Every jurisdiction has strict requirements for what qualifies as an expert. Often times publishing requirements will be cited, but recognition among peers is usually a basic necessity.
Hmmm. My understanding is slightly different; what qualifies as an expert is decided on a case-by-case basis during
voir dire. Part of the reason for this is that many types of "expertise" do not have corresponding formal study or credentials -- e.g., a footprint expert didn't major in the footprintology program at Harvard and hasn't published in the American Journal of Footprints, because neither of those exist. So you can be the most far-out lunatic in the asylum as long as you can talk a good enough line to fool the judge into signing off on your expertise.
.... which, of course, opposing counsel will work
hard to prevent.
Kitzmiller provides an instructive example; Barbara Forrest was called as an expert on the history and philosophy of creationism. Of course, this isn't a recognized field (and she's actually a professor of philosophy more generally), but the defense recognized that if she was able to testify,
as an expert, that ID was really just creationism, that would harm their case a lot.
Now, of course, Dr. Forrest is a genuine expert, and was able to produce hectares of papers that she had authored on this subject, so she had only minor trouble with the voir dire. Oddly enough, "recognition among peers" never came up (probably because counsel recognized that as a losing card to play on a tenured professor).
It's a contentious issue and many times opposing attorneys will challenge the credentials of expert witnesses.
Absolutely. And justifiably so.
There's
an interesting web site here that defines the "ideal" qualifications for an expert to have (at least in one lawyer's opinion), and it definitely includes being a professional in a strict sense. Someone who refrobnitzes bellaria for a living is going to be a much more credible witness on the subject of refrobnitzing bellaria -- "A practitioner expert witness can look the jurors in the eye and confidently assure them that his or her opinions are correct. This confidence stems from the fact that the practitioner expert successfully performs the questioned procedure on a regular basis. An expert witness who has little or no hands-on experience can be vulnerable to cross examination, even if the expert has an impressive curriculum vitae. An expert witness with practitioner experience, on the other hand, can quiet critics, whether they are judge, jury, or opposing counsel contending that the expert is merely restating opinions he has only read about. Quite simply, there is no substitute for doing."