Mercer v. Stewart: Omitted Defense-of-Others Instructions Are Mixed Questions Governed by AEDPA § 2254(d)(1), and Habeas Relief Is Barred Absent a Clearly Established Supreme Court Right

1. Introduction

Case: Barbara Mercer v. Anthony Stewart, Nos. 24-1707/1751 (6th Cir. Apr. 2, 2026).
Court: United States Court of Appeals for the Sixth Circuit.
Posture: Cross-appeals from a federal habeas decision under 28 U.S.C. § 2254 challenging Michigan convictions.

A Michigan jury convicted Barbara Jean Mercer of two counts of second-degree murder, tampering with evidence, and third-degree arson after two drug dealers—Anthony Hannah and Shemel Thomas—were shot and later found dead inside a burned vehicle. Mercer was tried alongside her boyfriend Richard “Ricky” Janish, who admitted shooting both victims but offered accounts sounding in self-defense (as to Hannah) and defense of others (as to Thomas).

Mercer sought federal habeas relief on three principal grounds:

  • Jury instructions: due process violation because the state court refused a defense-of-others instruction for Thomas’s killing.
  • Ineffective assistance:duress (unavailable for homicide under Michigan law) allegedly destroyed counsel’s credibility.
  • Prosecutorial misconduct:

The federal district court granted habeas relief on the jury-instruction claim (Thomas’s murder), but denied the remaining claims. The Sixth Circuit reversed the grant of relief and affirmed denial of all other grounds.

2. Summary of the Opinion

The Sixth Circuit held that AEDPA barred relief on Mercer’s “omitted defense-of-others instruction” claim because:

  1. The state court’s determination that the evidence did not warrant a defense-of-others instruction is a mixed question (law applied to facts), reviewed under § 2254(d)(1), not § 2254(d)(2).
  2. Under Keahey v. Marquis, there is no “clearly established” Supreme Court rule requiring self-defense (or defense-of-others) instructions; therefore Mercer cannot satisfy § 2254(d)(1).

The court also rejected Mercer’s ineffective-assistance claim under the doubly-deferential Strickland/AEDPA standard, and rejected the prosecutorial-misconduct claim under the highly general “fundamental unfairness” standard and the curative-instruction framework reflected in Supreme Court precedent.

3. Analysis

3.1. Precedents Cited

A. AEDPA framework and “clearly established” law

  • Burt v. Titlow and Harrington v. Richter: The court foregrounded AEDPA’s “formidable barrier” and the requirement that a petitioner show an error “beyond any possibility for fairminded disagreement.” These cases set the opinion’s tone: even persuasive arguments on the merits do not suffice unless they fit within AEDPA’s narrow gates.
  • Bergman v. Howard: Central to the opinion’s categorization move. Bergman is used to emphasize that “mixed questions” generally fall within § 2254(d)(1)—a pivotal step because Mercer’s strongest path to relief depended on re-framing the dispute as an unreasonable factual determination under § 2254(d)(2).
  • Carter v. Bogan and Davis v. Lafler: Cited for the “highly deferential” factual-review standard and the presumption of correctness for state factfinding, reinforcing why § 2254(d)(2) is difficult to satisfy even when available.

B. What bucket does an “instruction warranted by evidence” question go in?

  • McMullan v. Booker: The Sixth Circuit leaned heavily on McMullan for the proposition that the “decision about whether to provide a jury instruction” is not the kind of fact determination scrutinized under § 2254(d)(2). This supported the holding that Mercer’s claim belongs in § 2254(d)(1).
  • Moore v. Mitchell and Barnes v. Elo: Reinforced the circuit’s long-standing approach to mixed questions under AEDPA.
  • U.S. Bank Nat. Ass'n ex rel. CWCapital Asset Mgmt. LLC v. Vill. at Lakeridge, LLC and Guerrero-Lasprilla v. Barr: Though arising in other contexts, these were cited to corroborate the broader doctrinal point: applying law to historical facts often produces a mixed question.
  • Lambert v Blodgett: Not adopted, but discussed to explain the district court’s approach (separating legal conclusions from underlying factual determinations). The Sixth Circuit declined to endorse that framework and, in any event, concluded the district court mischaracterized what the state court did.

