The American Psychiatric Association (not the other, larger "APA" which is the American Psychological Association) does indeed automatically adopt the American Medical Association's "Principles of Medical Ethics" as its own ethical foundation. APA long ago decided that, being an organization of physicians, all members should first meet the ethical principles of medical doctors, then also meet those specific to the practice of psychiatry (known in the APA version as "Annotations Especially Applicable to Psychiatry").

One may note that these principles and annotations are specific and limited -- as to any "official" standing -- to the organizations which promulgate them. While they may be a great set of guidelines, they are enforceable only by the organizations themselves, and only against members of those organizations. Professional ethics are not matters of law unless the particular ethics matter has been separately adopted by some governmental body as law or rule (cf., clinician-patient sexual behavior in most states). That's one reason I sometimes suggest that patients and their families choose therapists who belong to a major professional organization that has written ethics canons. In such cases, the clinician's personal ethical standards (the most important thing) are backed up, to some extent at least, by the organization's expectations.

Someone else will have to comment on the "political" issues.