Family Matters: Modernise, Don’t Abandon, Ius Sanguinis 99 ART requires fixing family and citizenship law I agree with Dumbrava’s and Bauböck’s rejection of exclusive, unconditional ius sanguinis rules as inadequate in dealing with the consequences of ART and modern family law. I disagree, however, with the conclusion Dumbrava draws from his argument that ‘joint citizenship adds little to the legal and normative character of the parent-child relationship’. In fact, the permanence and stability stemming from common citizenship among close family members can have profound consequences for the unity required to develop and maintain family relationships. I also disagree with Dumbrava’s argument that ‘the main problem’ is that ius sanguinis ‘is parasitic on external factors concerning the legal determination of parentage’. In fact, some federal States already delink federal citizenship determination and state or provincial family law,3 creating greater problems than do citizenship laws that reflect legal parentage. In the United States, for example, legal parentage is generally a matter of state law. Yet, the US Constitution defines citizenship as an exclusively federal matter,4 and Congress has established and revised a complex, autonomous algorithm for determining when a citizen parent transmits US citizenship to a child born abroad.5 The problematic example Dumbrava points out regarding parents’ inability to transmit US citizenship to children conceived through ART was created by a misguided autonomous federal policy, not parentage determinations under family law.6 It could, and should, be 3 4 5 6 HCCH (2014), A Study of Legal Parentage and the Issues Arising from International Surrogacy Arrangements, Prel. Doc. No 3C. Hague Conference on Private International Law,66–68 (listing Australia, Canada and the United States as examples). Available at http://www.hcch.net/upload/wop/ gap2015pd03c_en.pdf The Fourteenth Amendment guarantees that ‘[a]ll persons born or naturalized in the United States and subject to the jurisdiction thereof are citizens of the United States and the state in which they reside’. Not only does this Amendment adopt a nearly absolute ius soli rule, but it clarifies that citizenship is a purely federal matter, with no meaningful state role beyond establishment of its own standards for recognising state residence. 8 USC §§1401–1409. Available at http://www.uscis.gov/sites/default/files/ ilink/docView/SLB/HTML/SLB/0-0-0-1/0-0-0-29/0-0-0-9696.html Under current US law, a genetic and legal father and/or one or more legal and ‘biological’ mothers (i.e., genetic and gestational mother(s)) transmit birthright citizenship to children conceived through ART, but non-biological parents do not. Titshaw, S. (2014), ‘A Transatlantic Rainbow Comparison: “Federalism” and Family-Based Immigration for Rainbow Families in the U.S. and the