Eighteen rules for writing a code of professional ethics

Most professional societies, scientific associations, and the like that undertake to write a code of ethics do so using other codes as models but without much (practical) guidance about how to do the work. The existing literature on codes is much more concerned with content than procedure. This paper adds to guidance already in the literature what I learned from participating in the writing of an important code of ethics. The guidance is given in the form of "rules" each of which is explained and (insofar as possible) justified. The emphasis is on procedure.