<P> According to an April 2007 memorandum opinion by the United States Department of Justice's Office of Legal Counsel, addressed to the general counsels of the executive branch, defined "officer of the United States" as: </P> <P> a position to which is delegated by legal authority a portion of the sovereign power of the federal government and that is' continuing' in a federal office subject to the Constitution's Appointment Clause . A person who would hold such a position must be properly made an' officer of the United States' by being appointed pursuant to the procedures specified in the Appointments Clause . </P> <P> The difference between an "Officer of the United States" and a mere "Employee of the United States," therefore, ultimately rests on whether the office held has been explicitly delegated part of the "sovereign power of the United States". Delegation of "sovereign power" means possession of the authority to commit the federal government of the United States to some legal obligation, such as by signing a contract, executing a treaty, interpreting a law, or issuing military orders . A federal judge, for instance, has been delegated part of the "sovereign power" of the United States to exercise; while a letter carrier for the United States Postal Service has not . Some very prominent title - holders, including the White House Chief of Staff, the White House Press Secretary and most other high - profile presidential staff assistants, are only employees of the United States as they have no authority to exercise the sovereign power of the federal government . </P> <P> In addition to civilian officers of the United States, persons who hold military commissions are also considered officers of the United States . While not explicitly defined as such in the Constitution, this fact is implicit in its structure . According to a 1996 opinion by then - Assistant Attorney General Walter Dellinger of the Justice Department's Office of Legal Counsel, "even the lowest ranking military or naval officer is a potential commander of United States armed forces in combat--and, indeed, is in theory a commander of large military or naval units by presidential direction or in the event of catastrophic casualties among his or her superiors ." The officer's authority to command the forces of the United States draws its legitimacy from the president himself as "Commander in Chief of the Army and Navy of the United States"; the president cannot reasonably be expected to command every soldier, or any soldier, in the field and so delegates his authority to command to officers he commissions . </P>

Who are considered civil officers of the united states