“Dummkopf! You’re Fired” – Judge Posner on Expert Witness Gatekeeping

“Equity is a roguish thing, for law we have a measure, know what to trust to. equity is according to the conscience of him that is chancellor, and as that is larger or narrower so is equity. ’Tis all one as if they should make the standard for the measure we call a foot, a chancellor’s foot. What an uncertain measure would this be. One chancellor has a long foot, another a short foot, a third an indifferent foot; ’tis the same thing in the chancellor’s conscience.”

John Selden, The Table Talk of John Selden (1689), at 61 (Samuel Harvey Reynolds, ed., Oxford 1892).

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As Equity in days of old varied with the size of the Chancelor’s foot, today the quality of judicial gatekeeping of expert witness opinion testimony varies with the acumen of the trial judge in the area of the challenged witness’s expertise.  In Apple Inc. v. Motorola, Inc., 2012 WL 1959560 (N.D. Ill. 2012), the parties challenged each other’s damages expert witnesses under Federal Rule 702, only to find that the trial judge was considerably more astute than their expert witnesses. When it came to assessing the validity and reliability of the damages opinions, the trial judge was a veritable “big foot,” kicking the courthouse door closed to some dodgy damage calculations.

The Hon. Richard Posner is a judge of the United States Court of Appeals, for the Seventh Circuit.  Judge Posner is also an economist and a stalwart of law-and-economics jurisprudence. In Apple v. Motorola, Judge Posner sat by designation as a trial judge.   Instead of judging whether a trial judge had abused his or her discretion in admitting or excluding expert witness testimony, Judge Posner had to put his own discretion on the line. 

Judge Posner identified the biggest challenge in gatekeeping as:

“distinguish[ing] between disabling problems with the proposed testimony, which are a ground for excluding it, and weaknesses in the testimony, which are properly resolved at the trial itself on the basis of evidence and crossexamination.”

Apple Inc. v. Motorola, Inc., 2012 WL 1959560, *1. Posner cites old caselaw, arguably superseded by the current Rule 702, for the chestnut that:

“the judge should not exclude evidence simply because he or she thinks that there is a flaw in the expert’s investigative process which renders the expert’s conclusions incorrect. The judge should only exclude the evidence if the flaw is large enough that the expert lacks ‘good grounds’ for his or her conclusions.”

Id. (quoting In re Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 746 (3d Cir.1994)). Of course, flawed reasoning or methodology is the essence of what deprives anyone from making an claim to knowledge; this little chestnut is not very nourishing.

Judge Posner does better in “operationalizing” Kumho Tire for making the distinction between flaws that weaken, and those that vitiate, the epistemic bases for opinions.  Whether an expert witness “employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field” is a key test for determining on which side of the distinction a challenged opinion falls. Id. at *2 (quoting Kumho Tire Co. v. Carmichael, 526 U.S. 137, 152 (1999)).

“The Kumho principle implies that an expert witness must provide reasons for rejecting alternative hypotheses ‘using scientific methods and procedure’ and the elimination of those hypotheses must be founded on more than ‘subjective beliefs or unsupported speculation, … .’ ”

Id. at *8 (internal citations omitted).

Posner tempers, and dilutes, Kumho by qualifying the Kumho principle to require a testifying expert to use the same approach as used in the relevant field “if it is feasible for him to do so.” Id. at *3. It is always feasible, but rarely seen, for an expert witness to profess insufficient knowledge, facts, or data to give an opinion. Posner goes further and rewrites the statute, Rule 702, which was designed to keep uncertainty from being masqueraded as certainty:

“when the plaintiff has done his best to prove damages his inability to dispel uncertainty concerning the accuracy of his claim is not fatal. But if an expert witness fails to conduct a responsible inquiry that would have been feasible to conduct, his failure cannot be excused by reference to the principle that speculation is permitted in the calculation of damages; that permission presupposes the exhaustion of feasible means of dispelling uncertainty. Uncertainty is a bad; it is tolerated only when the cost of eliminating it would exceed the benefit.”

Id. at *5.  Sometimes the best efforts to eliminate uncertainty will leave us uncertain.  And the issue of acceptable uncertainty is not necessarily tied to the cost of eliminating it.

Nevertheless, Posner goes on to identify multiple unreasonable assumptions, alternative inferences, missing data, and flawed methods that vitiated most of the opinions before him in Apple v. Motorola.

Judge Posner applies the Kumho principle in the context of damages with a series of counterfactual Gedanken experiments.  He asks what if the plaintiff’s expert witness were working for the defendant (and vice versa), and charged with ascertaining the lowest cost to avoid infringing the plaintiff’s patent.  If the expert submitted the most expensive approach, or an extremely speculative, answer, the defendant would indeed fire the expert: “Dummkopf! You’re fired.” Id. at *9. And if the expert offered unverified evidence that came from an interested, adverse party, the expert’s opinion would again be worthy of no consideration.

Judge Posner is at home in the world of assessing economic damages, and as a “Chancellor,” he proved to have a very big foot indeed. The parties’ expert witnesses came up short on almost every damages opinion examined.

Not all evidentiary issues can be resolved by Judge Posner’s economic reductionism as neatly as the damages issues in this patent infringement case.  Posner’s approach is less satisfying in the context of health effects litigation, where expert witnesses will often have the option of proclaiming inadequate knowledge or method to ascertain general or specific causation.  Still Posner’s Gedanken experiments are contagious.  Suppose we were confronted with a birth defect case in which plaintiffs claimed that the mother’s use of a medication in early pregnancy caused the child’s birth defect.  It is generally conceded that most such birth defects have no known cause, but the plaintiffs’ expert witnesses contend that they have conducted a differential etiology and ascribed causation of the baby’s defect to the mother’s use of the defendant’s   medication.  Suppose there was a serious economic (or life-and-death) consequence to the expert’s opinion.  If the defect were drug-induced, there was no surgical or other correction, but if the defect were “idiopathic,” it could be readily repaired surgically.  Would the expert witness, acting as a treating physician, withhold the treatment because he was “reasonably medically certain” that the defect was caused by the drug?  I don’t think so.  Dr. Dummkopf, you’re fired!

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