Lopez v. People (2026 CO 23): Repeated Coaching Allegations “Open the Door” to Limited Expert Testimony of No Indicia of Coaching

Court: Colorado Supreme Court (en banc)
Date: April 13, 2026
Author: Justice Samour (Hood, Gabriel, Berkenkოტter joining)
Dissent: Chief Justice Márquez (Boatright, Blanco joining)

1. Introduction

Lopez, Gustavo v. People is a child sexual-assault prosecution in which the central trial dispute was credibility—specifically, whether two child victims’ later disclosures to a forensic interviewer were genuine or were the product of coaching and improper influence by their maternal grandmother, who allegedly sought to retain custody.

At trial, the People called Kim Grimm, the forensic interviewer, qualified (without objection) as an expert in child forensic interviewing. She gave generalized testimony about interview structure, suggestibility, and indicia of coaching. A juror later asked whether either child’s behavior during Grimm’s interviews was consistent with interviews where coaching was present. Over defense objection that the question solicited improper credibility-vouching, the trial court permitted the question, and Grimm answered that she did not see “huge red flags” indicating coaching because both children provided “very specific experience-based details.”

The Colorado Court of Appeals (split division) concluded the “no signs of coaching” testimony was inadmissible but affirmed on the ground that the defense opened the door by persistently advancing a coaching-by-grandmother theory. The Colorado Supreme Court affirmed, assuming (without deciding) the testimony was inadmissible, and holding that the defense opened the door to that limited expert response.

2. Summary of the Opinion

3. Analysis

3.1. The Legal Rule Clarified (and the Issue the Court Avoided)

The Court deliberately did not decide whether “no indication of coaching” testimony is admissible in the first instance under Colorado evidence law. It assumed inadmissibility because the People did not cross-petition the court of appeals’ inadmissibility ruling and because the granted question focused on door-opening. The majority flags that Colorado doctrine on the boundary between impermissible vouching (often analyzed under CRE 608(a)) and permissible expert context testimony (often analyzed under CRE 702) is “more nuanced” than some divisions have treated it.

Instead, the operative precedent emerging from 2026 CO 23 is about door-opening: when a party persistently advances a specific coaching narrative (particularly one tied to an identifiable person and supported by elicited testimony), a limited expert response that the interviewer observed no indicia of coaching may be admitted (assuming it would otherwise be inadmissible) to correct a misleading impression and prevent unfair advantage.

3.2. Precedents Cited and Their Influence

A. “Opening the door” / “curative admissibility” foundations

• 1 Kenneth S. Broun et al., McCormick on Evidence § 57 (quoting Warren Live Stock Co. v. Farr, 142 F. 116, 117 (8th Cir. 1905)): The majority begins with the classic equitable rationale: a party who “induces” a forbidden inquiry cannot complain when the opponent uses the same opening. This frames door-opening as a fairness doctrine rather than a technical evidentiary exception.
• Bearint ex rel. Bearint v. Dorel Juv. Grp., Inc., 389 F.3d 1339, 1349 (11th Cir. 2004): Cited to show the doctrine’s national recognition under multiple labels (“curative admissibility,” “opening the door,” “fighting fire with fire”).
• People v. Melillo, 25 P.3d 769, 775 (Colo. 2001): Establishes Colorado’s label and general acceptance of the doctrine; supports the majority’s premise that Colorado employs door-opening as a corrective measure.
• Hemphill v. New York, 595 U.S. 140, 152 (2022): Used to describe one articulation: correcting a “misleading impression” based on the “context of the full record.” The majority treats Colorado as “largely speak[ing] the same language” as New York when assessing misleading impressions.
• People v. Murphy, 919 P.2d 191, 195 (Colo. 1996) and Golob v. People, 180 P.3d 1006, 1012 (Colo. 2008): These anchor Colorado’s operative standard: selectively presenting facts that, without context, create an “incorrect or misleading impression” and risk “unfair advantage.” Golob supplies the analytic template the majority applies: when one side’s presentation prevents the jury from hearing the “full context,” door-opening can allow otherwise inadmissible corrective evidence.
• People v. Miller, 890 P.2d 84, 98–99 (Colo. 1995): Reinforces the doctrine’s purpose—preventing unfair advantage—and cautions against imprecise invocation of “opening the door” where standard evidentiary rules suffice.

