from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
DEPUTY DISTRICT ATTORNEYS. The Act of Congress of March 3, 1815, 2 Story L.
U. S. 1530, authorizes and directs the district attorneys of the United
States to appoint by warrant, an attorney as their substitute or deputy in
all cases when necessary to sue or prosecute for the United States, in any
of the state or county courts, by that act invested with certain
jurisdiction, within the sphere of whose jurisdiction the said district
attorneys do not themselves reside or practice; and the said substitute or
deputy shall be sworn or affirmed to the faithful execution of his duty.