As well as the custodial sentences they will undoubtedly get, it would serve them right if a drop of acid was placed on the backs of each of their hands. This would give them a miniscule indication of the sort of suffering their victims were having to endure.
It might well serve them right - they clearly lack a functioning sense of empathy/theory of mind, so a taste of "This is why it's wrong; it's not nice, is it? So therefore it's not nice to others" might break through.
On the other hand I'm not sure how the legal and state-sanctioned administrator of that drop of acid would differ from the owner of the hand. In fact the former may be worse - in the sense of more morally culpable - than the latter. Somebody with little or no empathy who throws acid at someone is a criminal, certainly affectively deficient and in at least some cases mentally ill; someone to whom none of those qualities apply who is allowed to drop acid on someone because the law allows for it has no excuse to hide behind.
Rhiannon said that fighting barbarism with barbarism achieves nothing. Firefighters fight fire with water and foam, not with fire. That would be a stupendously silly thing for a firefighter to do.
