Some of the answers to my question Are academic ethics global or local? indicate the possibility that academic ethics themselves (rather than just laws and policies affecting academics) may change over time.
What is the actual process by which academic ethics may be altered? More specifically, is the process:
Top-down, in which regulatory agencies, funding sources, legislatures, etc. push down new rules onto academics, who are expected to internalize them as normative? (e.g. "Please take note that fooing the bar is now against our Code of Ethics. If you do not cease all bar fooing activity by the end of the fiscal year, your grant will not be renewed.")
Bottom-up, in which written codes of ethics, laws, funding guidelines, etc. are modified as time goes on to match popular consensus? (e.g. "According to our recent surveys, 95% of academics and 82% of the general public Agree with the statement 'It should be considered unethical when academics foo the bar.'. For the 2020 fiscal year, we should make not fooing the bar a requirement for funding.")
The question can alternately be phrased as asking about the nature of academic ethics themselves - whether the "true state" of what is ethical and what is not is part of written rules of academia (and thus reflected in applicable policies, laws, procedures, etc.), or part of the unwritten rules.