Does a basic human right to subsistence in turn mean that the needy are morally permitted to take and use other people's property to get out of their plight? Should we respect the exercise of this right of necessity in a variety of scenarios - from street pickpocketing and petty theft to illegal squatting and immigration? In this concise and accessible book, Alejandra Mancilla addresses these complex and controversial moral questions. The book presents a historical account of the concept of the right of necessity - from the Medieval writings of Christian canonists and theologians to eighteenth century natural law theory. The author then goes on to propose some jointly sufficient conditions for its exercise, grounded in a minimal conception of basic human rights. She confronts the main objections that may be posed against this principle and ultimately concludes that the exercise of this right should be considered as a trigger to secure a minimum threshold of welfare provisions for everyone, everywhere.