Legal Commentary

Ninth Circuit on Medical Evidence

By David Bernstein

In the recent case of Primiano v. Cook, Ninth Circuit reversed the district court?s exclusion of a physician?s expert testimony on the failure of an elbow prosthesis.

The plaintiff?s expert, Dr. Weiss, testified

that the polyethylene bushing had worn through in less than eight months, ?not a usual or expected circumstance.? Though finite, the typical lifespan of elbow prostheses ?far exceeds? how long this one lasted. Dr. Weiss testified in his deposition that although wear starts immediately, elbow prostheses last as long as ten or fifteen years, even twenty, and the earliest he had seen them wear out was around five to eight years, varying with the patient?s activity level.

Dr. Weiss did not, however, know why the device failed.

The district court had excluded the testimony, on the theory that the mere fact that the device failed early cannot support an inference of defect; the real problem may have been that the device was inserted improperly by the plaintiff?s physician, who was also a defendant in the case.

If I were the district judge, I would probably have let Weiss?s testimony in, though I disagree with the Ninth Circuit that the judge abused his discretion in excluding it.

But what really disturbs me about the Ninth Circuit?s opinion is that it contains a great deal of loose language suggesting that Rule 702?s requirements that expert testimony testimony be ?based upon sufficient facts or data,? ?is the product of reliable principles and methods,? and ?the witness has applied the principles and methods reliably to the facts of the case? can be met by bringing in a medical expert who relies on his ?experience,? even if his testimony amounts to speculation based on very limited information. (The court engages in a typical subterfuge: instead of explaining how its view of medical testimony fits the rather clear language of Rule 702, it cites that language but focuses on precedents, including precedents from before the rule was amended. The court also to some degree conflates the issue of qualifications, itself often a problem for medical experts, with the issue of whether the expert is providing competent testimony under Rule 702).

It?s true that physicians often operate in a world of uncertainty, where no sound underlying scientific literature exists, and essentially have to make their ?best guess? as to what?s good for their patients. But physicians treating their patients are in a very different position than physician who are testifying in court. The former are being paid to help their patients get well; the latter are being paid to say things that will be helpful to a party in litigation. Given the hundreds of thousands of physicians available as potential experts, who have a wide range of views, and some of whom are willing to serve as hired guns, if courts simply let medical experts testify to various theories of causation on their own say-so, at best juries will always be confronted with conflicting speculation that is impossible to penetrate, and at worst junk science will reign supreme.

Full post as published by The Volokh Conspiracy on March 21, 2010 (boomark / email).