Peo v. Nguyen

22CA2152 Peo v Nguyen 10-22-2026 COLORADO COURT OF APPEALS Court of Appeals No. 22CA2152 City and County of Denver District Court No. 20CR2658 Honorable Martin F. Egelhoff, Judge The People of the State of Colorado, Plaintiff-Appellee, v. Jenny M. Nguyen, Defendant-Appellant. JUDGMENT REVERSED AND CASE REMANDED WITH DIRECTIONS Division VII Opinion by JUDGE PAWAR Brown and Moultrie, JJ., concur NOT PUBLISHED PURSUANT TO C.A.R. 35(e) Announced October 22, 2026 Philip J. Weiser, Attorney General, Sonia Raichur Russo, Senior Assistant Attorney General, Denver, Colorado, for Plaintiff-Appellee Megan A. Ring, Colorado State Public Defender, Emily Hessler, Deputy State Public Defender, Denver, Colorado, for Defendant-Appellant ¶1 Defendant, Jenny M. Nguyen, appeals her convictions of manslaughter and tampering with physical evidence after she shot and killed her boyfriend. We reverse and remand because we conclude that the trial court violated Nguyen’s constitutional right to present a complete defense by excluding part of her expert’s testimony. I. Background ¶2 Nguyen shot and killed her boyfriend, with whom she had a volatile and violent relationship. The incident occurred in front of Nguyen’s house, and part of it was captured on Nguyen’s home surveillance camera. Immediately after the shooting, Nguyen deleted some footage from the surveillance system and attempted to hide her gun. ¶3 The prosecution charged Nguyen with first degree murder and two counts of tampering with physical evidence for deleting the security camera footage and hiding the gun. Before trial, Nguyen filed notice of her intent to introduce evidence of her mental condition under section 16-8-107(3)(b), C.R.S. 2026, which triggered a court-ordered examination by a psychiatrist or forensic psychologist under section 16-8-106(1)(a), C.R.S. 2026. Nguyen 1  then underwent two examinations: one by her expert, a marriage and family therapist; and another pursuant to a court order, conducted by a forensic psychiatrist. The therapist diagnosed Nguyen with PTSD. The forensic psychiatrist concluded that Nguyen did not have PTSD. ¶4 At trial, the defense sought to introduce the therapist’s PTSD diagnosis. The therapist was qualified as an expert and testified generally about trauma, the dynamics of domestic violence and abusive relationships, and Nguyen’s history of trauma. However, the court prohibited the therapist from testifying about Nguyen’s PTSD diagnosis because, according to the court, the diagnosis was beyond the scope of the therapist’s expertise. ¶5 The forensic psychiatrist who conducted the court-ordered examination also testified as an expert. He testified that Nguyen did not suffer from PTSD. ¶6 The jury found Nguyen not guilty of first degree murder but guilty of reckless manslaughter, a lesser included offense. It also found her guilty of the two tampering offenses. She was convicted and sentenced accordingly. 2 ¶7 On appeal, Nguyen argues that the court erred by (1) excluding the therapist’s PTSD diagnosis; (2) failing to suppress the video evidence from her surveillance system; and (3) allowing the prosecutor to engage in misconduct during trial. We agree with her first argument and conclude that this error requires reversal. We therefore do not address her additional arguments. II. The Therapist’s Excluded Expert Testimony ¶8 Nguyen argues that excluding the therapist’s PTSD diagnosis violated not only the Colorado Rules of Evidence but also her constitutional right to present a complete defense. We review the exclusion of expert testimony under the evidentiary rules for an abuse of discretion. Kutzly v. People, 2019 CO 55, ¶ 8. If the trial court abused its discretion, we review de novo whether that abuse of discretion violated a constitutional right. See People v. Carter, 2015 COA 24M-2, ¶ 28. ¶9 Nonconstitutional errors require reversal unless the Attorney General shows that the error was harmless. James v. People, 2018 CO 72, ¶ 18. However, if the error was constitutional, the Attorney General must show that the error was harmless beyond a 3  reasonable doubt to avoid reversal. People v. Butler, 224 P.3d 380, 386 (Colo. App. 2009). ¶ 10 We conclude that the exclusion of the therapist’s PTSD diagnosis violated the evidentiary rules and Nguyen’s constitutional right to present a defense, and