C. When state courts “ignore” evidence vs. weigh it

  • Brumfield v. Cain and Wofford v. Woods: Used as contrasts—cases where a state court ignored record evidence. The Sixth Circuit distinguished Mercer’s case, emphasizing that the Michigan Court of Appeals did recount and evaluate the key facts Mercer relied upon.
  • Klein v. Martin: Supported the point that state courts need not address every piece of evidence in detail, and federal courts cannot impose “mandatory opinion-writing standards.”

D. The “no clearly established right to a self-defense instruction” barrier

  • Keahey v. Marquis: The controlling obstacle. Keahey held that the Supreme Court has not clearly established a constitutional right to a self-defense instruction; thus habeas relief cannot be granted under § 2254(d)(1) for failure to give one. Mercer conceded Keahey foreclosed § 2254(d)(1), and the panel treated that concession as decisive.
  • Dowling v. United States: Cited (via Keahey) for the “fundamental fairness” concept in due process analysis of trial errors, but the Sixth Circuit emphasized the Supreme Court has not applied that concept to mandate self-defense instructions.
  • Gilmore v. Taylor: A key limiting precedent. The opinion quotes the thrust: the right to present a defense does not expand into a right to have the jury instructed on it in a way that would nullify the general rule that state-law instructional errors are not typically cognizable on federal habeas.
  • Estelle v. McGuire: Reinforced the boundary between state-law instructional mistakes and federal habeas relief: “federal habeas corpus relief does not lie for errors of state law.”

E. De novo review, Teague, and “new rules” in habeas

  • Rice v. White: Cited for the proposition that if § 2254(d) is overcome, review can become de novo. The Sixth Circuit used this to clarify a crucial misconception: de novo review removes AEDPA deference, but does not repeal other habeas constraints.
  • Teague v. Lane, Edwards v. Vannoy, Horn v. Banks, and Williams v. Taylor: These cases anchored the reminder that federal courts cannot announce and retroactively apply “new rules” on habeas, and that AEDPA and Teague are distinct inquiries. The court flagged (without deciding) that recognizing a new federal right to a defense-of-others instruction could implicate Teague.
  • Caspari v. Bohlen: Cited to note that courts may decline to apply Teague if the State does not press it; the panel explained it would not decide Teague here.

F. Ineffective assistance of counsel

  • Strickland v. Washington and Harrington v. Richter: Provided the familiar deficiency/prejudice test and the “doubly deferential” habeas posture. The Sixth Circuit framed Mercer’s burden as showing that no fair-minded jurist could agree with the state court’s no-prejudice determination.
  • White v. Plappert: Used for the “doubly deferential gauntlet” formulation in modern Sixth Circuit habeas practice.
  • English v. Romanowski: Mercer’s comparator. The panel distinguished it: English involved an unfulfilled promise about specific testimony and lacked the kind of shared judicial/prosecutorial correction present here.
  • Thompson v. Rapelje: Supported reliance on juries following corrective or “ameliorative” instructions.
  • Delaware v. Van Arsdall: Invoked for the maxim that the Constitution promises a fair trial, not a perfect one.

G. Prosecutorial misconduct

  • Parker v. Matthews and Trimble v. Bobby: The court relied on Parker to emphasize the “very general” due process standard and the resulting “leeway” for state courts. Trimble underscored the AEDPA requirement for fact-context-specific Supreme Court guidance to deem a state decision unreasonable.
  • Darden v. Wainwright and Donnelly v. DeChristoforo: Functioned as guardrails: even more inflammatory arguments did not compel Supreme Court relief, and curative instructions matter. The panel used these cases to demonstrate why Mercer could not show the Michigan decision was an unreasonable application of clearly established federal law.
  • People v. Buckley: A state authority cited by the Michigan Court of Appeals for the permissibility of argument about credibility; the Sixth Circuit referenced it as part of explaining why the state court saw the remarks as isolated and credibility-focused.
  • Stewart v. Trierweiler: Cited in describing Darden, reinforcing how high the bar is for due process relief based on argument.

