Changing Forensic Science as a “Factual Predicate” Under AEDPA: Sixth Circuit Authorizes Danny Hill’s Successive Habeas Petition Based on Rejected Bite‑Mark Evidence

Introduction

In a not-for-publication order, a Sixth Circuit panel (Judges Moore, Clay, and Stranch; opinion by Judge Karen Nelson Moore) granted Danny Hill’s motion to file a second or successive federal habeas petition under 28 U.S.C. § 2244(b). The core issue—remanded to the panel by the Sixth Circuit sitting en banc—was whether newly available scientific evidence discrediting bite-mark testimony can satisfy AEDPA’s “gatekeeping” standard for successive petitions.

Hill was convicted and sentenced to death in 1986 for the brutal murder of 12-year-old Raymond Fife. At trial, a forensic odontologist, relying on then-accepted bite-mark identification methodology, opined that a bite on the victim’s penis could only have been made by Hill. Decades later, the scientific foundation for such testimony has collapsed: modern forensic scientists (including former leaders of the American Board of Forensic Odontology, ABFO) now explicitly state that the injury is not a human bite-mark and that the prior methodology cannot reliably identify a specific biter from the general population.

The panel’s order does not decide the merits of Hill’s constitutional claim. Rather, it clarifies two gatekeeping points with broad significance:

At “gate one” (the court of appeals authorization stage), the prima facie standard is lenient.
For § 2244(b)(2)(B)(i), the “factual predicate” may include a post-conviction scientific paradigm shift that reveals the critical trial evidence as false or unreliable.

Summary of the Opinion

The Sixth Circuit authorizes Hill’s successive petition, holding that he made a prima facie showing under both prongs of § 2244(b)(2)(B):

Due diligence/factual predicate (§ 2244(b)(2)(B)(i)): The vital fact underlying Hill’s due-process claim is that the mark on Fife’s penis is not a human bite. That fact could not reasonably have been discovered until scientific standards changed—specifically, after the ABFO’s guideline evolution circa 2013 and the resulting expert consensus repudiating the earlier methodology. Thus, Hill acted with due diligence.
Clear-and-convincing innocence gateway (§ 2244(b)(2)(B)(ii))—prima facie showing only: Hill submitted sufficient allegations and documentation (including expert affidavits) to require further district court analysis of whether, absent the constitutionally infirm bite-mark evidence, no reasonable factfinder would have found him guilty. At this stage, the court does not decide the merits; it only authorizes the district court to undertake that inquiry.

The panel emphasizes that AEDPA establishes “two gates.” Gate one is the circuit court’s authorization based on a lenient prima facie showing. Gate two is the district court’s independent, searching review of the statutory requirements and the merits. The panel distinguishes ripeness (which concerns when the alleged harm occurred) from discovery of the “factual predicate” (which focuses on when the facts making the harm clear were discoverable through due diligence).

Analysis

Precedents Cited and Their Influence

In re Lott (6th Cir. 2004) and Bennett v. United States (7th Cir. 1997): These cases define “prima facie” in the § 2244(b)(3)(C) context as “sufficient allegations of fact together with some documentation” warranting fuller district court exploration. Lott’s “lenient” standard anchors the court’s authorization analysis here.
Tyler v. Cain (U.S. 2001): The Supreme Court explains the critical distinction between the appellate court’s authorization function (prima facie) and the district court’s obligation to determine whether the statutory standard is actually met. The Sixth Circuit leans on this doctrinal separation to keep “gate one” narrow and preliminary.
In re McDonald (6th Cir. 2008): Reinforces that authorization requires only sufficient allegations and some documentation, especially when evaluating § 2244(b)(2)(B)(ii)’s “no reasonable factfinder” prong at gate one.
In re Wogenstahl (6th Cir. 2018): Clarifies that while a claim can be “ripe” at trial (harm occurred), the “factual predicate” for § 2244(b)(2)(B)(i) may be discovered later, such as through post-trial revelations contradicting expert testimony—a parallel to Hill’s situation. The panel cites Wogenstahl to separate ripeness timing from due-diligence discovery.
Ayers v. Ohio Dep’t of Rehab. & Corr. (6th Cir. 2024) and Rivas v. Fischer (2d Cir. 2012): Provide the definition of “factual predicate” as the vital facts underlying the claim—here, the vital fact is that the mark is not a human bite.
Ege v. Yukins (6th Cir. 2007): Confirms that bite-mark testimony can be so substantively and probabilistically unsound as to violate due process. Ege gives doctrinal footing to Hill’s due-process theory.
Bugh v. Mitchell (6th Cir. 2003); Brown v. O’Dea (6th Cir. 2000); Payne v. Tennessee (U.S. 1991); Perry v. New Hampshire (U.S. 2012): These decisions articulate the due-process standard for admission of highly prejudicial or unreliable evidence. The court uses this framework to characterize the modern repudiation of bite-mark identification as potentially rendering Hill’s trial fundamentally unfair.
Goldblum v. Klem (3d Cir. 2007): Emphasizes that appellate authorization does not bind the district court on the merits; the district court must conduct an independent gatekeeping inquiry at gate two.
Rhodes v. Smith (8th Cir. 2020); Feather v. United States (8th Cir. 2021); Case v. Hatch (10th Cir. 2013): The panel acknowledges these cases but limits their relevance. They largely address merits determinations (often at gate two) rather than initial authorization and do not define “factual predicate” under § 2244(b)(2)(B)(i). The Sixth Circuit treats Rhodes’s initial authorization as supportive of allowing Hill through gate one.

