When Wesley Smith writes that “Scientists who want to testify in favor of a ban on human cloning are warned that if they do, their careers are over,” Andrew Stuttaford replies, “Oh really? Well, who are these guys then?”

Andrew, please do think again.

The kind of intimidation that concerns Smith is so dangerous precisely because it involves a “chilling effect” (a term used often in First Amendment jurisprudence) that makes it impossible to identify every instance of censorship, or, rather, of self-censorship—of silence. Laws or “speech codes” disputed on First Amendment grounds may therefore be challenged on their very faces, without any showing of actual damage. The absence of a long list of scientists who have been the victims of intimidation proves nothing.