COA Requires Developed, Issue-Specific Argument; Prosecutorial “Vouching” Not Clearly Established as a Standalone Due Process Violation under AEDPA — Revilla v. Harpe (10th Cir. 2025)

Introduction

In Revilla v. Harpe, No. 25-6031 (10th Cir. Oct. 31, 2025) (nonprecedential order), the Tenth Circuit denied a certificate of appealability (COA) to a state prisoner who sought to appeal the federal district court’s denial of his 28 U.S.C. § 2254 habeas petition. The case arises from an Oklahoma conviction for two counts of lewd molestation and one count of forcible sodomy of a victim under sixteen, with consecutive twenty-year sentences on each count. The Oklahoma Court of Criminal Appeals (OCCA) affirmed on direct appeal, and state post-conviction efforts were unsuccessful.

In federal habeas proceedings, a magistrate judge initially recommended relief on one sub-argument under a prosecutorial-misconduct ground—asserted improper vouching for the victim’s credibility. The district court rejected that recommendation and later denied all remaining claims, some on waiver (failure to object to the supplemental report and recommendation), and others on the merits. On appeal, the Tenth Circuit confined its review to the sole properly preserved sub-argument: whether the prosecutor impermissibly vouched for the victim, C.D., thereby rendering the trial fundamentally unfair.

Two rulings define the order’s practical importance. First, the court underscores the rigorous COA standard under Slack v. McDaniel and the petitioner’s obligation to develop an argument that directly engages the district court’s reasoning; merely repeating earlier habeas briefing will not suffice. Second, the court reiterates that there is no clearly established Supreme Court authority holding that “improper vouching,” standing alone, constitutes a constitutional violation for AEDPA purposes; therefore, relief must rest on the broader, general due process unfairness standard and deference to the state court’s merits adjudication.

Summary of the Opinion

The Tenth Circuit (Judges McHugh, Moritz, and Carson) denied the COA and dismissed the appeal. Applying 28 U.S.C. § 2253(c)(2) and Slack v. McDaniel, the panel concluded that Mr. Revilla failed to demonstrate that reasonable jurists could debate the district court’s assessment of his sole properly preserved claim (prosecutorial misconduct via impermissible vouching).

Because defense counsel did not object contemporaneously at trial, the OCCA reviewed for plain error and concluded the prosecutor neither personally vouched for the victim nor cumulatively deprived Revilla of a fair trial. The federal district court, reviewing under AEDPA, determined there is no clearly established Supreme Court law that improper vouching itself violates the Constitution, and alternatively held that, even under the general due process standard (trial unfairness), the OCCA’s resolution was reasonable in light of the record. The Tenth Circuit found that Revilla’s opening brief largely copied his habeas petition, did not confront the district court’s reasons, and offered only a conclusory assertion that the issue is “debatable among reasonable jurists.” On that basis, the court denied a COA “for substantially the same reasons” as the district court.

The panel also noted that only the “improper vouching” sub-argument was properly before it. Revilla forfeited the remaining sub-arguments under his prosecutorial-misconduct ground (eliciting propensity evidence, suggesting facts outside the record, and invoking sympathy) by failing to object to the magistrate judge’s supplemental report and recommendation—triggering the Tenth Circuit’s “firm waiver rule.”

Analysis

Precedents and Authorities Cited

• Slack v. McDaniel, 529 U.S. 473, 484 (2000): Establishes that a COA issues only if the applicant makes a substantial showing of the denial of a constitutional right; this means showing that reasonable jurists would find the district court’s resolution of the constitutional claim debatable or wrong. Slack frames the threshold COA inquiry and is the backbone of the panel’s approach.
• 28 U.S.C. § 2254(d)(1) and (d)(2): The AEDPA standards limiting federal habeas relief to state court decisions that are contrary to, or involve an unreasonable application of, clearly established Supreme Court law (d)(1), or that rest on an unreasonable determination of the facts based on the state-court record (d)(2). The panel’s review presupposes that AEDPA deference applies because the OCCA adjudicated the claim’s merits (albeit under plain-error review).
• House v. Hatch, 527 F.3d 1010, 1018 (10th Cir. 2008): Clarifies that the absence of clearly established Supreme Court law is dispositive under § 2254(d)(1). The district court relied on this proposition to reject relief on a standalone “vouching equals constitutional violation” theory.
• Morales-Fernandez v. I.N.S., 418 F.3d 1116, 1119 (10th Cir. 2005): Articulates the Tenth Circuit’s firm waiver rule—failure to object to a magistrate judge’s report and recommendation waives appellate review. The panel used this to narrow the case to the sole preserved sub-argument (improper vouching).
• Fed. R. App. P. 32.1 and 10th Cir. R. 32.1: Though the order is nonprecedential, it may be cited for its persuasive value under these rules; it is binding only under law-of-the-case, res judicata, and collateral estoppel.

