Plaintiff January Villareal claimed that during her December 16, 2021 arrest on suspicion of driving under the influence, former San Jose Police Officer Matthew Dominguez inappropriately touched her as she sat handcuffed in the back of his patrol vehicle.
Dominguez filed a motion to exclude one of the opinions offered by Villareal’s retained expert, Dr. Randall C. Epperson, a clinical neuropsychologist, regarding the cognitive decline Villareal claims she suffered as a result of the incident at issue while Villareal filed a motion to preclude all testimony and opinions of Defendants’ retained expert and forensic psychiatrist, Dr. Marc A. Cohen.
Neuropsychology Expert Witness
Randall C. Epperson, Ph.D. has received training in post-traumatic stress disorder and cognitive decline diagnosis and emotional harm related to sexual assault victims as a clinical and forensic neuropsychologist over the last 40 years.
Epperson has testified as a neuropsychology expert in over a hundred state and federal cases regarding emotional harm, including post traumatic stress disorder and cognitive decline.
Psychiatry Expert Witness
Marc Alan Cohen obtained a Master’s of Science degree in Physiological Science from the University of California, Los Angeles. He received an M.D. degree from the Keck School of Medicine at the University of Southern California in 2003. Cohen then completed a psychiatric residency training program at the University of California, Los Angeles-San Fernando Valley Psychiatry Residency Training Program, and thereafter completed a fellowship in forensic psychiatry at the University of California, Los Angeles. Cohen is board certified in psychiatry and forensic psychiatry by the American Board of Psychiatry and Neurology.
Discussion by the Court
Randall Epperson
Dominguez argued that Epperson did not have sufficient data to reliably opine that Villareal has “Neurocognitive Disorder, unspecified (reduction in cognitive efficiency due to emotional stress and depression)” and that she experienced cognitive decline as a result of the alleged incident with Dominguez.
In his report, Epperson stated that Villareal’s “intellectual level has dropped from 112 (high average) to 90 (bottom of average range, 25%).” It appeared to be undisputed that Epperson did not have data regarding Villareal’s intellectual level prior the incident at issue.
Villareal did not dispute that Epperson had no data or other information about Villareal’s intellectual level or her cognitive functioning before the incident. She argued, however, that Epperson’s opinion is admissible because he relied on the Wechsler Test of Premorbid Functioning and the Wonderlic Test in his analysis.
Villareal acknowledged that Epperson’s assessments relied on indicators consisting of “the mean IQ of individuals with her education level (120) and work experience (113, 113, and 114)” as well as two assessment indicators—non-phonetically spelled English words (108) and English vocabulary (104)—that are “relatively resistant to deterioration.”
From these indicators, Epperson concluded that Villareal’s pre-incident IQ was 112 and had dropped to 90 as a result of the incident.
Epperson’s report disclosed the assessments he conducted and their results, but it included no explanation demonstrating that these one-time assessments of intellectual level may be used reliably to measure cognitive decline or to attribute the cause of any such decline to the incident in question. However, the Court will not preclude Epperson from testifying about his assessment that Villareal has “Neurocognitive Disorder, unspecified,” to the extent that testimony reflects his assessment of Villareal’s current cognitive functioning.
Marc Cohen
Villareal did not challenge Cohen’s qualifications. However, she argued that Cohen’s proposed testimony is unreliable because he did not personally examine her or conduct any formal testing. Additionally, Villareal argued that Cohen’s proposed testimony is unhelpful and improperly invaded the fact-finding province of the jury.
Under the circumstances presented, the lack of a psychiatric examination of Villareal diminished the utility of Cohen’s testimony in helping the trier of fact to understand the evidence or to determine a fact in issue regarding, for example, the existence, causes, or sources of Villareal’s claimed emotional distress; the more “plausible” bases for Villareal’s PTSD diagnosis; the validity of her attribution of her symptoms to Dominguez’s alleged conduct; and the reliability of her memories of the events in question.
Cohen’s report included commentary, opinions, and conclusions purporting to tell the jury the import and interpretation of, as well as inferences and conclusions to be drawn from, a timeline of events, Villareal’s medical records, other events or issues in Villareal’s life, Villareal’s statements and conduct, and other evidence of events as they unfolded. Such opinions intrude on the jury’s role in making credibility and other determinations of facts at issue.
While Cohen is permitted to opine that the events as alleged by Villareal, if true, could not result in PTSD, the Court held that Cohen will not be permitted to testify or offer opinions regarding the existence, causes, or sources of Villareal’s claimed emotional distress.
Held
- The Court granted in part and denied in part Dominguez’s motion to exclude a portion of Dr. Randall Epperson’s testimony.
- The Court granted in part and denied in part Villareal’s motion to exclude the testimony of Dr. Marc Cohen.
Key Takeaway
Cohen offered opinions and conclusions regarding evidence that jurors are capable of reviewing for themselves based on their own experience, without the aid of scientific, technical, or other specialized knowledge.
There was no abuse of discretion in the determination that expert testimony would not aid the jury in evaluating evidence that was fully presented and within the understanding of the average juror.
Case Details:
| Case Caption: | Villareal V. City Of San Jose |
| Docket Number: | 5:22cv9152 |
| Court Name: | United States District Court, California Northern |
| Order Date: | April 10, 2026 |
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