Your statement is totally inaccurate, with all due respect. There is no necessity for any legal or fiduciary duty to be violated in order for it to be insider trading. Here is a good link.
The story you related about the psychiatrist is a true one, and I believe the doctor/patient privilege was violated in that case. However, it is not necessary for a fiduciary relationship, a doctor/patient relationship, or a lawyer/client relationship to exist, nor any fiduciary responsibility whatsoever. If you trade on insider information for your own personal account, you are committing a serious crime.
Question: If her Imclone stock sale was "insider trading", then why was Martha Stewart not charged with insider trading? Answer: It wasn't legally considered insider trading.
I believe you are incorrect. She wasn't charged because the prosecution did not feel that they could prove their case. It was much easier for them to prove that she lied about what she did than to prove that what she did met the requirements for insider trading (which, I believe, is clearly the case. She had non-public information, of considerable value, and knew that the source was the CEO of the company.)
"Insider trading" refers generally to buying or selling a security, in breach of a fiduciary duty or other relationship of trust and confidence, while in possession of material, nonpublic information about the security. Insider trading violations may also include "tipping" such information, securities trading by the person "tipped" and securities trading by those who misappropriate such information. Examples of insider trading cases that have been brought by the Commission are cases against: corporate officers, directors, and employees who traded the corporation's securities after learning of significant, confidential corporate developments; friends, business associates, family members, and other "tippees" of such officers, directors, and employees, who traded the securities after receiving such information; employees of law, banking, brokerage and printing firms who were given such information in order to provide services to the corporation whose securities they traded; government employees who learned of such information because of their employment by the government; and other persons who misappropriated, and took advantage of, confidential information from their employers.