 What does a creature have to do, or be like, to be included within the scope of (at least some) principles of justice? Most past philosophers have assumed that the line should be drawn so as to exclude all non-human animals, but more recently some have been prepared to defend ‘justice for animals’ (Nussbaum 2006, ch. 6; Garner 2013). Against this, Rawls asserts that although we have ‘duties of compassion and humanity’ towards animals and should refrain from treating them cruelly, nonetheless they are ‘outside the scope of the theory of justice’ (Rawls 1971, p. 512; Rawls 1999, p. 448). How could this claim be justified?