The only problem I can actually name with vigilante justice is that it can be error-prone. Otherwise it's only an encroachment upon the state's monopoly on the

The only problem I can actually name with vigilante justice is that it can be error-prone. Otherwise it's only an encroachment upon the state's monopoly on the dispensation of justice, and I'm not seeing a moral objection to that. And the state's approach to justice is also quite error-prone.