I was reading about the Roman practice of homo sacer and thought it was interesting how people subjected to it were explicitly said to not be allowed to be used in a religious sacrifice. Was this because the Roman taboo against human sacrifice was so strong that it applied to people otherwise considered to have lost the status of a legal person or was it because these individuals were considered to be "unfitting" to be offered to the gods or was it something else?
I would note that the Romans did use human sacrifices at extreme moments - during the Hannibalic war when they buried alive a pair of Gauls and Greeks. Holt Parker also makes an argument that the Vestal Virgins were human sacrifices since they generally were found to have been unfaithful at the same time as major crisis. Parker argues that the virgins represented an unconquered/unbreached city of Rome and they acted as a pharmakos when things weren't going well.