Elizabeth Mirabelli, et al. v. Mark Olson, et al.

• Court: District Court, S.D. California
• Decided: October 23, 2025
• Docket: 3:23-cv-00768
• Status: Unknown

Opinion

1 2 3 4 5 6 7 8 UNITED STATES DISTRICT COURT 9 SOUTHERN DISTRICT OF CALIFORNIA 10 11 ELIZABETH MIRABELLI, et al., ) Case No.: 23-CV-00768-BEN-VET ) 12 Plaintiff, ) ORDER DENYING PLAINTIFFS’ 13 v. ) MOTION TO EXCLUDE THE ) TESTIMONY OF DEFENDANTS’ 14 MARK OLSON, et al., ) EXPERTS DARLENE TANDO AND 15 Defendant. ) CHRISTINE BRADY ) 16 ) [Dkt No. 243] 17 ) ) 18 ) 19 20 Plaintiffs’ motion to exclude the testimony of Defendants’ experts, Darlene Tando, 21 LCSW, and Christine Brady, Ph.D., is DENIED under Federal Rule of Evidence 403 and 22 702. 23 I. BACKGROUND 24 Plaintiffs Elizabeth Mirabelli, Lori Ann West, and others bring this action on behalf of 25 themselves and a putative class challenging school district policies regarding the social 26 transition of students who identify as transgender. The central dispute concerns whether 27 California’s public school teachers and staff may notify parents when a student uses a 28 1 different name or different pronouns or gender expressions that diverge from the name 2 and sex assigned to the child at birth. 3 Defendants designate two expert witnesses: (1) Christine Brady, Ph.D., a clinical 4 psychologist and Clinical Associate Professor at Stanford University School of 5 Medicine’s Pediatric and Adolescent Gender Clinic; and (2) Darlene Tando, LCSW, a 6 licensed clinical social worker who has counseled gender nonconforming youth since 7 2006. 8 Plaintiffs contend these experts’ opinions: (1) rely on unreliable principles, including 9 quasi-spiritual beliefs; (2) lack sufficient factual basis; (3) contradict constitutional 10 principles; (4) contain internal inconsistencies; and (5) are cumulative. 11 12 II. LEGAL STANDARD

13 Federal Rule of Evidence 702 establishes several requirements for admissibility of 14 expert opinion evidence: (1) the witness must be sufficiently qualified as an expert by 15 knowledge, skill, experience, training, or education; (2) the “scientific, technical, or other 16 specialized knowledge must assist the trier of fact” either “to understand the evidence” or 17 “to determine a fact in issue”; (3) the testimony must be “based on sufficient facts or 18 data”; (4) the testimony must be “the product of reliable principles and methods”; and (5) 19 the expert must reliably apply the principles and methods to the facts of the case. Fed. R. 20 Evid. 702. “Consistent with the 2023 amendment . . . Rule 702 requires a proponent of 21 expert testimony to demonstrate each of the requirements of Rule 702 by a 22 preponderance of the evidence.” Engilis v. Monsanto Co., __ F.4th __, 2025 U.S. App. 23 LEXIS 20377, 2025 WL 2315898, *16 (9th Cir. Aug. 12, 2025). 24 The trial court must ensure expert testimony “both rests on a reliable foundation and is 25 relevant to the task at hand.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 597 26 (1993). “Shaky but admissible evidence is to be attacked by cross-examination, contrary 27 evidence, and careful instruction on the burden of proof, not exclusion.” Primiano v. 28 Cook, 598 F.3d 558, 564 (9th Cir. 2010) (citation omitted). The inquiry focuses on 1 methodology, not the correctness of conclusions. Engilis, 2025 WL 2315898, at *16. 2 While doubtful testimony may be admitted, “‘shaky’ expert testimony, like any expert 3 testimony, must still be ‘admissible,’ and this requires a determination by the trial court 4 that it satisfies the threshold requirements established by Rule 702.” Id. (citations 5 omitted). 6 III. DISCUSSION 7 The Court makes no credibility determinations and assigns no particular weight to the 8 experts’ opinions at this stage. The testimony is admissible so long as it does not mislead 9 or confuse the Court.1 Plaintiffs’ primary criticisms go to weight, not admissibility. 10 A. Challenges Go to Weight, Not Admissibility 11 Plaintiffs argue that Tando’s statements that gender identity is “part of a person’s 12 soul” and her references to “male and female brains” reflect quasi-spiritual rather than 13 scientific foundations for her opinions. See e.g., Ex. A, Tando Dep. 74:23-24, 77:9-14, 14 79:4-11, 86:20-25. While such statements can affect the credibility of the witness, they 15 do not render the entirety of the testimony inadmissible. Plaintiffs also note the absence 16 of studies examining social transition without parental involvement, while the cited 17 literature presumes parental participation. See Anderson Rep. ¶129. The Court 18 acknowledges the absence of supporting research for healthy gender transition without 19 parental involvement. This absence, however, does not render inadmissible Tando’s 20 testimony based on broader clinical experience with transgender youth. The limitation 21 concerns weight rather than admissibility. Plaintiffs contend the defense experts 22 misunderstand “non-pathological” to mean “natural” or “innate,” and extrapolate that 23 24

