First, I'd like to say that I HATE this term, since it's most often been used to cheaply smear and denigrate actual, very solid science that just happened to refute whatever greedy and/or dishonest position that a given environmentally-unfriendly corporation or wackjob religious organization was trying to promote (e.g. excess carbon is "good" for the environment because it makes things "grow", creationism is a valid explanation of the origins of life, etc.). Used in this sense--which of course is how it's most often used--it is an unethical and dishonest propagandistic tool used to score cheap political points among uninformed people.

Read this, from one of my favorite groups, the Innocence Project:

Forensic science errors are a leading cause of wrongful convictions nationwide. Scientific errors, fraud or limitations were a factor in 63% of the first 86 DNA exoneration cases, according to an August 2005 analysis of the cases published in Science magazine. These forensic science mishaps include everything from lab analysts who committed fraud to expert witnesses who relied on analyses of forensic disciplines which have never been adequately validated to identify a perpetrator such as: hair, bullets, handwriting, footprints, or bite marks. Using DNA – which provides a precise identification that other methods cannot – wrongful convictions were exposed years or even decades later.

Rest here: http://www.innocenceproject.org/Content/394.php

I can't easily find the link, but one of these forensic "bite mark" scientists was recently sent to prison for fraud- after her testimony sent a scad of folk to prison.

And that is just on the criminal end, not civil.

My entire point was that in our legal system, in civil suits it is entirely the claimant's responsibility, not the courts', to demonstrate that the plaintiff's expert technical witnesses are in fact making fraudulant and/or unsound claims.

That is exactly wrong. It is up to judges to decide what "scientist" is competent to give expert scientific testimony. The track record there has been abysmal, not just for civil litigants, but also for people sent to prison on criminal charges. Judges are not gods, you know. Do you not expect science to police itself to some degree and make a fuss about this wretched state of affairs?

High-powered lawfirms for the plaintiff's bar, expecting a third of the recovery on a multi-million $ suit, are very good at getting crackpot science admitted. They put these "scientists" through mock cross-examination until they can spin bullshit that mesmerizes a jury.

But if you think our court system has been perfect, and that a lot of judges have not let nonsensical "experts" testify, well, I don't know what more to say.

I still think that on the issue of global warming, at least, [Cato] are acting exactly like a right-wing propaganda organ.

Why you think that I do understand, but their reasons are different. I came of age when Paul Ehrlich and other scientists were all being heralded as knowing a population bomb was about to destroy the planet by 1980. Famines and mineral depletion by 1990. That a global ice age was upon us due to pollution. We libertarians grew skeptical of politicized science.

Global warming, as it turns out, is real. But to what extent, and how severely we should employ govt to restrain choices, is still an issue. Cato just doesn't want to let the same statists who feverishly warned of prior non-emergencies to set an overly statist and anti-liberty solution. They are looking for neutral evaluations and reasonable solutions.

Under what legal rule or precedent can a judge rightfully exclude a given scientist's testimony on their own, absent legitimate objections by the other side's lawyers?

Obviously the other side must object. But once they do, then what, should the "scientist" be allowed to tell the jury it's a fact that chlorophyll kills people and all landscapers and seed sellers are merchants of death? If 99.99% of scientist say that is horseshit, should the jury weight equally that one "expert," and the opposing expert testifying for the other side and all the legions of scientists behind him who says the seed seller is not peddling a toxin? Should the first "scientist's" BS even be allowed as "expert" testimony if virtually 99% of the rest of scientists think it is crap on stilts? Or is expert testimony to mean nothing but a battle of whose lawyer can get the nuttiest crap in?

Do we let the "lone genius" concept corrupt every trial where scientific expertise is an issue?

And I continue to find it perplexing that it is you who is making the clearly anti-libertarian argument here, because I'm clearly the one making the libertarian one.

What you seem to not understand is that the scientific "expert" is allowed to state facts based in his or her so-called expertise. It is what makes them different from a "fact" (regular) witness testifying only about on-the-ground matters in the case at hand.

If the court promiscuously lets expert witnesses testify regardless of any bona fides, facts get lost as mattering. Courts must maintain some rigid controls on who gets to relate theory-laden testimony, or justice (and science as its tool) dies.

Yes, according to some, they should weight equally. But seriously, it is a rather disturbing issue, but as kovie argued before, it presents a problem form a libertarian point of view. How could you implement a rule that a lone scientist with a different opinion from 99.9% of his colleagues should not be allowed to testify?

Not for any of the libertarians I know. In a very rare case, the lone genius may be correct, but 99% of the time he or she is not. And someone whose life or liberty is at risk should not have to suffer testimony of, say, the random and isolated UC Berkeley prof who claims he is psychic and "knows" the guy did it. Not unless science as a community has via some peer review or other method lent some patina of credibility, should a person's life or liberty hang on such "expert" testimony.