After some decades an event on my research area was announced in my city, so I decided to send my abstract, which was accepted.
However, they recently sent me the programme and among the keynote speakers was a person whose doctoral thesis contains uncontroversial plagiarism. (About 30 pages of his thesis are just a translation from two papers written in English by other scholars into the language in which the thesis was written.) There are no legal charges against this lecturer. Instead, the plagiarism was revealed by an apparently anonymous source about two or three years ago through a mailing list.
I know that at least some of the organisers of the event were in such mailing list, so they do not ignore the charges and had the chance to test whether they were true or not.
I have considered that maybe the best option to withdraw my lecture from the event explaining exactly why to the organisers. This, though, would not help at all, since they already know and do not care. Else they wouldn't have invited him as keynote speaker.
Other option that somebody suggested me is that I use some minutes of my lecture to publicly denounce him. (It just happens that my regular lecture starts right after his keynote lecture finishes.) But there are three problems with this:
When publicly denounced, this lecturer threatened to prosecute the source for defamation. (He's also lawyer.) I currently do not have a job nor a regular income that would allow me to face a prosecution, let alone to prosecute him.
It is very likely that most of the people that are going to the event already know. In such case, and since this is fairly yesterday news, I do not expect that there be any important reaction.
I am about to enter in the phase of defending my thesis, and this lecturer works in my institution as invited professor. Unscrupulous as he is, he may try to retaliate against me by using his power to delay my thesis dissertation. (I do not know how much power he has.)
Finally, you may be surprised as to how a whole academic community could care so little about this case. But I have to say that when the news about his plagiarism came, I myself didn't dare to publicly speak disapproving his behaviour because of what I said in the third point. Still, it was surprising to me that, although I know that several professors disapproved of his actions, apparently none of them publicly manifested their disapproval. I later knew that this wasn't the first time that something like this happens in my institution.
I'd like to know what is the most ethical or less unethical thing to do in this case. One thing is for sure, though. I do not think it would be right for me to go to that event, and speak after him as if he were a respectful scholar. And I am not going to.
Thanks in advance for any advice.