In this book we have tried to demonstrate the important role that customary law plays in modern, western society. We have explored the importance of sustainability and the search for legal systems that can provide cautious avenues for achieving sustainable objectives. And we have looked at the growing importance of international law's recognition of both sustainablility and custom. We have explained that customary law is an alternative to “governmental control and command.”

The importance of customary law

In order to understand the role of customary law today, we need to reemphasize some basic philosophical principles. We must acknowledge that humans have the capacity to formulate rules to guide cooperative behavior relating to each other and to their surrounding environment. We need to emphasize that customs are not simply reflex responses to outside stimuli, but are developed intuitively by humans who seek to benefit by cooperation.

Enlightenment philosophers argued that this rationalist capacity distinguished humans from the other animals. Although modern science may blur the lines between humans and animals, and between rational and instinctive behavior, it remains unquestioned that humans surpass all other species in the extent of their ability to use rational processes to establish customary rules.

Customary law exists whenever people act as if they were legally bound to observe customary rules. No endorsement by any legislative, judicial or administrative body is needed to create customary law if people accept rules as the law. Customary law is pervasive in modern societies.