None supported the idea that PCBs cause cancer in adult men. Joiner was a dead duck. Under Dauber, the experts had to convince the judge that their principles and methods were valid. The experts could not tie the chemicals, the mice and the epidemiological studies closely enough to Joiner. As a result, the experts never took the stand.
New rules apply only in federal courts.
Many states, however, copy federal rules of evidence all but verbatim. Gradually, courts will treat expertise far more cautiously than in the past. Judges have a powerful new tool to combat junk science.