Legal Reasoning

1) The COA gatekeeping function. The court begins by restating the COA standard under Slack. A COA is not a merits determination; it is a threshold showing that jurists of reason could debate the district court’s analysis. Where, as here, the district court rejected the claim on the merits under AEDPA, the petitioner must show that reasonable jurists could debate whether the state court’s disposition violated § 2254(d). In practical terms, that requires a focused, issue-specific argument engaging the district court’s actual reasons.

2) AEDPA’s “clearly established law” constraint. The district court held—and the Tenth Circuit accepted for COA purposes—that there is no clearly established Supreme Court authority that “improper vouching,” as a category, is itself a constitutional violation. That conclusion activates House v. Hatch: in the absence of clearly established Supreme Court law on the precise point, relief under § 2254(d)(1) is foreclosed. This does not leave habeas petitioners without a path; they can still argue prosecutorial misconduct under the general due process standard—i.e., whether comments “so infected the trial with unfairness as to make the resulting conviction a denial of due process.” But that path is steep, especially when state courts have already rejected the claim on the merits and AEDPA deference attaches.

3) Application to the vouching claim. The OCCA reviewed the claim for plain error because no contemporaneous objection was lodged at trial. It found no personal vouching and no cumulative unfairness. The district court, in turn, reasoned that the prosecutor “did not express personal belief in C.D.’s credibility or awareness of information withheld from the jury,” but instead “fairly argued that C.D.’s testimony was believable based on the evidence at trial” (Aplt. App. at 79), and that the statements were “a reasonable response to the defense” strategy of labeling the victim a liar (id. at 80). The court also emphasized that the jury was instructed that it alone judged credibility and that counsel’s arguments are not evidence (id. at 82). From the “entirety of the trial proceedings,” the court concluded that the OCCA’s merits determination was not unreasonable (id. at 81–82).

4) The petitioner’s failure to meet Slack. On appeal, the Tenth Circuit found that Revilla’s opening brief essentially duplicated prior filings, did not confront the district court’s reasons, and offered only the bare assertion that the issue is debatable among reasonable jurists. That is not enough. The COA inquiry requires a developed showing that the district court’s assessment—applying AEDPA—could be reasonably debated. The panel therefore denied a COA “for substantially the same reasons stated by the district court.”

5) Waiver of other sub-arguments and grounds. The panel limited its review to the sole preserved sub-argument (improper vouching), noting that Revilla failed to object to the magistrate judge’s supplemental report and recommendation on the remaining sub-arguments (propensity evidence, facts outside the record, sympathy) and separate grounds (other crimes/bad-acts evidence; limiting instruction; ineffective assistance of appellate counsel; and state-jurisdiction challenge). Under Morales-Fernandez, this failure waived appellate review.

Impact and Practical Significance

This order, though nonprecedential, has meaningful persuasive value for habeas practice in the Tenth Circuit and beyond.