Legal Reasoning

1) The Two-Gate Framework and a Lenient Prima Facie Standard

The court begins with AEDPA’s structure:

Gate One (Court of Appeals): The applicant must make a prima facie showing that the successive petition satisfies § 2244(b)(2). This standard is intentionally “lenient,” requiring only sufficient factual allegations plus some documentation. The panel underscores Congress’s directive for expedited, preliminary appellate screening.
Gate Two (District Court): After authorization, the district court independently determines whether the statutory requirements are in fact met and then reaches the habeas claim’s merits, if appropriate. Authorization neither predicts nor dictates the outcome.

2) “Factual Predicate” Includes Post-Conviction Scientific Paradigm Shifts (§ 2244(b)(2)(B)(i))

The state argued the factual predicate was fixed at trial (1986), when the bite-mark evidence was introduced. Hill argued the predicate is the later scientific consensus and guideline change showing that the injury was not a human bite and that the identification methodology lacked scientific basis.

The panel adopts Hill’s framing, drawing on the “vital facts” conception of “factual predicate.” The vital fact is not merely that bite-mark testimony was admitted; it is the later-discovered fact—made knowable only after the 2013 ABFO guideline change and ensuing expert consensus—that there was no human bite-mark and that prior identification claims are scientifically baseless. Because that fact could not have been discovered earlier with due diligence, § 2244(b)(2)(B)(i) is satisfied at the prima facie stage.

The court distinguishes ripeness (when the harm occurred) from discoverability of the factual predicate (when the facts making the harm clear could be found by due diligence). Wogenstahl supports this separation, and the en banc remand explicitly left the “factual predicate” question to the panel.

3) Prima Facie Showing of a Due-Process Violation and the “No Reasonable Factfinder” Gateway (§ 2244(b)(2)(B)(ii))

For the due-process claim, Hill supplied affidavits from modern forensic dentists—including former ABFO leaders—stating that the injury was not a human bite-mark or, at minimum, that the evidence cannot support any conclusion as to causation. The panel notes an Ohio state court also recognized that advances in odontology undermine the trial testimony: experts can no longer identify a specific biter from the open population and the earlier trial opinions are contradicted by current science.

Those submissions are enough, at gate one, to allege a due-process violation where the admission of unreliable, highly prejudicial expert evidence rendered the trial fundamentally unfair—a theory recognized in Ege v. Yukins.

On the “no reasonable factfinder” prong, Hill emphasizes that the state portrayed the bite-mark evidence as especially significant. The state counters that Hill’s own statements to police independently implicated him. The panel does not weigh the evidence; it finds that the bite-mark testimony was a critical pillar at trial and that whether any reasonable juror would convict without it is a question requiring the district court’s gate two analysis. Thus, Hill meets the prima facie threshold for § 2244(b)(2)(B)(ii).

