Diluting “Reasonable Degree of Medical Certainty” – An AAJ-Restatement “Tool” to Help Plaintiffs

In “the Top Reason that the ALI’s Restatement of Torts Should Steer Clear of Partisan Conflicts,” I pointed out the inappropriateness of advertising the ALI’s Restatement of Torts to the organized plaintiffs’ bar, much as the plaintiffs’ bar advertises potential huge recoveries for the latest tort du jour.  See Michael D. Green & Larry S. Stewart, “The New Restatement’s Top 10 Tort Tools,” Trial 44 (April 2010).

Some of the authors’ tort tool kit may be unexceptionable.  Among these authors’ top ten tort tools, however, is the new Restatement’s edict that “reasonable degree of medical certainty” means, or should mean, nothing more than saying “more likely than not.”  The authors criticize the reasonable certainty standard with an abbreviated rendition of the Restatement’s critique:

“Many courts hold that expert opinion must be expressed in terms of medical or scientific certainty’. Requiring certainty seems to impose a criminal law-like burden of proof that is inconsistent with civil burdens of preponderance of the evidence to establish a fact. Such a requirement is also problematic at best because medical and scientific communities have no such ‘reasonable certainty’ standard. The standard then becomes whatever the attorney who hired the expert tells the expert it means or, absent that, whatever the expert imagines it means. Section 28, comment e, of the Restatement criticizes this standard and makes clear that the same preponderance standard (or ‘more likely than not’ standard), which is universally applied in all aspects of civil cases, also applies to expert testimony.”

Id. at 46-47.

Well, the more likely than not standard is not “universally applied in all aspects of civil cases,” because several states require exemplary damages to be proven by “clear and convincing” or greater evidence.  In some states, the burden of proof in fraud cases is higher than a mere preponderance of the evidence. This premise of the authors’ article is incorrect.

But even if the authors were correct that the preponderance standard applied “in all aspects” of civil cases, their scholarship would remain suspect, as others and I have previously pointed out.  SeeReasonable Degree of Medical Certainty,” and “More Uncertainty About Reasonable Degree of Medical Certainty.”

1. The Restatement’s Treatment of Expert Witness Evidentiary Rules Exceeded the Scope of the Tort Restatement.

The most peculiar aspect of this “top tool,” is that it has nothing to do with the law of torts.  The level of certitude required of an expert witness is an evidentiary and a procedural issue. Of course the issue comes up in tort cases, which frequently involve medical and scientific causation opinions, as well as other expert witness opinions.  The issue, however, comes up in all cases that involve expert witnesses:  trust and estates, regulatory, environmental, securities fraud, commercial, and other cases.

The Restatement of Torts weakly acknowledges its frolic and detour in treating a procedural issue concerning the admissibility of expert witness opinion testimony, by noting that it does “not address any other requirements for the admissibility of an expert witness’s testimony, including qualifications, expertise, investigation, methodology, or reasoning.” Restatement (Third) of Torts: Liability for Physical and Emotional Harm § 28, cmt. e (2010).  The certitude issue has nothing special to do with the substantive law of torts, and should not have been addressed in the torts restatement.

2. The Restatement’s Treatment of “Reasonable Degree of Medical Certainty” Has No Relevance to the Burden of Proof in Tort Cases.

The expert witness certitude issue has nothing to do with the burden of proof, and the Restatement should not have confused and conflated the burden of proof with the standard of certitude for expert witnesses.  The clear but unacceptable implication is that expert witnesses in criminal cases must testify to certitude “beyond a reasonable doubt,” and in claims for equitable relief, expert witnesses may share only opinions that are made, in their minds, by “clear and convincing evidence.”  There is no support in law or logic for the identification of witness certitude with parties’ burdens of proof.

