The First Circuit found that Frank Monteiro Miranda, a lawful permanent resident who was born in Angola to unmarried parents of Cape Verde citizenship, did not derive citizenship under former section 321 of the INA when his mother naturalized. The Court noted that Angola, Cape Verde, and Massachusetts (the state in which his parents later wed) had all abolished the legal distinctions between legitimate and illegitimate children before Miranda's mother naturalized. Moreover, Miranda's father signed his birth certificate in front of witnesses, evidencing his acknowledgement of paternity. Thus, Miranda did not derive citizenship by virtue of his mother's naturalization. In addition, in light of this legal framework, a second Immigration Judge was not required to give res judicata effect to an earlier Judge's finding that Miranda had derived citizenship.
The full text of Miranda v. Sessions can be found here: