The debate between so called interest and will theories of rights is long and well known. I argue that it respect of legal rights it is plausible to claim that there are just two different kinds of normative situations created by rules of law. One of them corresponds to "Interest Rights" while the other to "Choice Rights". Moreover, there are essentially different conditions of plausible ascription of each of those kinds of rights. In view of that I suggest that two kinds of right-holders should be distinguished – creatures able to hold only elementary (interest) rights and those apt to possess personal (choice) rights too. The first category includes all sentient creatures (as non-personal subjects of law) while the other refers to beings possessing qualities of a person. However, extending the scope of legitimate right-holders should not result with any regress in the present level of legal protection enjoyed by human beings. In order to avoid risk of such regress I develop the idea of modestly specist approach to personhood applying different criteria of subjecthood and personhood to human and non-human creatures.Pietrzykowski states
claims to recognize non-personal subjecthood or personhood of non-human creatures should by no means imply depriving any human being of her status. Our fallibility proved by the long list of past scientific and moral misconceptions that have led to abhorrent social and legal practices should prevent us from too easy adoption of any views that could pose any danger of their return.
As a result, I am inclined to think that a reasonable approach to the reconsideration of moral foundations of personhood in law should remain modestly specist. Deeply reformed and non-exclusive version of humanistic specisism I have in mind allows for some relative favor in the treatment of human beings, albeit by no means excludes granting of elementary or even personal rights to non-human creatures. Contrary to radically specist humanism it does not regard human good as practically the only legitimate goal of the law (or at least strongly preempting any other considerations). There is no metaphysical property making all and only members of the human species intrinsically more valuable than any other actual or possible creatures in the world. We (nor anyone else) do not occupy exclusive, superior position in the moral universe justifying absolute priority of our interests over all others.
Moreover, there is no essential connection between humanness and holding elementary rights. Principally, each creature that is able to have subjective interests is a potential candidate to hold some elementary rights (insofar as its interests may deserve protection by means of imposing legal duties on others). Nor is there an essential connection between humanness and personhood. There is only an empirical question whether any non-human creatures posses mental qualities sufficient to have been plausibly conferred with personal rights (and not only elementary rights). At the moment, the answer to this empirical question still seems negative. Nonetheless, there is nothing absurd or even unrealistic by considering creatures that do not meet (or only partially meet) biological criteria of humanness, but possess capacities enabling them to have many kinds of personal rights.
On the other hand, modest specism accepts that there may be different criteria applicable to decide about appropriate legal status of human and non-human creatures. The legal status of non-human creatures (animals or human-animal hybrids, chimeras, artificially intelligent cyborgs, etc.) should be principally dependent on their actual mental capabilities. Those which are sentient may deserve the status of subjects of law (that is, some of their subjective interests may become legally protected as elementary rights). Their status as persons in law would require evidence that they are able to develop actual mental capabilities enabling them to hold and exercise personal rights
It is, however, hardly acceptable to apply the same criteria to human creatures. It would result in a serious decrease in level of their legal protection. Many human beings, e.g. newborns or adults with severe mental dysfunctions would have to be regarded as non-personal subjects of law rather than persons whose rights are exercised by competent custodians (as is the case today). Such conclusions, however, may and should be avoided. The evolution of moral underpinnings of the law should lead to extending rather than shrinking the circle of legal recognition. The concept of non-personal subjecthood may be useful to upgrade the status of the borderline entities, which today are either in an undefined grey area or actually remain deprived of any legal protection whatsoever. In particular, it may concern embryos, pre-implanted zygotes, anencephalic newborns, or human organisms with severely damaged neural structures making them irreversibly unconscious. The intermediate concept of non-personal subjects of law could help to work out more refined and balanced solutions to the problems arising in respect to such kinds of subjects, that seem to not fit either to the category of full persons or mere things.
Regarding human personhood in law, the criteria applicable to human beings should at least allow all of them to count as persons from birth to death (including mentally ill or demented individuals). Thus, the basis to grant personhood to human beings should not be the possession of actual mental capacities sufficient to exercise personal rights. Contrary to other creatures, to be regarded as persons human beings need only sentience. For a human organism to qualify as a non-personal subject of law it has to reveal sole potential for developing sentience or to have been a sentient creature in the past.