Berry, Charles T., Joint Force Quarterly
Joint force commanders (JFCs) have routinely exercised authority to reorganize and break apart attached forces under the guise of operational control (OPCON). This exercise has become common practice because of misinterpretations of joint doctrine. Specifically, many officers believe that the authority to direct the internal organization of an attached force is contained within the jointly defined authorities of operational control. This belief is fallacious. Joint doctrine does not delineate the authority to internally organize an attached command or force as an authority inherent to OPCON.
Central to this discussion are several key terms, such as combatant command (COCOM), operational control, and tactical control (TACON), most of which are defined in joint doctrine and worthy of mention herein. Unfortunately, there is an additional term critical to this discussion that is not defined: internal organization.
COCOM, OPCON, and TACON
Combatant command is the authority vested only in combatant commanders by Section 164 of U.S. Code Title 10, or as otherwise directed by the President or Secretary of Defense. (1) Commanders with COCOM can only exercise those command functions or authorities found in Title 10, which specifically defines the command functions that COCOM includes. Moreover, joint doctrine expounds upon the code in Joint Publication (JP) 1, Doctrine for the Armed Forces of the United States. It is also important to note that JP 1 restricts combatant commanders from transferring or delegating COCOM.
JP 1 summarizes COCOM as "the authority of a combatant commander (CCDR) to perform those functions of command over assigned forces involving organizing and employing commands and forces; assigning tasks; designating objectives; and giving authoritative direction over all aspects of military operations, joint training... and logistics necessary to accomplish the missions assigned to the command." (2) COCOM, as defined by JP 1, provides a broad range of command and control that appears appropriate for a commander with permanently assigned forces.
Unlike COCOM, OPCON is not legally defined in law. Instead, it is derived from the authorities of COCOM and delineated in JP 1. Logically, operational control is inherent to COCOM because it is defined as a subset of the COCOM functions (authorities) delineated in Title 10 and JP 1. OPCON provides a much more limited array of command functions than does COCOM. JP 1 states that OPCON "is the authority to perform those functions of command over subordinate forces involving organizing and employing commands and forces, assigning tasks, designating objectives, and giving authoritative direction necessary to accomplish the mission." (3) Operational control is the command relationship normally transferred to a gaining combatant commander when forces are attached. The rationale for this appears sound, given that the attachment of forces is a temporary transfer normally associated with the accomplishment of a specific mission and the citation above ends with "necessary to accomplish the mission."
A current example of this is the rotational deployment of I Marine Expeditionary Force units to Iraq and Afghanistan, which is facilitated by a change of operational control between U.S. Pacific Command and U.S. Central Command. Only the Secretary of Defense or President can authorize the transfer of forces and change of operational control as described.
Combatant commanders cannot delegate OPCON outside of their commands, but they can delegate it within their commands. Moreover, any commander who has operational control of a force can delegate that authority within his command. OPCON is designed in this manner to provide commanders with the requisite authority to organize their commands, delegate the appropriate level of authority, and assign tasks to subordinate commanders as necessary to accomplish the mission. …