B. The coaching/vouching line (admissibility background the majority flagged but did not decide)

• People v. Bridges, 2014 COA 65, ¶ 16, 410 P.3d 512, 514–15 and People v. Heredia-Cobos, 2017 COA 130, ¶ 17, 415 P.3d 860, 864: The court of appeals relied on these to deem “no coaching” testimony inadmissible as tantamount to vouching. The Colorado Supreme Court references them chiefly to explain the procedural posture and to note the admissibility question is “more nuanced” than those cases’ “light analytical touch” suggests.
• Venalonzo v. People, 2017 CO 9, ¶ 67, 388 P.3d 868, 885–86 (Coats, J., concurring in the judgment): Quoted for the proposition that the scope of the “no vouching” rule has “always been somewhat unclear,” supporting the majority’s decision not to treat admissibility as settled.
• People v. Snook, 745 P.2d 647 (Colo. 1987); People v. Wittrein, 221 P.3d 1076 (Colo. 2009); and People v. Gaffney, 769 P.2d 1081 (Colo. 1989); People v. Fasy, 829 P.2d 1314 (Colo. 1992); People v. Cooper, 2021 CO 69, 496 P.3d 430: These are marshaled (in a comparative footnote) to illustrate tension in Colorado doctrine between (i) a stricter CRE 608(a) vouching prohibition and (ii) the admissibility of generalized expert testimony under CRE 702 that may incidentally bolster credibility.
• People v. Relaford, 2016 COA 99, ¶ 30, 409 P.3d 490, 496 and People v. Koon, 724 P.2d 1367, 1370 (Colo. App. 1986): Cited via Cooper for the idea that expert testimony often has some incidental credibility effect, without necessarily becoming improper vouching.
• Liggett v. People, 135 P.3d 725, 732 n.2 (Colo. 2006) and Tippett v. Johnson, 742 P.2d 314, 315 (Colo. 1987): Used to emphasize judicial restraint: the Court declines to decide hypothetical or advisory questions (e.g., whether opening the door could ever permit direct “told the truth” testimony), because Grimm did not expressly say the children “told the truth.”

C. Standards of review and limits on the responsive evidence

• People v. Johnson, 2021 CO 35, ¶¶ 15–16, 486 P.3d 1154, 1158: Provides the review framework: contours of the doctrine are construed de novo, but the trial court’s “opened the door” determination is reviewed for abuse of discretion.
• People v. Coons, 2021 CO 70, ¶ 41, 495 P.3d 961, 969 and People v. Rector, 248 P.3d 1196, 1200 (Colo. 2011): Support the highly deferential abuse-of-discretion standard for admitting expert testimony—reversal only for “manifest” error.
• People v. Cohen, 2019 COA 38, ¶ 23, 440 P.3d 1256, 1262–63 and United States v. Sepulveda, 15 F.3d 1161, 1189 n.24 (1st Cir. 1993): These supply the limiting principle that door-opening is not a license to “come storming through”; the rebuttal must be proportionate—“the width of the opening dictates” the permissible response.

D. Dissent’s precedents (why the dissent considered the testimony impermissible and the doctrine inapplicable)

• People v. Eppens, 979 P.2d 14, 17–19 (Colo. 1999) and People v. Baker, 2021 CO 29, 485 P.3d 1100: Used to reinforce Colorado’s “no opinion on truthfulness on a specific occasion” rule and the principle that credibility determinations belong to the jury.
• Tevlin v. People, 715 P.2d 338 (Colo. 1986) and People v. Oliver, 745 P.2d 222 (Colo. 1987): Historical vouching cases emphasizing that even experience-based opinions about whether a child is telling the truth are improper.
• Medina v. People, 291 P.2d 1061 (Colo. 1956); People v. Cole, 654 P.2d 830 (Colo. 1982); People v. Tenorio, 590 P.2d 952 (Colo. 1979); People v. Sams, 685 P.2d 157 (Colo. 1984); People v. Miller, 890 P.2d 84 (Colo. 1995); Golob v. People, 180 P.3d 1006 (Colo. 2008): The dissent frames these as the “true” door-opening lineage: the doctrine applies when a party creates an objectively misleading inference and prevents effective explanation or rebuttal. It argues Lopez did neither because he advanced a credibility-based defense and did not block the People’s ability to rebut with admissible evidence.
• People v. Ray, 2025 CO 42M, 575 P.3d 400; People v. Kembel, 2023 CO 5, 524 P.3d 18; People v. Dist. Ct., 785 P.2d 141 (Colo. 1990): Cited to underscore limits: door-opening prevents prejudice, it cannot be used to “inject prejudice,” and unfair prejudice includes encouraging decisions on improper bases—especially in credibility-driven cases.
• Pernell v. People, 2018 CO 13, 411 P.3d 669 and Davis v. People, 2013 CO 57, 310 P.3d 58: Used to argue that statements in voir dire/opening/closing are not evidence and should not “open the door” to otherwise inadmissible evidence.

3.3. Legal Reasoning (Majority vs. Dissent)

A. Majority’s reasoning: “misleading impression” + “unfair advantage”

The majority’s doctrinal move is straightforward: if the defense repeatedly advances a specific coaching narrative—supported by elicited testimony and framed as the causal explanation for the allegations—then excluding a narrowly responsive expert opinion that the interviewer observed no indicia of coaching would leave the jury with a one-sided, potentially misleading picture. The “coin” metaphor in the opinion captures this: the defense presented one side (coached allegations), so fairness permitted the other side (the interviewer’s observed lack of coaching indicators).

