​Beheading is not an uncommon undertaking. As a particularized physical violence, it has been practiced by all societies and civilizations at some point in their history. In fact, for millennia public beheadings around the world were routine. In contemporary international society some states and many non-state actors regularly engage in this undertaking.

This begs the obvious question: why put a human being through this unimaginable cruelty? While the idea of execution by decapitation appears visceral and horrific, it has always been grounded in cultural, religious and political...