The English word [law] derives from the Anglo-Saxon word [lagu]; this in turn comes from the Old Norse [lag], which means layer or stratum. Law is [That which is laid down, ordained, or established; a body of rules of action or conduct prescribed by controlling authority and having a binding legal force] (Black 1990, 884). It is the body of rules, regulations, or principles that have been prescribed by authority or established by custom; and which a society, nation, state, or community recognizes and enforces as legally binding on each of its members; and which must be obeyed and followed by all citizens subject to sanctions. These rules of conduct are embodied in the sources of our law in the United States.
For the professional nurse, laws provide a basis for nursing intervention in the provision of care to patients; they act to distinguish the roles and responsibilities of the nurse from those of other health care providers; and they define the boundaries of dependent or autonomous practice in various roles and clinical settings.
There are four sources of law in the United States.