There's an interesting, though perhaps slightly obscure, Guardian column on the notion of expertise in bioethics here. The author, Nathan Emmerich, suggests that we should be wary of making professional bioethicists into a 'priestly caste'. I'd suggest that professional bioethicists may be better than priests, but I think he has a point about moral knowledge/expertise and deference.
The moral or political philosopher doesn't have the kind of expertise that delivers answers that others must simply defer to. I frequently stress to my students that an argument from authority is worthless and that they need to assess what they read critically. Does this mean that there is no such thing as moral expertise? Well, not exactly - it all depends what you mean by 'expertise'.
All of us are capable of thinking deeply and careful about important moral questions. Those who research, or have studied, moral philosophy have an advantage in that they have spent more time than most engaged in such reflection and will presumably be familiar with certain argumentative moves (e.g. slippery slopes) and common fallacies. Thus, we might hope, they will be less likely to reach the conclusions that they do on the basis of bad reasoning and so, hopefully, less likely to reach bad conclusions.
To the worry that relying on moral experts is undemocratic, I think the appropriate response is the broadly Millian one, that the value of free speech is that it allows bad arguments to be confronted by better ones. Experts shouldn't be able to silence ordinary people in virtue of their expertise - our basis for trust in their judgements should rest on the fact that they cannot be defeated by opposing arguments. (There is, of course, a problem here is saying who wins an argument; the quality of public debate is often lamentably poor.)
I don't think that anything I say here challenges Emmerich's position. He concludes "Expert bioethicists cannot allow themselves to become a priestly caste. They must engage with the public and, in doing so, become more fully engaged by and with their concerns", which is not to say that there is no expertise in bioethics, but only that expert bioethicists must engage with the public. That's something I wholeheartedly agree with and one of the purposes of this blog, to facilitate engagement and exchange of view.
David Hunter has his own response to Emmerich on the BMJ blog.