25 1 “‘Expert evidence can be both powerful and quite misleading because of the difficulty 26 in evaluating it. Because of this risk, the judge in weighing possible prejudice against 27 probative force under Rule 403 of the present rules exercises more control over experts than over lay witnesses.’” Daubert v. Merrell Dow Pharms., Inc. 509 U.S. 595 (1993) 28 1 status to require gender affirmation in all cases. Szajnberg Rep. ¶¶15-22; Ex. A, Tando 2 Dep. 324:5-18; Ex. B, Brady Dep. 222:15-223:17. Plaintiffs highlight the fact that both 3 experts -- in their own practices -- refuse to treat minors without parental consent. Ex. A, 4 Tando Dep. 56:18-57:20; Ex. B, Brady Dep. 216:18-218:7. The reality of their own 5 practices does tend to contradict their view that schools may facilitate gender transition 6 safely without parental involvement.2 Even so, the experts’ ongoing clinical experiences 7 counseling transgender youth provides a sufficient foundation here for admissibility. 8 Plaintiffs’ arguments may go to credibility; they do not warrant exclusion. 9 Plaintiffs also argue that the experts’ opinions run contrary to constitutional principles 10 that sometimes require individualized determinations of parental fitness. See e.g., Stanley 11 v. Illinois, 405 U.S. 645, 656-57 (1972).3 At the same time, there is also a general 12 constitutional presumption that fit parents act in their children’s best interests. Troxel v. 13 Granville, 530 U.S. 57, 68 (2000). As the Supreme Court has observed, “historically [the 14 law] has recognized that natural bonds of affection lead parents to act in the best interests 15 of their children[;] . . . so long as a parent adequately cares for his or her children (i.e., is 16 fit), there will normally be no reason for the State to inject itself into the private realm of 17 the family to further question the ability of that parent to make the best decisions 18 concerning the rearing of that parent's children.” Id. at 68-69 (citations omitted). While 19 these principles, including the presumption that fit parents act in their children’s best 20 21 22 2 While Plaintiffs highlight this contradiction, Engilis requires only that where experts 23 “rules out a potential cause,” they must “provide scientifically sound reasons.” 2025 U.S. App. LEXIS 20377, 2025 WL 2315898, at *10. The experts’ professional practice may 24 differ from their opinions about school policies without rendering their testimony 25 inadmissible. 3 “Procedure by presumption is always cheaper and easier than individualized 26 determination. But when, as here, the procedure forecloses the determinative issues of 27 competence and care, when it explicitly disdains present realities in deference to past formalities, it needlessly risks running roughshod over the important interests of both 28 1 interests, maintain their vitality, expert opinion admissibility under Rule 702 does not 2 turn on constitutional alignment; such issues go to the merits. 3 B. Expert Disagreement Is Not a Basis for Exclusion 4 In essence, Plaintiffs contend that their experts are “right” and Defendants’ experts are 5 “wrong” requiring exclusion. “Correctness,” however, is not the admissibility standard. 6 “The inquiry envisioned by Rule 702 is, we emphasize, a flexible one. Its overarching 7 subject is the scientific validity—and thus the evidentiary relevance and reliability—of 8 the principles that underlie a proposed submission. The focus, of course, must be solely 9 on principles and methodology, not on the conclusions that they generate.” Daubert v. 10 Merrell Dow Pharms., Inc., 509 U.S. 579, 594-95 (1993). Clinical experience with 11 patients, peer discussions, and thorough examinations, are “tools of the [medical] trade” 12 that can support opinions even where peer-reviewed studies are limited. Engilis, 2025 13 U.S. App. LEXIS 20377, 2025 WL 2315898, at *9 (“To be sure, an expert’s specialized 14 knowledge and experience is of critical significance when the district court determines 15 whether a witness is ‘qualified as an expert.’”); Heller v. Shaw Indus., Inc., 167 F.3d 146, 16 155 (3d Cir. 1999).4 17 18 Criticizing the defense expert opinions, the Plaintiffs point out for example that the 19 Cass Review found no clear evidence that social transition in childhood has positive or 20 negative mental health outcomes, and only “relatively weak” evidence for positive effects 21 of social transition in adolescence. ECF 247-10, Ex. 1, ¶131. Yet, Engilis found that 22 experts need not “conclusively identify the sole cause of a medical condition.” 2025 U.S. 23 App. LEXIS 20377, 2025 WL 2315898, at *10. Here, Defendants’ experts need only 24