Impact

Although unpublished, the order carries substantial persuasive weight and practical consequences within the Sixth Circuit and beyond:

Scientific Shifts Can Open Gate One: The decision squarely recognizes that later-discovered scientific consensus undermining trial forensics can constitute the § 2244(b)(2)(B)(i) “factual predicate.” This is particularly significant for discredited or sharply limited fields (e.g., bite-mark identification, arson pattern analysis, microscopic hair comparison, certain SBS/AHT theories).
Clear Signal on Bite-Mark Evidence: The order dovetails with a growing institutional retreat from bite-mark identification. It reinforces that convictions materially bolstered by such testimony may warrant renewed federal review, even decades later, when supported by modern expert consensus.
Preserves Rigorous Gate Two Review: Authorization does not imply success on the merits. Petitioners must still establish by clear and convincing evidence that, absent the constitutional error, no reasonable factfinder would have convicted. District courts remain the venue for evidentiary hearings, record-building, and merits assessments.
Guidance for Litigation Strategy: Defense counsel should frame “factual predicate” around the later-discovered scientific fact, not merely the existence of trial testimony. Submissions should include affidavits from recognized experts, references to professional body guideline changes (e.g., ABFO), and, where possible, prior state court recognitions of scientific advancements.
Doctrinal Clarification on Ripeness vs. Discoverability: The opinion cleanly separates when an error occurs (ripeness) from when the “vital fact” revealing that error becomes discoverable. This helps reconcile en banc observations about ripeness with AEDPA’s due-diligence inquiry.
Prosecutorial and Policy Implications: Prosecutors evaluating old cases may anticipate increased successive-petition authorizations when key forensic pillars have been debunked. Offices may proactively review such cases to mitigate litigation risk and address potential miscarriages of justice.

Complex Concepts Simplified

AEDPA: The Antiterrorism and Effective Death Penalty Act regulates federal habeas petitions. For second or successive petitions, AEDPA imposes strict gatekeeping standards in § 2244(b).
Gate One vs. Gate Two: Gate one is appellate authorization based on a lenient “prima facie” showing. Gate two is the district court’s independent, in-depth determination of whether the statutory requirements and the merits are actually satisfied.
Prima Facie (in this context): Sufficient allegations plus some documentation to justify fuller district court exploration; it is not a merits ruling.
Factual Predicate (§ 2244(b)(2)(B)(i)): The vital facts underlying the claim. Here, the vital fact is the modern scientific determination that the injury was not a human bite, which could not be discovered earlier with due diligence.
Clear and Convincing Evidence (§ 2244(b)(2)(B)(ii)): A high standard of proof, requiring a firm belief or conviction—greater than a preponderance but less than beyond a reasonable doubt—that, but for the constitutional error, no reasonable factfinder would convict.
Due Process/Fundamental Fairness: Admission of highly prejudicial and unreliable evidence can render a trial fundamentally unfair, violating the Fourteenth Amendment.
ABFO and Bite-Mark Evidence: The American Board of Forensic Odontology historically promulgated bite-mark standards. Since around 2013, leading odontologists and the ABFO community have retreated from claims that bite-mark analysis can reliably identify a specific biter from the general population; multiple experts in Hill’s case now opine the injury was not a human bite-mark.
Ripeness vs. Discoverability: A claim can be “ripe” at trial (error has occurred), but the “factual predicate” may only become discoverable later when new facts emerge (e.g., scientific repudiation) through due diligence.

Conclusion

The Sixth Circuit’s order in In re: Danny Hill crystallizes an important doctrinal point: post-conviction scientific developments that expose critical trial evidence as false or fundamentally unreliable can serve as the “factual predicate” for authorizing a successive habeas petition under § 2244(b)(2)(B)(i). Combined with the court’s reaffirmation of the lenient prima facie standard and the two-gate framework, the decision facilitates appellate authorization in cases where modern science recasts the evidentiary record.

While the order does not forecast success for Hill at gate two, it underscores that bite-mark testimony—once treated as powerful identification proof—now stands on unstable scientific ground. District courts will remain the crucible for rigorous, evidence-based determinations of whether, absent such tainted evidence, any reasonable factfinder could convict. In the broader legal landscape, Hill’s authorization marks a significant step toward aligning habeas review with contemporary scientific standards, particularly in cases resting on forensic paradigms that have since been discredited.