The definitions of these instruments, including the differences between them, are not easily discernible, as the U.S. Constitution does not contain any provision referring to these terms or the manner in which the President may communicate directives to the executive branch. When they are founded on the authority of the President derived from the Constitution or statute, they may have the force and effect of law.... As such, authority for the execution and implementation of these written instruments stems from implied constitutional and statutory authority. Despite the amorphous nature of the authority to issue executive orders, presidential memoranda, and proclamations, these instruments have been employed by every President since the inception of the Republic. Jackson's concurrence, as discussed below, is based on the proposition that presidential powers may be influenced by congressional action. Presidential Revocation and Modification of Executive Orders

Executive orders are undoubtedly one of many tools available to Presidents to further policy goals during his Administration.
Executive orders, presidential memoranda, and proclamations are used extensively by Presidents to achieve policy goals, set uniform standards for managing the executive branch, or outline a policy view intended to influence the behavior of private citizens. The U.S. Constitution does not define these presidential instruments and does not explicitly vest the President with the authority to issue them. Nonetheless, such orders are accepted as an inherent aspect of presidential power. Moreover, if they are based on appropriate authority, they have the force and effect of law. This report discusses the nature of these written instruments, executive orders in particular, with a focus on the scope of presidential authority to execute such instruments, as well as judicial and congressional responses to their issuance.