Abstract
I. Introduction Jeremy Bentham's memorable description of "Injustice and her handmaid, Falsehood" 2 should remind us, if we need reminding, that factual truth is an important element of justice, 3 that it really matters whether this witness's recovered memory of an alleged crime is genuine, whether this is the person who committed the crime, whether this plaintiff's injury was caused by a defect in this manufacturer's tire or seat-belt buckle or lawn-chair, whether this was the chemical exposure that caused or promoted the plaintiff's cancer, and so on. 4 Because the factual truths at issue in a case often go beyond what the average juror can be expected to know, courts have come increasingly to rely on expert witnesses, among them scientists testifying on just about every subject imaginable: experts on blood, bullets, bite-marks, battered wives; on PCBs, paternity, poisons, post-traumatic stress; on radon, recovered memories, rape trauma syndrome, random-match probabilities; on psychosis, asbestosis, silicosis (and for all I know, on psittacosis!). But as long as courts have relied significantly on scientific witnesses, there have been complaints: about the scientific ignorance and gullibility of attorneys, judges, and jurors; about "witness-shopping"; and - as my opening quotation illustrates - about the irresponsibility and venality of professional scientific experts willing to say whatever is needed to advance the cause of the party that hires them. As reliance on expert witnesses has grown, so has the felt need for courts to ensure that the expert testimony admitted is not just flimsy or ...