“History confirms that the Citizenship Clause and the Immigration and Nationality Act (‘INA’) confer citizenship on children based on where they are born, not the ‘primary allegiance’ or loyalty of their parents.” 

“In World War II… the United States confined… enemy aliens… people who had renounced their U.S. citizenship… and people involuntarily transported from Peru… held temporarily as illegally-present aliens in the United States… While in confinement on U.S. soil, some of these people gave birth to children.” 

“Those children were born to declared enemies of the United States awaiting deportation, repatriation, or involuntary prisoner exchange.” 

“The children were also birthright American citizens.” 

“If birthright citizenship was constrained by tests of political loyalty or a parent’s domicile, World War II would have been the moment for that rule to assert itself.” 

“Instead… the United States government adhered unflinchingly to the rule of territorial birthright citizenship.” 

“The histories… show that territorial birthright citizenship survived the greatest loyalty crisis in American history without ever becoming subject to the tests of ‘primary allegiance,’ loyalty, and domicile the Government now claims a right to impose.”