In his History and Practice of Civil Actions, Lord Chief Baron Gilbert (p. 205) states that alienage is a disability which must be pleaded to the action, "because it is forfeited to the King, as a rep-isal for the damages committed by the Dominion in enmity with him. In 1 Hale's Pleas of the Crown, (p. 95) it is said "That by the law of England debts and goods found in this realm belonging to alien enemies belong to the King, and may be seized by him," Y. B. 19 E 4, 6, is cited to that effect. The provisions of c. 30 of Magna Charta clearly imply that such confiscation was appropriate under the common law. In case the Crown neglected to seize the debts due the alien enemy the creditor was, upon the termination of the state of war, entitled to sue. Antoine v. Morshead, 6 Taunt. 237.
Aigler, Ralph W. "Privilege of Enemy Aliens to Maintain Actions." Mich. L. Rev. 16 (1918): 621–2.