  As we will see, a different version of interpretivism corresponds to each way of reading the claim that institutional practice and morality together ground legal rights and obligations. The first version, hybrid interpretivism, which understands institutional practice as an independent ground, may give rise to a concern of moral bias in the approach to the metaphysical problem. For it is reasonable to suspect that this kind of interpretivist sets out with the goal of finding moral force in the law, and the purpose of combining the institutional base with a moral overlay is to secure such force. On the second version, pure or nonhybrid interpretivism, which reflects the second reading of the distinction, there is no scope for such bias. For according to that version morality mandates the constitutive role that the theory assigns to institutional practice; while there is no nonmorally predefined route through which the practice is supposed to determine any obligations.