In modern America, we do not punish immoral behavior. We have a judicial system that addresses illegal behavior, but illegal and immoral are not necessary the same thing. For example, committing adultery is an immoral act but not an illegal one.
Only behavior that breaks the law can be punished; these punishments, furthermore, must not be "cruel and unusual." Dante's punishments, on the other hand, would definitely be considered cruel and unusual by modern American standards.
Today, we punish immoral (but not illegal) behavior by public shaming. That is, a woman who has been cheated on will often take to social media to publicly shame her husband. By bad behavior "going viral," people are punished for bad behavior outside a formal punishment. It should be noted, however, that public shaming might be considered cruel and unusual, so Dante might just have approved!
