The incapacities of femes covert provided by the common law apply to their civil rights and are for their protection and interest. But they do not reach their political rights nor prevent their acquiring or losing a national character. Those political rights do not stand upon the mere doctrines of municipal law applicable to ordinary transactions, but stand upon the more general principles of the law of nations.
This says the common law does not affect citizenship of women who are married to foreigners. It falls under the law of nations. So far as natural-born citizenship would have been understood, that meant that any woman who married a foreigner did not have her citizenship (or the citizenship of her child) established or protected by the common law. The law of nations would be the guide, meaning the citizenship of the child naturally follows that of the father, as Vattel said. The Minor court was being generous when it said "parents who were citizens" because the rule would still be guided by the citizenship of the father. The mother automatically follows the citizenship of her husband. This would also seem to be a guide on expatriation.