Excluding Defense Expert Witness Reversible Error
“We review the district court's decision to exclude expert witness testimony for abuse of discretion.” FN32
[6] Sandoval-Mendoza wanted to present expert testimony concerning his mental condition and susceptibility to suggestion. He offered two expert witnesses: Dr. Michael Shore, a neuropsychologist, and Dr. J. Richard Mendius, a neurologist. The prosecutors also proposed expert witnesses: Dr. Ronald H. Roberts, a neuropsychologist, and Dr. Richard Cuneo, a neurologist. The district court held a DaubertFN33 hearing on whether any of these expert witnesses would be permitted to testify.
Defense witness Michael Shore, Ph.D., is a psychologist with extensive clinical and teaching experience in neuropsychology, focusing on the rehabilitation of patients suffering from brain damage caused by strokes, tumors, and other causes. He testified that Sandoval-Mendoza suffered from an unusually large pituitary tumor measuring 2 x 2 x 3 centimeters, about the size of an apricot, when diagnosed. The tumor compressed Sandoval-Mendoza's frontal lobe, temporal lobe, and thalamus, probably causing damage. Medication eventually shrank Sandoval-Mendoza's tumor to some degree, but could not reverse any brain damage.
The relationship between brain damage and cognitive impairment is well-documented. Tumors like Sandoval-Mendoza's may affect mental condition in two ways. First, damage to the pituitary gland may affect thyroid production, causing mood disorders, including depression. Second, direct damage to the frontal lobe, temporal lobe, and thalamus may affect memory, decision-making, judgment, mental flexibility, and overall intellectual capacity. In particular, damage to the frontal lobe often affects concentration, focus, learning, memory, decision-making, reasoning, judgment, and problem-solving, according to Dr. Shore.
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A battery of routine and widely-accepted tests showed Eduardo suffered from brain damage affecting his cognitive condition. Although an performance IQ test showed borderline mental retardation and a mental age of eleven, Dr. Shore concluded Sandoval-Mendoza's school and work history were not consistent with retardation, and attributed the test results to his tumor. A classic nineteenth-century study showed frontal lobe damage causes a person to have “the passions of a man but the mind of a child,” increasing suggestibility. In Sandoval-Mendoza's case, the brain damage apparently affected the “passions of a man” as well, because the tumor made him impotent.
Defense witness Dr. J. Richard Mendius, M.D., is a board-certified neurologist with additional expertise in clinical neurophysiology. He testified that a magnetic resonance imaging test showed Sandoval-Mendoza suffers from an unusually large pituitary tumor. When the tumor shrank after treatment, the frontal lobe herniated into the empty space. The tumor also caused atrophy of the inside of the left temporal lobe and penetrated a bone separating the pituitary gland from the brain stem. Brain damage of this kind tends to affect judgment, memory, and emotions connected to memory. A performance IQ test suggested a very low level of intellectual function. Both Shore and Mendius testified that they knew of no studies specifically linking brain damage of this kind with susceptibility to inducement to commit crimes. But they noted that it commonly causes disinhibition.
Prosecution witness Ronald H. Roberts, Ph.D., is a neuropsychologist who mainly testifies as an expert witness. Roberts agreed Sandoval-Mendoza suffered from an unusually large tumor. However, he believed Sandoval-Mendoza was deliberately under-performing on memory texts. He also believed the tumor did not significantly affect Sandoval-Mendoza's performance IQ test result. Though he did not contradict the determinations from the MRI films that Sandoval-Mendoza had an extremely large tumor, he gave the opinion that on the memory tests, Sandoval-Mendoza was faking a worse memory than he really had.
Prosecution witness Dr. Richard Cuneo, M.D., is a neurologist. Cuneo agreed Sandoval-Mendoza suffered from an unusually large pituitary tumor near areas of the brain controlling behavior and cognition. But medical understanding of behavior and cognition is preliminary and inconclusive. Dr. Cuneo thought the studies presented were inadequate to show that Sandoval-Mendoza's tumor and brain damage affected his behavior and cognition because the studies were retrospective and involve small samples. A patient of Dr. Cuneo's had a similar tumor that neither caused brain damage nor affected behavior and cognition. Sandoval-Mendoza's magnetic resonance imaging test did not show any brain damage, in Dr. Cuneo's opinion. While some brain tumors may cause disinhibition or greater susceptibility to influence, pituitary tumors do not, unless they are even larger than Sandoval-Mendoza's. Dr. Cuneo conceded that Sandoval-Mendoza's performance IQ test was borderline “retarded” and mentally retarded people are “known to be susceptible to the influence of others.”
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After the Daubert hearing, the district court excluded the expert testimony as “not relevant to the entrapment defense” because it “does not tend to show either inducement or a lack of predisposition attributable to the tumor.” The court based its ruling on the expert testimony's “lack of scientific validity” and “absence of ability to make a causal connection” between the tumor and inducement or predisposition. Alternatively, it concluded that the “probative value” of the expert testimony was “outweighed by the dangers of confusing the issues, misleading the jury, and creating undue delay,” and “would be extremely confusing to both the court and the jury” especially “given the fact that the defense witnesses will then be rebutted by government witnesses.”
As a consequence, only Sandoval-Mendoza himself, his ex-wife, and his sister could testify that his brain tumor made him forgetful and suggestible. The defense had another witness prepared to testify that Sandoval-Mendoza once drank his own urine sample, having forgotten what it was, but the witness disappeared after the prosecutor advised her that as an illegal alien she could be putting herself at risk of deportation. But jurors might well disregard the lay evidence that came in as biased and lacking scientific foundation, since they were deprived of medical evidence.
