Plaintiff Dai Trang Thi Nguyen brought this action against Defendant City of San Jose and Individual Supervisor Defendants Joseph Hatfield and Rachel Roberts alleging that a former City Code Inspector William Gerry sexually assaulted and extorted Plaintiff during his code enforcement inspections of her massage business, and Defendants allowed Gerry’s conduct to occur in deliberate indifference to her rights to due process and equal protection.
It is undisputed that former City Code Inspector Gerry repeatedly raped and extorted Plaintiff while inspecting her massage business in 2019.
Defendants filed a motion to exclude the testimony of Officer Antonio Flores and Leonard Powell pursuant to Federal Rule of Evidence 702 while Plaintiff filed a motion to exclude the testimony of Dr. John M. Greene under Federal Rule of Civil Procedure 26.
Law Enforcement Expert Witnesses
Antonio “Tony” Flores has been a police officer with the San Francisco Police Department (“SFPD”) since 1982. During his career, Flores has conducted and supervised “several hundred” massage business inspections, often as many as fifty to sixty per year.
Leonard Powell served as the Code Enforcement Manager, Zoning Administrator, and Deputy Building Official for Dangerous Building Enforcement for the City of Fremont from 2001 to 2020, where he supervised officers enforcing zoning, housing, sanitation, and building codes.
As part of this role, he developed processes and managed investigations in massage business regulation and enforcement, trained and supervised officers, and implemented ethics and accountability systems.
Psychiatry Expert Witness
Dr. John M. Greene is board certified in both General and Forensic Psychiatry. He began practicing in the San Francisco Bay Area in 1997. He became a member of Stanford University’s Adjunct Clinical Faculty in 2005, and currently teaches topics on psychiatry and the law to the residents in the Department of Psychiatry at Stanford.
With extensive training and expertise, Greene is regularly relied upon to provide expert testimony in civil and criminal cases regarding mental illness.
Discussion by the Court
Leonard Powell
a. Helping the Jury Decide the Case
Defendants argued that Powell’s testimony will not help the jury decide whether the City was deliberately indifferent. Powell’s report identified several “best practices” in the code enforcement industry that San Jose was not implementing at the time of Plaintiff’s injury, including: using partner systems for inspections; random supervisory audits; rotation of inspectors across industries; direct supervisory contact with regulated businesses; and formal post-action debriefs. However, during his deposition, Powell testified that he does not believe code inspectors are “likely” to extort or sexually assault people absent those “best practices.”
The Court found that this did not disqualify Powell from testifying as an expert in this case. Although Powell declined to use the word “likely” in his deposition, he also testified there is “a high probability” that lone male enforcement officers would commit sexual assault and corruption, and that lone code enforcement officers going into massage businesses is an outdated practice because “there is a high probability” that something may go wrong.
b. Reliability
Defendants argued that Powell’s opinions are narrowly based on his experience in the City of Fremont and the City of San Rafael, which is insufficient to opine on industry-wide practices.
The Court found Defendants’ arguments unpersuasive. Defendants’ assertion that Powell’s experience is limited only to Fremont and San Rafael is taken out of context and contradicted by his documented experience. As author of the California Code Enforcement Officer Standards Act and CACEO guidelines, Powell drafted California legislation and regulations that established statewide training and ethical standards for code enforcement officers, and he implemented these standards in Fremont. When asked about which other jurisdictions have implemented these standards, he listed San Rafael as one of the “other Bay Area cities” with similar practices.
As for his reliance on external written documents, this is not necessary for Rule 702 purposes.
Powell served as a code inspector supervisor for nearly two decades and authored the California legislation and regulation that established statewide training and ethical standards. In his report and his deposition, he has sufficiently explained how this experience formed his opinions on best practices in this industry, and he relied on that experience to opine on the facts of this case.
c. Common Sense
Finally, Defendants argued that Powell’s opinions on code inspector supervision amount only to “common sense,” not the opinion of an expert.
Defendants also highlighted Powell’s testimony that his reassignment protocols are not specific to code enforcement, but rather are “kind of everywhere in life,” such as in consumer transactions: “If one person has a conflict with somebody else in a commercial setting, the general approach is, ‘Can I talk to somebody else?’”
But, as Plaintiff highlights, Defendants’ excerpts of Powell’s deposition are taken out of context. For example, the phrase “common sense supervisory assessment” was counsel’s, not Powell’s.
And before discussing his general observations of re-assignments in commercial settings, Powell testified that his knowledge of re-assignment practices for code enforcement inspectors was based on his experience in the code enforcement field.
