Supreme Court: Dexter Johnson 8th Amendment Claim on DSM-5 Disability

• Texas death row inmate Dexter Johnson is attempting to challenge his conviction based on updated medical guidelines for intellectual disability.
• The 2013 DSM-5 reclassified Johnson as intellectually disabled, a status he did not meet under earlier diagnostic criteria.
• The Supreme Court is considering whether these evolving medical standards qualify as a "new rule of constitutional law" to allow a successive federal habeas application.
• Conservative justices expressed concerns about judicial finality and the potential for "eternal Atkins claims" if such challenges are permitted.
• Liberal justices argued that the Atkins v. Virginia precedent anticipated the evolution of medical standards for intellectual disability.

The Supreme Court heard oral arguments in Dexter Johnson's case on November 4, 2026, and its deliberations indicate a potential stance against reopening death penalty cases based on evolving medical standards, with a decision yet to be issued.

Dexter Johnson, a Texas death row inmate, is seeking to challenge his conviction based on updated medical criteria for intellectual disability. Johnson was found guilty of murdering Maria Aparece in 2007. At the time of his conviction, the landmark Supreme Court decision in Atkins v. Virginia, which deemed the execution of individuals with intellectual disabilities unconstitutional, had been established for five years. However, Johnson did not initially present a claim of intellectual disability, as his IQ scores of 79 and 88 did not meet the diagnostic thresholds then in place.

Despite expert testimony during his trial indicating that Johnson possessed the intellectual capacity of a 10-year-old and suffered from severe language deficits, placing him in the lowest one percentile of the population, these factors alone were insufficient for a formal diagnosis under the prevailing standards. It was not until six years after his conviction that new guidelines from the American Psychiatric Association's 2013 edition of the Diagnostic and Statistical Manual of Mental Disorders, known as DSM-5, provided a revised framework. These updated criteria moved beyond a sole reliance on IQ scores, acknowledging that individuals with IQs above 70 could still be classified as intellectually disabled, a change that now includes Johnson.

The Supreme Court's ruling in Atkins v. Virginia established a constitutional prohibition against executing individuals with intellectual disabilities, grounding this protection in the Eighth Amendment. However, the application of this standard has been complicated by evolving medical understanding, particularly with the introduction of the DSM-5. This updated manual significantly altered the diagnostic approach to intellectual disability, providing a new lens through which Johnson's condition could be assessed, leading to his current classification as intellectually disabled.

Johnson's attempt to leverage these updated medical standards for a new challenge faces significant legal obstacles, primarily due to the Anti-Terrorism and Effective Death Penalty Act (AEDPA). This federal law severely restricts successive habeas corpus applications, generally permitting only one unless the claim is based on "a new rule of constitutional law made retroactive to cases on collateral review by the Supreme Court that was previously unavailable." Despite these stringent requirements, the Fifth Circuit Court of Appeals determined that Johnson's case met this exception, thereby allowing him to proceed with his successive federal habeas application.

During recent proceedings, the Supreme Court heard oral arguments in Johnson's case, *Guerrero v. Johnson*, on November 4, 2026, and a decision is pending. The conservative majority expressed considerable skepticism regarding whether evolving medical standards for intellectual disability, such as those introduced by the DSM-5, constitute a "new rule of constitutional law" under AEDPA. Justice Brett Kavanaugh voiced concerns about the potential for "eternal Atkins claims and zero finality" if medical definitions are continually evolving, suggesting such an interpretation could lead to endless death penalty challenges. Justice Clarence Thomas questioned whether the two-decade-old Atkins precedent could ever be considered a "new rule," while Justice Amy Coney Barrett drew an analogy to the invention of the telephone, implying that something established long ago cannot be perpetually new.

Conversely, the Court's liberal wing appeared more receptive to Johnson's arguments. Justice Elena Kagan highlighted that the Atkins decision itself acknowledged that the substantive standard for intellectual disability would be largely defined by medical criteria, which are inherently subject to change and evolution. She suggested that fundamental shifts in diagnostic criteria could effectively create an an "Atkins II rule," thereby qualifying as new. Justice Ketanji Brown Jackson further proposed that the Court should consider whether a claim is new to a particular individual, rather than focusing on its general novelty, given the dynamic nature of medical science.

The Supreme Court's deliberations in *Guerrero v. Johnson* indicate a potential stance against reopening death penalty cases based on evolving medical standards, with a decision yet to be issued. This position underscores a judicial preference for finality in convictions, even when confronted with updated scientific understanding of conditions like intellectual disability. For lawyers representing death row inmates, particularly in Texas, this development suggests a narrowing of avenues for post-conviction relief that rely on changes to diagnostic criteria, such as those found in the DSM-5.

This potential ruling emphasizes the formidable challenge of navigating the Anti-Terrorism and Effective Death Penalty Act's restrictions on successive habeas petitions. It suggests that the Court may not view evolving medical standards, even those that fundamentally alter an individual's classification under the Eighth Amendment, as automatically constituting a "new rule of constitutional law" sufficient to overcome AEDPA's strictures. The outcome will likely reinforce the difficulty of mounting death penalty challenges based on evolving medical standards for intellectual disability, prioritizing judicial finality over the integration of updated scientific understanding in these critical cases.

Lawyers representing death row inmates, particularly in Texas, should note the Supreme Court's likely stance against allowing successive habeas petitions based on evolving medical definitions of intellectual disability (e.g., DSM-5 changes) to re-litigate Atkins claims. This signals a narrowing of avenues for post-conviction relief based on updated diagnostic criteria, emphasizing judicial finality over evolving scientific understanding in this context.

Source: Original reporting via Court News Service