A code of ethics, whether in the corporate world, in government, in the medical field, or in any other endeavor or profession can only be effective if:
1) All members of the organization are briefed on and issued the code, and
2) An effective enforcement mechanism or policy exists to ensure that violations are identified and perpetrators punished.
A code of ethics that is treated as voluntary and the enforcement of which is arbitrary or nonexistent will fail to penetrate corporate culture and influence how decisions are made. The enforcement mechanism must be universally perceived as impartial and just. Corporate officers cannot be seen as being "above the law." The code of ethics must be followed from the top of the corporate ladder to the bottom.
Professions, for example, law and medicine, that are highly dependent upon high levels of personal integrity suffer greatly -- as do clients and patients -- when codes of ethics are nonexistent or exist on paper but are routinely ignored.