In incidents of plagiarism, the accusers frequently have ulterior motives. The charges against Glenn Poshard at SIU were likely motivated by treatment handed out to a professor.
But it is not a defense to a charge of plagiarism to impugn the accuser..
Similarly, as to the Dr. Oz affair:
“It’s ironic that I’m being accused of conflict of interests by these doctors,” Oz declared, “when some of them…have their own conflicts of interest.”
Separately, as to. First Amendment issues, from a letter in USA Today:
Our governmental regulations regarding obscenity and commercial speech specifically state that radio and television receives "less than full protection" under the First Amendment. Stringent broadcast scrutiny with restrictions when necessary could be applied to protect public health against physician recommendations of treatments without clear disclosure regarding their possible side effects and true substantiated efficacy. An independent supervisory body functioning as an FDA regarding alternative medicine, similar to the German Commission E,would significantly curtail outrageous claims of miracle cures and would also support better utilization and understanding of alternative, non-western medicine by identifying the contexts in which it is effective scientifically rather than empirically.