Admission/exclusion of expert testimony and the “abuse of discretion” standard of review

As every trial lawyer knows, the admissibility of a vast array of evidence is committed to the trial court’s discretion.  (Or “sound discretion,” as some appellate courts put it, though as far as I can tell it means the same thing.)  Consequently, one of the unavoidably nerve-wracking aspects of litigation is that Judge A and Judge B might reach opposite conclusions on the admissibility of the same evidence, yet both rulings could be upheld on appeal because neither ruling was an abuse of discretion.  So, without in any way denigrating the importance of our skill and experience in trial advocacy¹, a lot depends on the luck of the draw, i.e., whether Judge A or Judge B is trying the case.  That is also something every trial lawyer knows.

There are two kinds of evidence.  The admissibility of one kind is a pure question of law.  For example, testimony covered by a privilege (spousal, attorney-client, priest-penitent) is inadmissible, period.  If a privilege is asserted and the testimony is admitted over objection, the appellate court will decide whether the trial court committed an error of law in determining that the claimed privilege either did not apply under the particular facts of the case or was waived.  Questions of law are reviewed de novo – the appellate court owes the trial court no deference. 

The admissibility of the other kind of evidence depends on weighing a variety of factors.  For example, Fed. R. Evid. 403 provides: “The court may exclude relevant evidence if its probative value is substantially outweighed by a danger of one or more of the following: unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.”  When a trial court admits or excludes relevant evidence based on these considerations, the question on appeal is not whether the evidentiary ruling was an error of law, but whether it was an error of judgment, which is a very different matter.  Here the review is for abuse of discretion, the most deferential standard:  “[R]eversal under [the] abuse of discretion standard is possible only when the appellate court is convinced firmly that the reviewed decision lies beyond the pale of reasonable justification under the circumstances.  The abuse of discretion standard requires an appellate court to uphold a district court determination that falls within a broad range of permissible conclusions.” (internal quotation marks omitted; emphasis added).

In Marquardt v. Schaffhausen,, a recent decision upholding the admission of medical expert testimony, the Minnesota Supreme Court explained in more detail how the abuse of discretion standard operates:

We review the district court’s decision to admit expert testimony for an abuse of discretion.  Generally, the exclusion of expert medical testimony lies within the sound discretion of the trial court, and its ruling will not be reversed unless it is based on an erroneous view of the law or it constitutes an abuse of discretion.  When exercising its discretion, the district court has wide latitude in determining whether there is sufficient foundation upon which an expert may state an opinion.  And we apply a very deferential standard to the district court when reviewing a determination as to expert qualification.  [We will not] reverse even if we would reach a different conclusion with respect to the sufficiency of the foundation.  These determinations demand a case by case analysis that is best left to the trial judge familiar with the setting of the case.  (Citations and internal quotation marks omitted.)

The plaintiff in Marquardt had a knee replacement performed by the defendant orthopedic surgeon.  Upon opening the joint, the surgeon observed dark, cloudy fluid and necrotic tissue.  He cultured the material and also ordered a Gram stain test.  The former takes 24 hours to produce results; the latter came back negative while the patient was still on the operating table, so the defendant elected to proceed with the surgery.  The next day, one of the cultures grew out MRSA.  This was initially treated with IV vancomycin, which had to be stopped when the plaintiff suffered renal failure due to vancomycin toxicity; other antibiotics were substituted.  Over the next several weeks the plaintiff had seizures and was in and out of the hospital.  An MRI showed evidence of brain injury and the plaintiff had symptoms of brain damage, including vision changes and confusion.  She eventually recovered but has permanent neurological deficits, including significant impairment of spatial awareness, loss of depth perception, and short-term memory loss. 

