The rationale for territorial birthright citizenship has its basis in the feudal system of early England, where ligeance to a king or lord was a component of the feudal relationship.(20) The feudal system engraved into English governance the concept of jus soli,(21) the formulation of a citizenship rule founded not on heredity or parentage but territorial birthright.(22) Lord Coke acknowledged this basis in explaining the mutual relationship of the ligeance owed by the sovereign and the subject.(23)
The first prohibits children born of the Crown's enemies within the Crown's realm during time of hostility from becoming subjects; the second prohibits "issues" from foreign ministers or consuls, born in the Crown's realm, from becoming subjects.(24) These corollaries are components of the concept of ligeance described in Calvin's Case.
Coincidentally, Lord Coke's opinion indicates that the parent's nationality does not negatively impact the status of the "issue," so long as the parent does not fit into one of the prohibited categories.(26) While the parent's ligeance may be "momentary and uncertain," there is sufficient obedience that a child will be a natural born subject.(27) This creates an opportunity for plausible subscription to the theory that children of illegal immigrants are thus citizens by fact of birth within the territory.
Calvin's Case stands for the proposition that, with certain limited exceptions founded on a ligeance requirement, a child born within a sovereign's territory is a sovereign's subject, or, in modern parlance, a citizen.
By altering common law territorial birthright citizenship, the United Kingdom made a policy decision defining British citizenship based on the child's bond to the United Kingdom as evidenced by the citizenship status of their parent.(144) The alteration of 375 years of common law signified a departure from the importance of the territorial component, as expounded by Coke in Calvin's Case, and an acceptance of the mutual bond theory that is the basis of Lockean consent theory.(145) The birth of a child within the territorial limits of the United Kingdom is not the sole factor to determine British citizenship because consent of the sovereign (or ligeance) is not established, that is, a child's parentage under the British Act is not established.
While the child may be born in the United States, the child, under the opponents' theory, is not subject to the jurisdiction because his parent is not under the ligeance, or consent in modern parlance, of the U.S.
rule of territorial birthright citizenship is fortified by Calvin's Case, which expounded the territorial nature of ligeance and manifests consent broadly,(166) limited only by the common law exceptions for children born of diplomats and children born of hostile occupying forces.(167) Despite the status of the immigrant parents, jurisdiction over the child is not absent so long as he is present within the territorial definition of the United States.(168)
(12.) An "alien" was defined in Calvin's Case as a "subject that is born out of the ligeance of the King and under the ligeance of another." 77 Eng.
According to the defendants, Calvin was not a subject of King James' realm of England because Calvin was not under the ligeance of the king's body politic in England.