A hypothetical: You are a journalist who has written a great deal about the anti-vaccine movement and you have been asked to participate in a panel on the safety of childhood vaccines. This panel was organized by professional medical and health journalists. Also on this hypothetical panel would be a prominent scientist, such as Paul Offit, who has authored numerous books rebutting myths and misinformation about vaccines (and more recently, alternative medicine practices). The third panelist would be a persistent anti-vaccine activist, perhaps someone from the group Age of Autism. I'm guessing that Paul Offit and the science journalist (say, Seth Mnookin) would not want this panel to be derailed or hijacked by an anti-vaccine activist spouting loads of misinformation. For this reason, maybe they would decline to participate in such a forum. I'm only speculating. I raise this hypothetical because I just turned down an opportunity to participate in an upcoming panel on GMOs. The organizer initially asked if I would moderate a panel that included scientists and advocates "pro- and con-GMO." I expressed interest after hearing that the objective was "to foster a lively and factual discussion on GMO's with a well-rounded panel." And then I learned that Jeffrey Smith was one of the invited panelists. Just to be clear: I am in favor of a robust discussion on any topic, especially one with a diversity of perspectives. (For the anti-GMO side, I suggested the organizer invite representatives from the Union of Concerned Scientists.) But I don't think that someone with fringe views and assertions wholly unsupported by science can help "foster a lively and factual discussion on GMOs." And make no mistake, Smith is as fringe as they come. As I have previously discussed here, he has asserted that autism and Alzheimer's disease, among many other medical problems, can be attributed to GMOs. Did I mention that he has no expertise? That Smith has become a go-to person for the anti-GMO movement speaks as much to his marketing skills as it does to the kind of forums he is regularly invited to and the lack of vetting by those (who should know better) who invite him to participate in otherwise well-meaning events. It's unfortunate (but not surprising) that Dr Oz has irresponsibly given Smith a huge forum (twice!). Science-minded organizers who confer legitimacy on Smith with speaking invitations should ask themselves if they would similarly invite anti-vaccine cranks to expound on the health and safety of vaccines.