that the Attorney General has failed to show that this error was harmless beyond a reasonable doubt. A. Excluding the PTSD Diagnosis Was Evidentiary and Constitutional Error ¶ 11 We start with evidentiary error. CRE 702 provides that a witness may provide expert testimony if they are qualified to do so by knowledge, skill, experience, training, or education. This qualification standard is liberal. People v. Douglas, 2015 COA 155, ¶ 71 (citing Golob v. People, 180 P.3d 1006, 1012 (Colo. 2008)). To be qualified to give expert testimony on a particular issue, “[t]here is no requirement that a witness hold a specific degree, training certificate, accreditation, or membership in a professional organization.” Huntoon v. TCI Cablevision of Colo., Inc., 969 P.2d 681, 690 (Colo. 1998). Instead, an expert witness can be qualified based on any one or more of the five factors identified in CRE 702. Huntoon, 969 P.2d at 690. 4 ¶ 12 Applying this liberal standard, we conclude the therapist’s testimony established that her knowledge, experience, education, and training qualified her to diagnose PTSD. The therapist was licensed in marriage and family therapy and had a master’s degree in psychology. She described her decades-long experience providing therapy to victims of domestic violence and explained that she had conducted workshops for other therapy professionals, attorneys, and judges to help them understand the dynamics of domestic violence, including the impacts of trauma. She testified that ninety-five percent of the clients in her practice have experienced trauma. ¶ 13 The therapist also explained that her master’s degree included “courses on the ability to diagnose — we study all of the different mental health disorders. And then I also receive additional training around learning how to make diagnoses and deal with diagnoses.” Defense counsel asked, “In your role[,] are you qualified to make diagnoses?” She responded, “I am.” She then described her process of making diagnoses, which included conducting a clinical interview, reviewing a client’s psychosocial history, and using checklists or instruments from “the diagnostic and statistical 5  manual which is kind of like the dictionary of mental health disorders.” ¶ 14 The court qualified the therapist as an expert in the dynamics of domestic violence and “the effects on [Nguyen].” But when defense counsel later asked the therapist about the specific inventory she completed on Nguyen that led to the PTSD diagnosis, the prosecution objected, arguing that she was not qualified to give that testimony. The trial court agreed, ruling that “if [defense counsel was] going to try to establish some sort of diagnosis, that’s beyond [the expert’s] expertise.” ¶ 15 We conclude that this was an abuse of discretion. The therapist testified that she had spent decades working with victims of trauma, taught other mental health professionals about the effects of trauma, and received postgraduate training on diagnosing mental health disorders, of which PTSD is one. She also described the general process she used to diagnose mental health disorders. This unchallenged testimony established that she had the knowledge, experience, education, and training to diagnose Nguyen with a mental health disorder. And the court did not explain why it concluded that she was not so qualified. 6 ¶ 16 We are not persuaded otherwise by the Attorney General’s reliance on the insanity statutes, sections 16-8-101 to -122, C.R.S. 2026. In the trial court, the prosecution primarily relied on section 16-8-106(1)(a), which sets out the requirements for a court-ordered examination, including that it must be conducted by a psychiatrist or forensic psychologist. But the therapist here did not conduct a section 106 examination. Instead, she conducted an examination at the request of the defense. Section 106 has no bearing on whether a defense-chosen examiner is qualified to make a diagnosis based on an examination. It expressly “does not abridge the right of the defendant to procure an examination as provided in section 16- 8-108[, C.R.S. 2026].” § 16-8-106(1)(a). And section 108(1)(a) explicitly contemplates that a defense-chosen examiner can be an expert who is neither a psychiatrist nor a psychologist. § 16-8- 108(1)(a) (“If the defendant wishes to be examined by a psychiatrist, psychologist, or