Experts Who Cannot Articulate a Standard Cannot Opine that a Defendant Failed to Meet the Standard

If you don’t know where a line is, you can’t say whether someone has crossed it. That principle applies in spades to expert witnesses, particularly when their role in the case calls on them to help the jury understand where the lines are drawn in their field. Thus, for example, a toxicology expert who cannot say how much chemical exposure is required to produce a toxic effect cannot opine that the plaintiff’s exposure was sufficient to cause that effect. Likewise, an expert who criticizes a…
By: Faegre Drinker Biddle & Reath LLP