Upon reviewing the whole record, the Court found that Powell sufficiently used his expertise in the code enforcement industry, rather than common sense available to any lay person, to provide his opinions.
Antonio Flores
a. Expertise
Defendants first argued that Flores lacked the code enforcement expertise necessary to offer opinions about the industry because he is a police officer, not a code enforcement inspector.
The Court found that, despite his role as a police officer, Flores possessed the expertise required under Rule 702 to testify on code enforcement practices in massage businesses. Though Flores has never been a code inspector, Flores has worked extensively with code enforcement inspectors in his “several hundred” massage business inspections. Flores also testified that he has seen code inspectors operate with enforcement powers akin to those of police officers, particularly in the eyes of certain vulnerable communities including illicit massage business employees, such that the distinction between police officer and code enforcement investigator may be immaterial in this context.
b. Reliability
Next, Defendants argued that Flores lacked reliable support for his opinion that sexual assault or extortion is the likely outcome of a solo male code inspector working in massage businesses.
Defendants contended that Flores testified he was not aware of any other instance in his experience in which a code enforcement inspector assaulted or extorted a massage business worker; he is not aware of any standards applicable to supervising code inspectors; he is not aware of any jurisdiction that actually supervises code enforcement inspectors the way he opines they should be supervised; and he could not point to any written standards that suggest re-assigning an employee about whom a complaint has been made.
Analysis
First, whether similar conduct has occurred in the past is not necessarily relevant to the theory of Plaintiff’s case—that the risks of exploitation were so obvious and well-known in the industry that the City did not need a pattern of similar instances to be on constructive notice.
Second, Flores’s lack of experience in code enforcement supervision could foreseeably render some opinions on code enforcement inadmissible, but it does not render his entire testimony unreliable. Flores still sufficiently explained how he formed his opinions on code enforcement best practices based on his observations, trainings, and teachings conducted over forty-three years in the SFPD overseeing code enforcement inspections in massage businesses—including observations of employees vulnerable to exploitation, power dynamics, intimate spaces, and code enforcement investigators’ use of police powers.
Third, as the Court noted above, written standards on re-assigning code inspectors after receiving complaints is unnecessary to forming a reliable opinion. The Court found that Flores may rely “solely or primarily on experience” because he has sufficiently explained how his experiences have led to his conclusions on code enforcement best practices in massage businesses, why that experience is a sufficient basis for his opinions, and how his experience is reliably applied to the facts of this case.
c. Common Sense
Finally, Defendants also argued that Flores’ opinions are no more than “common sense.” But upon review of the cited potions of Flores’ testimony, it appeared that Flores’ use of “common sense” referred to “common sense” among industry professionals.
Upon reviewing Flores’s report and testimony in its entirety, the Court is satisfied that his opinions are based on his relevant experience, including experience conducting massage business inspections, rather than on the common sense available to any lay person.
Accordingly, the Court also found that Flores is qualified as an expert by his knowledge, skill, experience, training, and education in the field of massage business inspections.
John Greene
Unlike Powell and Flores, Plaintiff did not challenge the admissibility of Greene’s opinions under Rule 702.
Defendants first disclosed Greene during fact discovery on August 19, 2025, as the person who would conduct a psychiatric independent medical examination (“IME”) on Plaintiff. Plaintiff argued that Greene’s opinion must be excluded because Greene is not a “rebuttal” expert, but rather an initial expert, and he should have been disclosed as such prior to the deadline for initial expert disclosure on September 22, 2025.
The Court agreed with Plaintiff that the timing of the IME and Greene’s report was unusual. However, Plaintiff has not provided any authority prohibiting the use of prior findings to rebut the opinion of an initial expert during trial. So long as Greene’s testimony only uses his IME findings to narrowly contradict or rebut the initial expert’s opinions on the same subject matter, the Court sees no reason for exclusion.
Held
- The Court denied the Defendants’ motion to exclude the testimony of Antonio Flores and Leonard Powell.
- The Court also denied the Plaintiff’s motion to exclude the testimony of John Greene.
Key Takeaway
So long as the witness “explains how that experience leads to the conclusion reached, why that experience is a sufficient basis for the opinion, and how that experience is reliably applied to the facts,” than the witness may rely “solely or primarily on experience.”
Case Details:
| Case Caption: | Dai Trang Thi Nguyen V. City of San Jose |
| Docket Number: | 5:21cv92 |
| Court Name: | United States District Court, California Northern |
| Order Date: | January 22, 2026 |
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