H. State-law self-defense/defense-of-others standards (background context)

  • People v. Guajardo, People v. Leffew, and People v. Lemons: These framed Michigan’s “some evidence” requirement and the “not a heavy one” burden to get an instruction. Importantly, the Sixth Circuit treated disputes about whether Mercer met this state-law threshold as (at most) state-law error, not a federal habeas entitlement.
  • Mich. Comp. Laws Ann. § 780.972(1): The Michigan Self Defense Act’s “honestly and reasonably believes” standard for deadly force, including to prevent imminent sexual assault of oneself or another.

3.2. Legal Reasoning

A. The opinion’s core move: classifying the claim under the correct AEDPA subsection

The district court granted habeas relief by treating the Michigan Court of Appeals’ statement—“[t]here was no evidence that Janish acted out of fear that defendant was in imminent danger”—as an unreasonable factual determination reviewable under § 2254(d)(2). The Sixth Circuit rejected that premise.

The panel reasoned that the state court did not decide a “what happened?” question. Instead, it accepted the historical facts (texts, statements, circumstances) and applied a legal threshold (“some/sufficient evidence”) to decide whether the instruction was warranted. That is a classic mixed question and therefore belongs under § 2254(d)(1).

The panel also gave a charitable, AEDPA-consistent reading of the state court’s phrasing. “No evidence” was treated as shorthand for “not enough evidence to meet the legal standard,” especially because the Michigan Court of Appeals had actually recited the facts Mercer relied on and explained why it deemed them insufficient (e.g., Thomas was an unarmed invitee; Mercer later described a non-aggressive push; threats were temporally remote).

B. Once in § 2254(d)(1), Keahey forecloses relief

After categorizing the claim under § 2254(d)(1), the panel applied Keahey v. Marquis. Under Keahey, the Supreme Court has not clearly established that due process requires a self-defense instruction; thus, a state court’s refusal to give one cannot be “contrary to” or an “unreasonable application” of clearly established Supreme Court law.

Mercer conceded this point: Keahey “eliminated 28 U.S.C. § 2254(d)(1) as a viable legal theory.” That concession, paired with the panel’s classification holding, resolved the jury-instruction claim.

C. De novo review does not authorize new constitutional rights on habeas

The opinion adds an important methodological clarification: even if a petitioner clears AEDPA’s deference gate and obtains de novo review (e.g., by satisfying § 2254(d)(2)), federal habeas courts still cannot create and retroactively apply “new rules.” That limitation arises from Teague v. Lane and its progeny.

The panel did not decide Teague’s application here, but its warning directly targets the district court’s reliance on non-Supreme Court authorities (other circuits and states) to recognize a purported due process right to a defense-of-others instruction—an approach that risks announcing precisely the sort of “new rule” Teague prohibits.

D. Ineffective assistance: no Strickland prejudice under AEDPA

Mercer’s ineffective-assistance theory focused on counsel’s early misstep: telling jurors duress would apply, then abandoning it after learning duress is unavailable for homicide under Michigan law. The panel assumed error but found no unreasonable state-court decision on prejudice because:

  • Counsel still pursued a coherent, lawful theory: Mercer lacked the requisite mens rea and intended only to “scare” the victims.
  • The reputational damage was not unique to defense counsel; the prosecutor told jurors the judge and all attorneys shared responsibility for the initial mistake.
  • The court issued a direct corrective instruction that duress was “inapplicable” and must not be considered.

Distinguishing English v. Romanowski, the panel emphasized the correction and shared blame here (and the absence of a singular, defense-only credibility collapse).

E. Prosecutorial misconduct: misstatement of hearsay law did not render trial fundamentally unfair

The prosecutor incorrectly suggested that admissions against interest are “inherently believable” while self-serving statements are “inherently unbelievable” and barred by hearsay. The Michigan Court of Appeals agreed it was inappropriate.

But under Parker v. Matthews’ general standard—improper comments violate due process only if they “so infected the trial with unfairness” as to deny due process—the Sixth Circuit held the state court had ample room to conclude no constitutional violation occurred, especially given:

  • the isolated nature of the remarks within a broader credibility argument,
  • curative instructions that lawyer argument is not evidence and that the jury assigns weight to statements, and
  • the verdict’s apparent inconsistency with the prosecutor’s urged skepticism (the jury rejected first-degree murder, suggesting it credited some defense-favorable statements).

