Executive orders have the full force of law when they take authority from a legislative power which grants its power directly to the Executive by the Constitution, or are made pursuant to Acts of Congress that explicitly delegate to the President some degree of discretionary power (delegated legislation).[1]
John Contrubis, Executive Orders and Proclamations, CRS Report for Congress #95-722A, March 9, 1999, Pp. 1-2
(https://en.wikipedia.org/wiki/Executive_order#cite_note-1957print-1)