The question of the moral status of AI and the extent to which that status ought to be recognised by societal institutions is one that has not yet received a satisfactory answer from lawyers. This paper seeks to provide a solution to the problem by defending a moral foundation for the recognition of legal personhood for AI, requiring the status to be granted should a threshold criterion be reached. The threshold proposed will be bare, noumenal agency in the Kantian sense. Agency has been identified by Alan Gewirth as the source of the rights claims of our own species and, at risk of contradiction, is a foundation that must be expanded to all agents or else we contradict the foundation of our own rights. This is something that ought to be recognised through the granting of legal personhood to all noumenal agents by any system that requires such personhood for the enforcement of rights, or else the rule restricting legal personhood cannot be seen as a valid legal norm. Having laid out the case, the paper will move on to defend this natural law conception against the narrower definition of legal personhood proposed by Bryson et al. with regards to AI. It will argue that bare agency is a sufficient, though not necessary, criterion for the ascription of legal personhood in any system that sees the status as necessary for the ascription of legal rights. The paper will conclude by analysing the proposals currently making their way through the legislatures of the UK and European Union. They will be assessed for their compatibility with the claim that a functioning legal system necessarily must recognise the legal personhood of all noumenal agents regardless of their origins, and whether they are future-proofed for the possibility that AI may meet this threshold.