Abolishing Ius Sanguinis Citizenship: A Proposal Too Restrained and Too… 107 increase the likelihood of abusive denials of citizenship by officials who, at least in the U.S., are often all too eager to find reasons to reject claims to citizenship.6 In the case of nonmarital children – who make up a far greater portion of the global population than children conceived through ART – the restriction of parent-child citizenship transmission to ‘primary caregivers’ could lead to circumspect treatment, or outright rejection, of the father-child relationship as a basis for citizenship transmission. Indeed, the primary caregiver standard could stymie the caregiving efforts of unmarried fathers who are divided by nationality from their children, and hence may never be able to establish themselves as the ‘primary caregiver’. The emphasis on caregiving as a prerequisite could also aid unmarried fathers who prefer to avoid parental responsibility by distancing themselves geographically from their children. The result: a ius sanguinis citizenship regime that would buttress gender inequality by undermining men’s parental rights and helping them to avoid their parental responsibilities.7 Moreover, and regardless of one’s view of the equities as between parents, it is ultimately the nonmarital child’s citizenship and migration rights that could be destabilised, depending on how officials understood the concept of ‘social parent’. Dumbrava recognises the inequities associated with ‘the differential treatment of children born within and out of wedlock with respect to access to citizenship’, but his solution – to abolish parent-child citizenship transmission altogether – would give cold comfort to nonmarital children and marital children alike. This is not an endorsement for a purely genetic model of citizenship transmission. Despite the references to ‘blood’, ius sanguinis citizenship has never rested on purely biological conceptions of citizenship. Traditionally, marriage was fundamental to the ability of fathers to secure citizenship for their children, and – at least in the development of U.S. law – the presumption that the mother is the sole caregiver of the nonmarital child led to the recognition of the mother-child relationship as a source of citizenship for foreign-born nonmarital children.8 Rather, I suggest that – unless and until we move beyond citizenship as the enforcement mechanism for basic human rights, and beyond the family as a foundational source of material and psychological support for children, we cannot overstate the importance of 6 7 8 See, for example, Saldana Iracheta v. Holder, 730 F.3d 419 (5th Cir. 2013). I develop this argument in: Collins, K.A. (2000), ‘When Fathers’ Rights Were Mothers’ Duties: The Failure of Equal Protection in Miller v. Albright’, Yale Law Journal (109) 1669–1708 (1699–1705), and in ‘Illegitimate Borders’, above n. 2, at 2230–34. See Collins, ‘Illegitimate Borders’, above n. 2, at 2199–2205.