Justice among Nations tells the story of the rise of international law and how it has been formulated, debated, contested, and put into practice from ancient times to the present. Stephen Neff avoids technical jargon as he surveys doctrines from natural law to feminism, and practices from the Warring States of China to the international criminal courts of today.

Ancient China produced the first rudimentary set of doctrines. But the cornerstone of later international law was laid by the Romans, in the form of natural law--a universal law that was superior to early laws and...