The panel treated Darden v. Wainwright and Donnelly v. DeChristoforo as demonstrating that even serious closing-argument improprieties frequently do not meet the “fundamental unfairness” threshold, particularly where the court instructs jurors properly.

3.3. Impact

This decision’s practical significance lies less in substantive self-defense doctrine and more in federal habeas method:

  1. Reinforced channeling to § 2254(d)(1): Challenges alleging that evidence warranted a state-law defense instruction are strongly characterized as mixed questions, limiting petitioners’ ability to recast such disputes as unreasonable factual determinations under § 2254(d)(2).
  2. Expanded functional reach of Keahey: By treating defense-of-others as within the same “no clearly established right to a self-defense instruction” logic, the decision makes clear that instruction-omission claims in this family are extraordinarily difficult to litigate in federal habeas within the Sixth Circuit.
  3. Teague reminder aimed at district courts: The court’s discussion signals that district courts should not treat “de novo review” as permission to recognize novel due process rights in the jury-instruction arena by borrowing from non-Supreme Court sources.
  4. High tolerance for curative instructions under AEDPA: On both ineffective assistance (duress correction) and prosecutorial misconduct (hearsay misstatement), the decision reaffirms that curative instructions often defeat a claim that the trial was fundamentally unfair—especially under AEDPA’s deference.

4. Complex Concepts Simplified

  • AEDPA (§ 2254): A federal habeas statute requiring strong deference to state-court decisions. Even if a federal judge thinks the state court was wrong, relief is unavailable unless the state court was unreasonably wrong under strict statutory criteria.
  • § 2254(d)(1) vs. § 2254(d)(2):
    • (d)(1): focuses on unreasonable applications of clearly established Supreme Court law.
    • (d)(2): focuses on unreasonable determinations of facts based on the state-court record.
    The Mercer court held that deciding whether evidence is enough to require a jury instruction is generally a (d)(1) “law application” question.
  • Mixed question (law applied to facts): Accepts historical facts as given and asks whether those facts satisfy a legal standard (here, whether there was “some evidence” warranting a defense instruction).
  • “Clearly established” law: Only Supreme Court holdings count. Lower-court decisions—even unanimous ones—cannot create “clearly established” federal law for AEDPA purposes.
  • Teague “new rule” bar: Even if AEDPA deference drops away, habeas courts generally cannot announce new constitutional rules and apply them retroactively to finalized convictions.
  • Defense-of-others instruction: A jury instruction allowing acquittal if the defendant used force reasonably and honestly believed necessary to protect another person from imminent death, great bodily harm, or sexual assault (as defined by state law here, Mich. Comp. Laws § 780.972(1)).
  • Strickland prejudice: It is not enough to show counsel erred; the defendant must show a reasonable probability the result would have been different without the error.
  • Prosecutorial misconduct (due process standard): Improper argument violates the Constitution only when it makes the whole trial fundamentally unfair; courts heavily weigh context and the judge’s instructions.

5. Conclusion

Mercer v. Stewart is a forceful reaffirmation of AEDPA’s gatekeeping function for jury-instruction claims. The Sixth Circuit held that whether evidence warranted a defense-of-others instruction is a mixed question governed by § 2254(d)(1), not a factual dispute under § 2254(d)(2). Once placed in the correct AEDPA category, Keahey v. Marquis effectively foreclosed relief because the Supreme Court has not clearly established a constitutional right to a self-defense (or defense-of-others) instruction.

Beyond the instruction issue, the opinion underscores two broader themes in habeas practice: (1) Strickland claims rarely succeed under AEDPA absent clear outcome-determinative prejudice, especially where the trial court issues corrective instructions; and (2) prosecutorial-misconduct claims face a particularly steep hill because the governing due process standard is general and heavily context-dependent.

The decision’s lasting significance is methodological: it tightens the doctrinal routing of instruction-omission disputes into § 2254(d)(1) and cautions that even “de novo” post-AEDPA review does not permit the creation of new constitutional rules on federal habeas.