Comment e states the critique more fully:

“If courts do interpret the reasonable-certainty standard to require a level of certitude greater than the preponderance-of-the-evidence standard requires, this creates a troubling inconsistency between standards for the admissibility of evidence and the threshold required for sufficiency of proof. The threshold for admissibility should not be higher than the threshold to sufficiency.  Moreover, the reasonable-certainty standard provides no assurance of the quality of the expert’s qualifications, expertise, investigation, methodology, or reasoning.  Thus, the Section adopts the same preponderance standard that is universally adopted in civil cases.  Direct and cross-examination can be employed to flesh out the degree of certainty with which an expert’s opinion is held and to identify opinions that are speculative and therefore inadmissible.”

Id. The critique badly misfires because there is no inconsistency and no trouble in having different standards for the admissibility of opinion evidence and the burden of proof.  As noted, expert witnesses testify on causation and other issues in criminal, equity, and tort cases, all with different burdens of proof.  Juries in criminal and tort cases must apply instructions on burdens of proof to an entire evidentiary display, not just the expert witnesses’ opinions.  In logic and law, there ultimately must be different burdens for admissibility of expert witness testimony and for sufficiency of a party’s proofs.

3. The Restatement’s Treatment of “Reasonable Degree of Medical Certainty” Incoherently Confuses Two Different Standards.

We can see that Comment e’s approach to legislating an equivalence between expert witness certitude and the burden must fail even on its own terms.  Consider the legal consequences of tort claimants, with the burden of proof, who produce expert witnesses to opine about key elements (e.g., causation) of torts by stating that their opinions were held by a mere “preponderance of the evidence.”

If this probability is understood to be only infinitesimally greater than 50%, then courts would have to direct verdicts in many (and perhaps most) cases.

Courts must ensure that a rational jury can find for the party with the burden of proof.  Juries must evaluate the credibility and reliability of expert witnesses, their opinions, as well as the predicate facts for those opinions.  If those expert witness opinions were barely greater than 50% probable on an essential element, then unless the witnesses had perfect credibility, and all predicate facts were as probable as claimed by the witnesses, then juries would frequently have to reject the witnesses’ opinions.  The bare preponderance of the expert witnesses’ opinions would result in an overall probability of the essential element less than 50%.

4. The Restatement Incorrectly Implies that Expert Witnesses Can Quantify Their Opinions in Probabilistic Terms.

There are even more far-reaching problems with simply substituting “more likely than not” for RDMC as a threshold requirement of expert witness testimony.  Comment e implies that expert witnesses can discern the difference between an opinion that they believe is “more likely than not” and another which is “as likely as not.” On some occasions, there may be opinions that derive from quantitative reasoning, for which an expert witness could truly say, with some level of certainty, that his or her opinion is “more likely than not.” On most occasions, an expert witness’s degree of certainty is a qualitative opinion that simply does not admit of a quantitative characterization. The Restatement’s comment perpetuates this confusion by casting the reasonable certainty standard as a bare probability.

Comment e further suggests that expert witnesses are themselves expert in assessing their own level of certainty, and that they have the training and experience to distinguish an opinion that is 50.1% likely from another that is only 50% likely. The assignment of precise mathematical probabilities to personal, subjective beliefs is a doubtful exercise, at best. See, e.g., Daniel Kahneman and Amos Tversky, “Judgment under Uncertainty: Heuristics and Biases,” 185 Science 1124 (1974).

5. The Restatement Incorrectly Labels “Reasonable Degree of Medical Certainty” As An Empty Formalism.

Comment e ignores the epistemic content of reasonable certainty, which bears an uncanny resemblance to the knowledge requirement of Rule 702.  The “mantra” is helpful to the extent it imposes an objective epistemic standard, especially in states that have failed to impose, or that have abrogated, expert witness gatekeeping.  In some states, there is no meaningful expert witness gatekeeping under either the Frye standard or Rule 702. See, e.g., “Expert Evidence Free-for-All in Washington State.”  See also Joseph Sanders, “Science, Law, and the Expert Witness,” 72 Law & Contemporary Problems 63, 87 & n. 118 (2009) (noting that the meaning of “reasonable degree of scientific certainty” is unclear, but that it can be understood as an alternative formulation of Kumho’s “same intellectual rigor” test).

Some of these “top” tools may be defective.  The authors may need good defense counsel.

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