• COA briefing must engage the district court’s rationale. Petitioners cannot satisfy Slack by copying and pasting arguments from earlier stages. A COA application should:
  • Identify the district court’s dispositive reasons,
  • Explain why those reasons are debatable among reasonable jurists, and
  • Address AEDPA’s deference and the state court’s reasoning head-on.
  Absent that, the COA will be denied without a merits determination.
• Vouching claims face an AEDPA headwind. Because no Supreme Court decision holds that “improper vouching” is, by itself, a constitutional violation, § 2254(d)(1) relief cannot be grounded on that proposition. Petitioners must instead show that the challenged remarks—viewed in context—rendered the entire trial fundamentally unfair, and that the state court’s contrary conclusion was objectively unreasonable under AEDPA. That is a demanding, case-specific showing.
• Preservation matters at every stage. Failure to object at trial can limit state courts to plain-error review, and failure to object to magistrate judge recommendations can waive federal appellate review entirely. Revilla illustrates both pitfalls: (1) plain-error review at the OCCA stage and (2) waiver of multiple habeas grounds for failing to object to the supplemental report and recommendation.
• Prosecutors may argue credibility from the evidence and in response to defense attacks. The district court’s analysis—accepted at the COA stage—emphasized that the prosecutor did not assert personal beliefs or extra-record knowledge, but argued credibility based on the record and in response to the defense’s theory. Coupled with instructions that arguments are not evidence and that jurors determine credibility, such comments typically will not meet the “fundamental unfairness” threshold in habeas.
• Nonprecedential but citable. Although this order is not binding except under law-of-the-case, res judicata, and collateral estoppel, it may be cited for its persuasive value under Fed. R. App. P. 32.1 and Tenth Cir. R. 32.1. It is a useful reference on how the Tenth Circuit polices the COA gatekeeping function and how AEDPA shapes vouching-based prosecutorial-misconduct claims.

Complex Concepts Simplified

• Certificate of Appealability (COA): A required “ticket to appeal” in habeas cases. To obtain a COA, a petitioner must show that reasonable jurists could debate whether the district court’s assessment of the constitutional claim is correct. It is not enough to think the district court was wrong; one must show that the question is reasonably debatable.
• AEDPA Deference (§ 2254(d)): When a state court decides a claim on the merits, a federal habeas court may grant relief only if the state decision (a) contradicts or unreasonably applies clearly established Supreme Court law (d)(1), or (b) is based on an unreasonable determination of the facts (d)(2). “Clearly established” means holdings of the U.S. Supreme Court—general circuit law does not qualify.
• “Clearly Established” and Vouching: There is no Supreme Court holding that says “improper vouching, by itself, violates due process.” Thus, under AEDPA, relief cannot be premised on that categorical proposition. Instead, courts assess whether the prosecutor’s comments, taken in context, made the trial fundamentally unfair—an analysis guided by Supreme Court due process precedents.
• Improper Vouching: Occurs when a prosecutor conveys a personal belief in a witness’s credibility or implies knowledge outside the trial record (e.g., “I know she’s telling the truth” or “we’ve confirmed it off the record”). By contrast, arguing that a witness is credible based on evidence in the record—and as a response to the defense’s attack—is generally permissible advocacy.
• Plain Error Review (State Court): When a defendant fails to object at trial, appellate courts often review only for “plain error”—an obvious error affecting substantial rights. In habeas, a state court’s plain-error merits review typically still counts as an “adjudication on the merits,” triggering AEDPA deference.
• Firm Waiver Rule (Magistrate Judge Objections): In the Tenth Circuit, if a party does not timely object to a magistrate judge’s report and recommendation, they usually waive appellate review of both factual and legal issues addressed in that report. Objecting preserves issues; silence forfeits them.
• “Cumulative Effect” of Comments: Courts sometimes assess whether the combined effect of multiple prosecutorial comments, even if individually harmless, collectively rendered the trial unfair. The OCCA performed this check and found no due process violation.

Conclusion

Revilla v. Harpe reinforces two core points in habeas practice. First, the COA is a real gatekeeping device: petitioners must write COA applications that grapple with the district court’s reasoning and demonstrate why reasonable jurists could disagree with it under AEDPA’s limits. Repetition of prior arguments, without engagement, is fatal. Second, under § 2254(d)(1), “improper vouching” is not itself a clearly established constitutional violation; habeas relief on such claims must run through the broader due process lens of fundamental unfairness, with heavy deference to state-court adjudications—especially where the prosecutor’s comments are tied to the evidentiary record, responsive to defense attacks, and accompanied by standard jury instructions clarifying that counsel’s statements are not evidence.

Although nonprecedential, the decision offers persuasive guidance for trial lawyers (preserve objections), habeas counsel (preserve objections to magistrate reports; tailor COA briefs to the district court’s reasoning), and prosecutors (argue from the record; avoid personal assurances; heed the “invited response” boundaries). In the AEDPA era, Revilla is a cautionary exemplar: without preservation, targeted briefing, and an argument that meets Slack’s standard within AEDPA’s confines, a COA will not issue.