Nathan Perl-Rosenthal and Sam Erman have published, open access," Inventing Birthright: The Nineteenth-Century Fabrication of jus soli and jus sanguinis," in Law and History Review:
Formal membership in a state has been an essential political status for well over a century. It is typically gained at birth, either jus soli or jus sanguinis. Jus soli assigns nationality by birth in a nation's territory; jus sanguinis assigns children their parents’ nationality. This article provides an alternative intellectual history of the modern dominance of these principles for attributing nationality. Contrary to prior scholarship, soli and sanguinis were not restatements of existing principles. The soli/sanguinis binary was a nineteenth-century invention. Old-regime European empires attributed membership in the community under one or another single natural law principle. Parentage and birthplace were mostly evidence of conformity. In the early nineteenth century, officials in multiple jurisdictions began prioritizing positive law above natural law and transformed parentage and birthplace into competing principles for assigning nationality. This movement crystallized in 1860 when Charles Demolombe introduced jus soli and jus sanguinis to nationality law as competing, ostensibly ancient legal traditions. The framework spread quickly because it was a useful way to assign nationality despite states’ conflicting approaches to political membership. Yet, as its role in United States v. Wong Kim Ark (1898) helps illustrate, the invented tradition has also obscured our understanding of more complex historical dynamics.
--Dan Ernst