The conquest, occupation, and settlement of the Americas was the first large-scale European colonizing venture since the fall of the Roman Empire. Like the Roman Empire, various occupying powers acquired overseas possessions in territories in which they had no clear and obvious authority. Their actions demanded an extensive reexamination, and sometimes reworking, of whole areas of the legal systems of early modern Europe, just as they threw into question earlier assumptions about the nature of sovereignty, utterly transformed international relations, and were ultimately responsible for the evolution of what would eventually come to be called “international law.”

Broadly understood, the legal questions raised by this new phase in European history can be broken down into three general categories: the legitimacy of the occupation of territories that, prima facie at least, were already occupied; the authority, if any, that the colonizers might acquire over the inhabitants of those territories; and – ultimately the most pressing question of all – the nature of the legal relationship between metropolitan authority and the society that the colonists themselves would establish.