To some extent the very nature of ethics should be self enforcement. Those with ethics don't need to have a standard of conduct forced on them. The problem of enforcement only arises when somebody is accused of unethical conduct and either denies it or does not recognize the conduct to be below standard.
Ethics are mostly a matter of personal definition.
I define what is ethical for me and you define what is ethical for you. When I decide that I can determine what your ethics should be then I am being rude and meddling in affairs which are not my own. There is however a minimum standard of ethical conduct for municipal employees and officials. This is the Municipal Officers and Employees Ethics Act. The enforcement is two fold.