Crime And Punishment For Psychopaths
The Moussaoui jurors shared a liberal misunderstanding of why society punishes criminals. They thought that it was all about him, whereas it was actually all about deterring his emulators. That confusion will be fatal.
What follows is drawn from Steven Pinker's work - from memory since the book is at my other base, so any errors are my own.
Liberals argue that capital punishment "won't bring the victim back". But of course neither will jailing leg breakers make legs whole, or jailing burglars restore possessions, but we still (usually) jail the perps.
Human societies punish predatory behavior because, to the extent that punishment discourages future emulators, they prevent hundreds, thousands, or millions of future crimes.
So Moussaoui's punishment should have been set to deter future mass murderers. That's tough, because he's a psychopath (his gloating over the 9/11 human agonies is classic indicator). He's one of the 2 - 3% of men who lack all feeling for other humans, because a specific part of their brain is broken.
Psychopaths have minds like spiders, but they can be deterred by potential punishments much more powerful than needed to deter normal people. Our ancestors knew this, and would have executed Moussaoui publicly and with great cruelty.
We've stopped doing that, but faced with a psychopathic enemy, we need to relearn it.