The plaintiff’s theory of causation was that the surgery allowed the MRSA bacteria to enter her bloodstream and spread to her brain, resulting in a form of encephalitis (ADEM) that caused the brain damage.  The defendant’s opposing theory was that the culprit was the vancomycin toxicity, which caused a completely different brain-damaging syndrome (PRES).  If the defendant had delayed the surgery pending the culture results, the plaintiff would have been treated with vancomycin when the MRSA infection was revealed, and hence would have developed vancomycin toxicity and PRES even if surgery had not been performed; therefore, the decision to proceed with the surgery did not cause the brain damage.  (I’m not getting into a technical explanation of ADEM and PRES. If you’re interested in the details, the opinion is worth reading.)

At trial the plaintiff presented the video depositions of two medical experts:  Dr. Stark, a general orthopedic surgeon, and Dr. Stephan, an infectious diseases specialist.  The depositions were admitted over the objection of the defendant, who argued that the doctors were not qualified to opine on causation.  “The district court explained that Dr. Stark and Dr. Stephan did not need to be neurologists to give opinions on the causation of Marquardt’s injuries…[and the defendant’s] objection went to the weight of the opinions rather than their admissibility.”  The jury returned a verdict for the plaintiff, and the defendant appealed.  “A divided panel of the [intermediate] court of appeals reversed….The court of appeals determined that Dr. Stark and Dr. Stephan were not qualified to testify as to causation because they lacked the requisite occupation experience in neurology, ADEM, and PRES.” 

The supreme court reversed the decision of the intermediate court.  In its short discussion of the experts’ qualifications, the court noted that Dr. Stark had experience performing knee replacements and had “practical experience with surgery related-infections and extensive training in recognition and response to infections that arise during surgery,” including MRSA infections of spinal hardware.  (Internal quotation marks omitted.)  Dr. Stephan, the infectious diseases specialist, had “much experience with MRSA infections…[including] experience treating patients with MRSA-infected prosthetic knee joints.”

In short, both experts Marquardt proffered have sufficient training and experience for the district court to conclude, within its broad discretion, that they were qualified to opine on causation.  As the dissent in the court of appeals noted, the causation issue in this case was not simply whether Marquardt had ADEM or PRES.  Broadly defined, the causation issue was whether the knee-replacement surgery caused the spread of MRSA and whether the spread of MRSA ultimately led to Marquardt’s injuries.  It was not an abuse of discretion for the district court to conclude that these doctors could opine on that broad causation question, even if they may not be qualified to testify as to the narrower question of ADEM versus PRES

The district court has an important gate-keeper role when determining whether to admit expert testimony.  The district court properly performed that role here, carefully weighing the qualifications of the experts before deciding to admit their testimony.  The district court acknowledged that the question of admissibility was “close.”  And the fact that other district courts might have made a different decision on that question does not make the district court’s decision an abuse of discretion.  On this record, we cannot conclude that the district court abused its discretion when it determined that Dr. Stark and Dr. Stephan were competent to testify as to causation.  (Citations omitted; emphasis added.)

The court is plainly stating that the admissibility of the experts’ testimony was a close question, that it could have gone the other way, and that a decision the other way also would not have been an abuse of the trial court’s discretion.  Which brings me back to Judges A and B, who I started out with.  You want to avoid a close question of admissibility – to maximize the probability that both Judge A and Judge B, regardless of their general attitude towards expert testimony, will exercise their discretion to admit the testimony of your experts.  To do that, you need precisely the right expert for each case.  In Marquardt, although a general orthopedic surgeon passed muster (barely), the ideal expert would have been a specialist in hip and knee replacement (also known as adult reconstruction), who would have had specific expertise in the diagnosis and treatment of infected knee joints and knee prostheses.  I don’t know why the plaintiff’s team of experts didn’t include a neurologist, but if it had, the defendant would have had no argument whatsoever on the admissibility of causation testimony, and a costly and time-consuming appeal might have been avoided. 

At Vident Partners, our goal is always to provide you with the ideal expert for each case.  We look forward to working with you.


¹I’m allowed to say “our” because I was a trial lawyer for 15 years, back when dinosaurs roamed the earth. 


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