state; a minarchist would see this as one of government's only legitimate functions. In either case, there is no inherent conflict with capital punishment.
There are, of course, numerous philosophical trappings when it comes to libertarian law enforcement. For who is to be the judge of whether a person is actually guilty, and where does he (or they, it, whatever) get this authority? Someone's rights are, in some sense, going to be held at the mercy of others. But this is equally true when it comes to imprisonment or even imposition of a fine.
Al, haven't we learned by now that *ahem* "libertarians" are only for liberty for rich, white, protestant men? Respectable people who know their place in society.
We are not for the equal liberty of criminals.