This book by Roberto Esposito - a leading Italian political philosopher - is a highly original exploration of the relationship between human bodies and societies. The original function of law, even before it was codified, was to preserve peaceful cohabitation between people who were exposed to the risk of destructive conflict. Just as the human body's immune system protects the organism from deadly incursions by viruses and other threats, law also ensures the survival of the community in a life-threatening situation. It protects and prolongs life.

But the function of law as a form of...