Hypothesis: all law is fundamentally commercial law. I.e. defense of possession underlies the original assertion of law. The first law: "Mine, not yours."
Evidence:
Robbery and adultery (i.e. trespass on man's property) were capital crimes, along with murder and rape, in the oldest surviving legal code, that of Ur-Nammu.
The origin of law coincides with the advent of agriculture.
The Peace of Westphalia, ending the Thirty Years War in 1648 and establishing the modern principle of state sovereignty, was "a great property settlement for Europe, a quieting of title across the continent." (Janis, International Law)
