This chapter is a jurisprudential/philosophical consideration of exactly why biological diversity should be protected through a consideration of how the different ‘interest groups’ involved might value biodiversity. These interest groups are identified as biospheres, which have to date received limited attention in international law as ‘entities’ deserving of protection; threatened species, whose ‘direct interests’ in the protection of biodiversity have similarly received little attention; individual members of threatened species, which tend to be valued proportionately to their usefulness to humans and not to be accorded any interests deserving of protection if they are neither ‘useful’ nor ‘native’; the Earth itself, which receives scant direct attention in international instruments; and humanity, which arguably is the most highly valued species but perhaps not justifiably so. The chapter then weighs up different values, before applying its findings to the ‘moral considerateness’ of species labelled as ‘pests’, and whether such a classification automatically leads to such species losing their status as morally considerate beings. The argument is made that moral considerateness imposes limitations on how society regulates all species, including unwanted ones. There is then consideration of how different interests might be reconciled through the medium of justice in a national legal system – the particular case of New Zealand with the particular species of the ‘alien’ possum is used as an example.