Resistance theory is an aspect of political thought, discussing the basis on which constituted authority may be resisted, by individuals or groups. In the European context it came to prominence as a consequence of the religious divisions in the early modern period that followed the Protestant Reformation. Resistance theories could justify disobedience on religious grounds to monarchs, and were significant in European national politics and international relations in the century leading up to the Peace of Westphalia of 1648. They can also underpin and justify the concept of revolution as now understood. The resistance theory of the early modern period can be considered to predate the formulations of natural and legal rights of citizens, and to co-exist with considerations of natural law.
Any "right to resist" is a theory about the limitations on civil obedience. Resistance theory is an aspect of political theory; the right of self-defence is usually taken to be a part of legal theory, and was no novelty in the early modern period. Arguments about the two concepts do overlap, and the distinction is not so clear in debates.