Although the abuse of discretion standard of review is liberal, the district court's decision to exclude the expert testimony creates a “definite and firm conviction that the district court committed a clear error of judgment.” FN34 Daubert makes the district court a gatekeeper, not a fact finder. When credible, qualified experts disagree, a criminal defendant is entitled to have the jury, not the judge, decide whether the government has proved its case.FN35
Federal Rule of Evidence 702 governs the admission of expert opinion testimony.FN36 Under DaubertFN37 and Kumho Tire,FN38 only relevant and reliable expert opinion testimony is admissible. Expert opinion testimony is relevant if the knowledge underlying it has a “valid ··· connection to the pertinent inquiry.” FN39 And it is reliable if the knowledge underlying it “has a reliable basis in the knowledge and experience of [the relevant] discipline.” FN40
Trial courts must exercise reasonable discretion in evaluating and in determining how to evaluate the relevance and reliability of expert opinion testimony.FN41 Daubert and Kumho Tire suggest factors trial courts may consider when evaluating the relevance and reliability of expert opinion testimony. For example, in evaluating the reliability of scientific expert opinion testimony, trial courts may consider: “(1) whether the scientific theory or technique can be (and has been) tested, (2) whether the theory or technique has been subjected to peer review and publication, (3) whether there is a known or potential error rate, and (4) whether the theory or technique is generally accepted in the relevant scientific community.” FN42 Of course, “there are many different kinds of experts, and many different kinds of expertise,” so these factors “may or may not be pertinent in assessing reliability, depending on the nature of the issue, the expert's particular expertise, and the subject of his testimony.” FN43
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[7] When evaluating specialized or technical expert opinion testimony, “the relevant reliability concerns may focus upon personal knowledge or experience.” FN44 Because medical expert opinion testimony “is based on specialized as distinguished from scientific knowledge, the Daubert factors are not intended to be exhaustive or unduly restrictive.” FN45 Under our decision in Sullivan v. United States Dep't of the Navy, the district court “applied an inappropriately rigid Daubert standard to medical expert testimony” by not accepting what “a good [physician] would in determining what is reliable knowledge in the [medical] profession.” FN46 A trial court should admit medical expert testimony if physicians would accept it as useful and reliable. Utility to the jury of medical expert testimony should be determined by what physicians would accept as useful.
The district court concluded that the proposed medical expert opinion testimony was unreliable because it did not conclusively prove Sandoval-Mendoza's brain tumor caused susceptibility to inducement or a lack of predisposition. But medical knowledge is often uncertain. The human body is complex, etiology is often uncertain, and ethical concerns often prevent double-blind studies calculated to establish statistical proof. This does not preclude the introduction of medical expert opinion testimony when medical knowledge “permits the assertion of a reasonable opinion.” FN47
Predisposition or its absence is the focus of an entrapment defense.FN48 Therefore, medical expert opinion testimony showing that a medical condition renders a person unusually vulnerable to inducement is highly relevant to an entrapment defense. If it is adequately supported by medical expert opinion, it is admissible. Sandoval-Mendoza's experts were well qualified and had sufficient expertise in the neurology of brain tumors and his particular case to be useful to the jury. The district court's exclusion of medical expert opinion testimony prevented Sandoval-Mendoza from showing lack of predisposition, “and thereby deprived him of a fair opportunity to defend himself.” FN49 In this case, the foundation was sufficient. After hearing Drs. Mendius and Shore, the jury could have decided to disbelieve them. But Sandoval-Mendoza was entitled to have the jury decide upon their credibility, rather than the judge. As it was, the jury was left with nothing but unpersuasive lay evidence on a medical matter beyond what laymen could usefully testify about.
The district court excluded the medical expert opinion testimony alternatively in order to avoid “unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.” FN50 But there could be no “confusion of the issues” because predisposition was the issue. Sandoval-Mendoza's only defense was entrapment, and entrapment came down to predisposition. And there was no risk of “misleading the jury.” The experts agreed Sandoval-Mendoza has an unusually large brain tumor. Their only disagreement was whether it caused susceptibility to inducement. The jury was capable of weighing the conflicting medical expert opinion testimony against the rest of the evidence presented and determining whether or not predisposition existed. As for “undue delay,” testimony would likely consume no more time than the Daubert hearing, and probably much less.
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Without the medical expert opinion testimony, the real issue in dispute was hidden from the jury. It could not determine whether the government's informants induced a vulnerable and suggestible man to break the law. The informants did not testify, so the jury could not evaluate the pressure they put on Sandoval-Mendoza. It could not evaluate the merits of Sandoval-Mendoza's suggestibility, because the medical expert opinion testimony concerning the possibility his tumor or limited mental capacity made him susceptible to inducement was excluded. All the jury had was proof that Sandoval-Mendoza sold drugs, wiretap recordings in which he sounded like an experienced drug dealer, and a couple of lay witnesses testifying that he was addled by a brain tumor. Sandoval-Mendoza is entitled to present his case to the jury. For that, he deserves a new trial.
Because this error requires reversal, we need not reach Sandoval-Mendoza's other claims.
REVERSED.
U.S. v. Sandoval-Mendoza L 3783435, *5 -9 (C.A.9 (C.A.9 (Cal.),2006)
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