Born Free: Roman Jurists on Slavery and Nature

Roman law contained a revealing tension about slavery. Ulpian wrote that 'by natural law all people are born free', and Justinian's Institutes described slavery as an institution of the law of nations 'by which a person is, contrary to nature, subjected to the ownership of another'. Yet Roman society depended heavily on slave labor, and the same law books contain detailed rules about buying, selling and freeing enslaved people.

Jurists resolved the tension by saying that the law of nations, created by human practices such as war, could override natural freedom. This shows how a natural law ideal could be acknowledged in theory while an injustice continued in practice. Centuries later, opponents of slavery would seize on such admissions: if slavery was contrary to nature, why should any legal system tolerate it? The Roman texts thus reveal both the limits of ancient natural law and the seeds of later arguments for abolition.