other expert of the defendant’s own choice . . . .”). ¶ 17 On appeal, the Attorney General asserts that once Nguyen gave notice of her intent to introduce expert evidence regarding her mental condition under section 16-8-107(3)(b), she was required to comply with section 16-8-108(1)(a) in obtaining her own expert 7  evaluation. The Attorney General further argues that Nguyen “did not comply with section 16-8-108’s requirements to make a timely motion for . . . an examination and that the examination be video and audio recorded.” But like section 106, section 108(1)(a)’s requirements apply to court-ordered examinations, not those arranged voluntarily by the defense like the therapist’s evaluation here. See § 16-8-108(1)(a) (“An interview conducted pursuant to a court order under this section must be video and audio recorded and preserved.” (emphasis added)). In any event, we do not see, and the Attorney General has not explained, how Nguyen’s alleged failure to comply with section 108(1)(a)’s procedural requirements rendered the therapist unqualified to diagnose Nyugen with PTSD. ¶ 18 The Attorney General further argues that despite the therapist’s testimony about her qualifications, she did not testify about “PTSD-specific qualifications,” such as how much training and experience she had diagnosing PTSD, how many patients she had diagnosed with it, and whether she regularly diagnoses it. But the Attorney General cites no authority holding that such condition- specific expertise is required under CRE 702, and we are aware of none. In fact, the only authority the Attorney General cites in 8  support of this assertion suggests the opposite. In People in Interest of Martinez, 841 P.2d 383, 384 (Colo. App. 1992), a division of this court held that a psychiatric resident was qualified to provide expert testimony about the respondent’s certification for short-term mental health treatment because he was a medical resident who “was responsible for performing independent diagnoses and providing treatment for mentally ill patients.” The division did not require any information about what specific mental illnesses the resident had diagnosed or with what frequency. Id. ¶ 19 In sum, based on the therapist’s testimony about her knowledge, experience, training, and education, we conclude that the trial court abused its discretion by precluding her from testifying about having diagnosed Nguyen with PTSD. Nothing in the therapist’s testimony or the trial court’s ruling indicates that the PTSD diagnosis was outside the scope of the therapist’s expertise. We must therefore conclude that excluding the diagnosis was manifestly arbitrary. See People v. Claycomb, 2025 COA 36, ¶ 14 (defining a ruling as an abuse of discretion when it is “manifestly arbitrary, unreasonable, or unfair”). 9 ¶ 20 We also conclude that this abuse of discretion violated Nguyen’s constitutional right to present a defense. Criminal defendants have a constitutional right to “a meaningful opportunity to present a complete defense.” Rios-Vargas v. People, 2023 CO 35, ¶ 20 (quoting Holmes v. South Carolina, 547 U.S. 319, 324 (2006)). This right ensures that a defendant can present their version of the facts so that the jury may contrast it with the prosecution’s and decide where the truth lies. Id. at ¶ 21 (citing Washington v. Texas, 388 U.S. 14, 19 (1967)). This right is violated if the defendant is denied “virtually [her] only means of effectively testing significant prosecution evidence.” Krutsinger v. People, 219 P.3d 1054, 1062 (Colo. 2009). ¶ 21 The Attorney General does not dispute that if the trial court erred by excluding the therapist’s PTSD diagnosis, that error was constitutional. We can see why. It was uncontested at trial that Nguyen shot and killed her boyfriend, deleted security camera footage, and attempted to hide the gun. The main issues at trial were Nguyen’s culpable mental states for the charged offenses and whether she acted in self-defense. 