25 4 “The Supreme Court has held that it was not an abuse of a district court’s discretion to 26 exclude expert testimony when there was ‘too great an analytical gap between the data 27 [of scientific studies] and the opinion proffered’. . .but we do not read the Supreme Court as requiring a medical expert to always rely on published studies indicating the exposure 28 1 demonstrate their opinions meet Rule 702’s requirements by a preponderance of the 2 evidence, not that they have definitively proven causation or eliminated all alternative 3 explanations. As a result, the Court finds that such disagreement about whether there are 4 mental health benefits from transitioning goes to weight, not admissibility. Primiano, 5 598 F.3d at 565-66 (“When an expert meets the threshold established by Rule 702 as 6 explained in Daubert, the expert may testify and the jury decides how much weight to 7 give that testimony.”). 8 Additionally, because this matter proceeds to a bench trial, standards for excluding 9 expert testimony apply with additional flexibility. “Daubert is meant to protect juries 10 from being swayed by dubious scientific testimony.” United States v. Flores, 901 F.3d 11 1150, 1165 (9th Cir. 2018). “When the district court sits as the finder of fact, there is less 12 need for the gatekeeper to keep the gate when the gatekeeper is keeping the gate only for 13 himself.” Id. (citation omitted); FTC v. BurnLounge, Inc., 753 F.3d 878, 888 (9th Cir. 14 2014).5 15 Alternatively, Plaintiffs request limiting Defendants to one expert witness (either Dr. 16 Brady or LCSW Tando). ECF 243 at 21:23-25:15. Rule 403 exclusion is to be applied 17 cautiously and sparingly. Sidibe v. Sutter Health, 103 F.4th 675, 691 (9th Cir. 2024). Dr. 18 Brady and LCSW Tando represent distinct disciplines. For example, Tando’s counseling 19 emphasizes social systems, skill development, and client advocacy. Bunshoft Decl., Ex. 20 2 at 26:1-17, 29:24-30:5. Defendants argue that the two experts offer different 21 disciplinary approaches, and each obtains different perspectives from different client 22 23 24 5 “When we consider the admissibility of expert testimony, we are mindful that there is 25 less danger that a trial court will be unduly impressed by the expert’s testimony or opinion in a bench trial.”; Flores, 901 F.3d at 1165 (“In bench trials, the district court is 26 able to ‘make its reliability determination during, rather than in advance of, trial. Thus, 27 where the factfinder and the gatekeeper are the same, the court does not err in admitting the evidence subject to the ability later to exclude it or disregard it if it turns out not to 28 1 ||bases. The Court finds these differences sufficient. Sidibe, 103 F.4th at 691 (“Rule 403 2 || tilts, as do the rules as a whole, toward the admission of evidence in close cases.”’) 3 (citation omitted). Accordingly, the Court DENIES Plaintiffs’ request to exclude Tando 4 || and Dr. Brady for duplicative reasons. IV. CONCLUSION Of course, for admission as evidence, Rule 702 still requires the drawing of, and g respect for, boundary lines around expert opinion. Engilis, 2025 U.S. App. LEXIS 9 20377, 2025 WL 2315898, at *14 (“The [2023] amendment [to FRE 702] aimed ‘to 10 emphasize that each expert opinion must stay within the bounds of what can be ll concluded from a reliable application of the expert's basis and methodology.’”). Those 12 boundary lines have not yet been drawn at trial. For the present, for the reasons set forth 13 above, Plaintiffs’ Motion to Exclude the Testimony of Defendants’ Expert Darlene Tando 14 and Christine Brady is DENIED. !5 || IS SO ORDERED. lyin, 16! DATED: October 23, 2025 17 HON. ROGER T. BENITEZ 18 United States District Judge 19 20 21 22 23 24 25 26 27 28 _7-