The MLIS program I’m enrolled requires that all its students take an ethics course. This is, of course, not to imply that MLIS student are knavish rakes who the program administrators strongly suspect need to be drummed in ethical principles. It is to imply that I took the course and had to write long paper, the conclusion to which I’m excerpting below.
Ethics codes work by the principle of exclusion. The core message any code of ethics carries is that there are specific principles that the members of the association uphold. Since no code of ethics provides a comprehensive list of values or attempts to adjudicate unequivocally between competing values, the inescapable conclusion – even if the association is loathed to put an official stamp on it – is that values explicitly embraced by the code take precedence over those left unmentioned. As one of the authors of the AALL Ethical Principles writes, a code of ethics “favors certain values that must be consciously overcome if library policy is made to the contrary” (Monaco, 1997). In brief, values mentioned are esteemed over values absent.
Even this attempt to pin some specifics onto eel-like nature of codes of ethics still leave open the issue of how to interpret the values that are written down in the text since they tend to be incarnated in such general forms as to allow for an incredibly wide range of plausibilities. This is really an intractable problem; any document that purports to speak on issues as elusive and contentious as values will inevitably call forth conflicting interpretations. Thus, codes of ethics are not to be judged in how unambiguous they managed to make their authorial voices but rather how relevant they are to those whose behavior they are meant to guide and reflect.
Yet the AALL holds itself above being judged by this metric. It mounts no show of evidence to show how relevant its Ethical Principles are – no case studies, no “feel-good” anecdotes, no testimonials by various professionals about how the codes of ethics guide their working lives, no ongoing surveys of members’ opinions, nothing but its own existence to assert its importance. Perhaps it is as one of the creators of the AALL Ethical Principles said, [the code’s] very existence informs the profession itself, and those its serves, of the core values of its practitioners.” It is existence that matters; consultation and relevance are presumed.
 This interpretation includes figuring out the delineation between values in the code, values implied by those covered in the code, and values outside of the code.