In contemporary moral and political philosophy, there are two leading approaches to the justification of rights. These could be broadly identified as deontological theories and consequential theories. These two schools of theories each have their own strengths and weakness, while there is also a third contractual approach that is under represented. Because Rawls’ and Scanlon’s well-known contractual theories are designed for purposes other than the justification of rights, the purpose of this paper is to establish a principle of rights on the basis of Rawls’ justification device of the “original position.” First, it supplies a criterion based on human conduct or action. Second, based on this account of human conduct, different types of relationships are constructed and presented to the parties in the “original position.” Third, it will show that the parties in the “original position” would choose one of these relationships as the principle of rights. Finally, Rawls’ first principle of justice will be reformulated. The procedure of choosing a principle of rights in this paper could also be viewed as a demonstration that, when properly situated and motivated, human beings exhibit their potential as rational beings.