Recognizing that the Citizenship Clause applies in States and Territories alike is consistent with its purpose and the historical context in which it was ratified. The Citizenship Clause was adopted to constitutionalize the well-settled common-law principle of jus soli, or “the right of the soil,” that extended birthright citizenship “within the dominion” of the sovereign, long understood in England and the United States to include territories. The only time the Supreme Court did not follow the jus soli rule was its infamous ruling in Dred Scott v. Sandford. Significantly, the Citizenship Clause was adopted to “overturn the Dred Scott decision.” 

The Fourteenth Amendment’s Framers sought “‘to put th[e] question of citizenship and the rights of citizens . . . beyond the legislative power’” and to restore and cement the settled jus soli rule. In short, “[t]he Fourteenth Amendment … has conferred no authority upon Congress to restrict the effect of birth, declared by the Constitution to constitute a sufficient and complete right to citizenship.”

More information can be found in Section III.A.3 of Michael Pese’s Motion to Dismiss and also this legal brief filed by prominent citizenship scholars from across the ideological spectrum.