10 ¶ 22 The expert who conducted the court-ordered evaluation testified that Nguyen did not suffer from PTSD, thus making it more likely that she acted with the requisite culpable mental states for the charged offenses. The therapist’s excluded PTSD diagnosis was the only way Nguyen could have directly countered the prosecution’s expert, by allowing her to argue that her past trauma was significant enough that it decreased the likelihood that she acted with the requisite mens rea for the charged offenses. The trial court’s ruling deprived Nguyen of her only means of challenging the prosecution’s expert testimony, which bore directly on the main issue in the case. Under these circumstances, we conclude that the court’s error violated Nguyen’s constitutional right to present a complete defense. B. Reversal Is Required ¶ 23 Because the error was constitutional, we next address whether the Attorney General has carried their burden to prove that the error was harmless beyond a reasonable doubt. See Hagos v. People, 2012 CO 63, ¶ 11. An error is harmless beyond a reasonable doubt if there is no reasonable possibility that it contributed to the conviction. Id. 11 ¶ 24 The Attorney General argues that there was no such reasonable possibility here because the therapist testified extensively about domestic violence dynamics, how those dynamics might have affected Nguyen in her relationship with her boyfriend, and Nguyen’s extensive history of experiencing domestic violence, abuse, and trauma. In short, the Attorney General contends that despite the excluded diagnosis, the therapist nevertheless described how Nguyen’s past trauma might have impacted her on the night of the shooting. ¶ 25 We agree that the therapist testified extensively on these topics. But the prosecution’s expert testified that Nguyen did not suffer from PTSD, thereby suggesting that the effect of her past trauma did not rise to the level of a mental health disorder. This testimony diminished the purported effect of Nguyen’s past trauma on her mental state on the night of the shooting. ¶ 26 The therapist’s PTSD diagnosis would have suggested that the impact of Nguyen’s past trauma did rise to the level of a mental health disorder and had a more significant effect on her mental state at the time of the shooting. Both reckless manslaughter and tampering required that Nguyen acted consciously. Reckless 12  manslaughter required that Nguyen consciously disregarded a substantial and unjustifiable risk. See § 18-3-104(1)(a), C.R.S. 2026 (manslaughter requires recklessness); § 18-1-501(8), C.R.S. 2026 (defining “reckless”). And tampering required that Nguyen acted with a conscious objective. See § 18-8-610(1)(a), C.R.S. 2026 (tampering requires that a defendant act with intent to impair the evidence’s availability); § 18-1-501(5) (defining “with intent”). The greater the impact of Nguyen’s past trauma on her mental state, the less likely it was that she fired the gun with conscious disregard of a substantial and unjustifiable risk (recklessly) or destroyed evidence with the conscious objective (with intent) to impair its availability. ¶ 27 We therefore conclude that it was at least reasonably possible that the excluded testimony contributed to Nguyen’s convictions. Because the Attorney General has failed to prove that the error was harmless beyond a reasonable doubt, we must reverse all Nguyen’s convictions.1 1 Nguyen argues on appeal that the trial court’s error requires reversal of all her convictions. In arguing harmlessness beyond a reasonable doubt, the Attorney General does not distinguish between the error’s impact on the manslaughter conviction and the tampering convictions. We therefore do not address any distinction 13 ¶ 28 Based on this conclusion, we neither address nor express any opinion about Nguyen’s additional allegations of error. See People v. Price, 2023 COA 96, ¶ 30 (reversing conviction and declining to address an additional issue because any opinion on that issue would be advisory). Consequently, the trial court has discretion whether to reconsider its rulings that were challenged but not addressed in this appeal. III. Disposition ¶ 29 The judgment is reversed, and the case is remanded to the trial court for further proceedings consistent with this opinion. JUDGE BROWN and JUDGE MOULTRIE concur. that might or might not exist. Because we conclude the Attorney General has not proved constitutional harmlessness with regard to any of Nguyen’s convictions, we reverse them all. See People v. Hernandez, 2019 COA 111, ¶ 43 (the Attorney General bears the burden of proving the “high bar” of constitutional harmlessness (quoting People v. Godinez, 2018 COA 170M, ¶ 84)). 14