Key factual predicates the majority relies on include:

• Pervasiveness: the defense introduced the coaching theme in voir dire, opening statement, examinations, and closing.
• Specificity: the defense tied coaching to an identifiable person (the maternal grandmother) and a concrete motive (custody).
• Record support: cross-examinations elicited admissions about discussions with grandmother before the forensic interviews, children’s preferences to live with grandmother, timing of disclosures relative to custody turmoil, and delayed reporting.
• Context: Grimm had already given generalized expert testimony about coaching indicators; the juror question sought application of that general framework to the facts.

The majority also treats the narrowness of the response as critical: Grimm did not opine “they told the truth”; she answered the limited question whether she observed indicia of coaching, and the trial court did not allow the People to “weaponize” the opening.

B. Dissent’s reasoning: credibility is for the jury; a coaching defense is not “misleading” evidence

The dissent sees the case as an impermissible end-run around the vouching prohibition: “not coached” is functionally equivalent to “truthful,” particularly where the expert explained coaching as inducing a child to say something that did not happen. In a case that “hinges on credibility,” the dissent warns, such testimony invites jurors to offload credibility judgments onto an expert.

On door-opening, the dissent insists the doctrine should apply only where a party creates an objectively misleading inference and prevents rebuttal or contextual correction. It argues Lopez did neither: he pursued a typical credibility-based theory and the prosecution remained free to rebut with admissible evidence and redirect examination. It also criticizes the majority for treating voir dire and argument as door-opening triggers, including the logical problem of closing arguments “opening the door” after the close of evidence.

3.4. Impact

A. Practical effects in child sexual-assault prosecutions

• Expanded door-opening risk when advancing a “coaching” defense: Defendants who repeatedly attribute allegations to coaching by a specific individual may now face admission (assuming inadmissible) of limited expert testimony that the interviewer observed no indicia of coaching.
• Increased importance of trial strategy calibration: The opinion emphasizes that “mere credibility attacks” do not open the door, but persistent, specific coaching narratives can. Defense counsel must consider whether and how to develop a coaching theory—especially through witness examinations that generate a record of “selective presentation” concerns.
• Juror-question dynamics: The case illustrates how generalized expert testimony can naturally invite juror requests for case-specific application. Trial courts may see more disputes about whether juror questions are seeking impermissible vouching versus permissible application of expert frameworks.

B. Doctrinal effects in Colorado evidence law

• Door-opening clarified, admissibility unresolved: The Court leaves open whether “no coaching” testimony is categorically inadmissible. Future cases may squarely address the CRE 608(a) vs CRE 702 boundary flagged by the majority’s discussion of Snook, Wittrein, Gaffney, Fasy, Venalonzo, and Cooper.
• Reinforced proportionality constraint: The Court’s “width of the opening” admonition, backed by People v. Cohen and United States v. Sepulveda, provides a litigable limiting principle for future trial rulings: even when a door is opened, the response must be tightly cabined to the misleading impression.

4. Complex Concepts Simplified

• “Opening the door” (curative admissibility): A fairness doctrine allowing otherwise inadmissible evidence when needed to correct a misleading impression created by the opponent’s selective presentation. It is not a general “rebuttal” concept; it is a corrective one.
• Vouching: Testimony (often from an expert or authority figure) that effectively tells the jury “this witness is telling the truth” about a specific event. Colorado generally prohibits this because credibility determinations are the jury’s job.
• CRE 608(a) vs. CRE 702:
  • CRE 608(a) governs opinion/reputation evidence about a witness’s character for truthfulness; it forbids opinions about truthfulness on a specific occasion.
  • CRE 702 governs expert testimony that helps the jury understand evidence. Colorado permits generalized expert explanations of behaviors (e.g., trauma responses), even if they incidentally bolster credibility—so long as the expert does not cross into deciding who is truthful about the charged act.
  The unresolved question flagged by the majority is where “no indicia of coaching” falls on that spectrum.
• Unfair prejudice: Evidence can be damaging yet still admissible; “unfairly prejudicial” evidence tends to prompt decisions on improper bases (e.g., deference to an expert’s credibility judgment rather than jurors’ own evaluation).
• Abuse of discretion / manifest error: Appellate courts generally defer to trial judges’ evidentiary calls. Reversal requires showing the ruling was “manifestly erroneous,” not merely debatable.

5. Conclusion

Lopez v. People (2026 CO 23) is a door-opening case more than an expert-vouching case: the Court affirms on the theory that, even assuming the expert’s “no indication of coaching” testimony was inadmissible, the defense opened the door by repeatedly and specifically alleging coaching by the children’s grandmother to achieve custody-related ends. The Court simultaneously cautions that door-opening must be narrowly applied and that responsive evidence must be proportionate to the opening.

The dissent warns that the majority’s application risks converting a common credibility defense into a trigger for expert credibility opinions in precisely the kinds of cases where credibility is most decisive. Going forward, the opinion’s practical significance will lie in how trial courts draw (1) the line between “mere credibility attack” and “selective, misleading coaching narrative,” and (2) the line between a narrow corrective response and impermissible vouching—both under the rubric that the “width of the opening dictates” the permissible rebuttal.