The U.S. Supreme Court heard arguments this week in a case that could decide whether a Texas death row inmate gets a second chance to prove he is intellectually disabled and therefore ineligible for execution. Dexter Johnson, convicted of capital murder and sentenced to death in 2007, argues that updated psychiatric standards make a claim available to him now that was not available when his first appeals began that same year.
The case, Guerrero v. Johnson, centers on whether Johnson can pursue a second federal habeas review under a narrow legal exception. As the Washington Examiner reports, federal law typically allows death row inmates only one round of post-conviction appeals over their sentences, but an exception permits a second appeal if it relies on a new constitutional rule that was previously unavailable. Johnson contends the 2002 ruling in Atkins v. Virginia, which found it unconstitutional to execute intellectually disabled people, only became usable for his case once the American Psychiatric Association revised its diagnostic framework.
How the Diagnostic Shift Changed Johnson's Case
According to SCOTUSblog, the DSM-5, published in May 2013, de-emphasized rigid IQ cutoffs and recognized that someone scoring above 70 could still be intellectually disabled. Texas's highest criminal court adopted that standard in 2018, the outlet notes. In April 2019, an expert tested Johnson's IQ at 70, and a second expert agreed he met the DSM-5's criteria for intellectual disability, per the same account.
Johnson's attorneys say that shift, not the underlying constitutional rule, is what opened the door. “What changed was the framework that made Atkins capable of protecting him,” his legal team argued, according to SCOTUSblog. Texas countered that the claim does not actually rely on a change in law at all, telling the court that “Johnson's Atkins claim does not rely on a change in the law” because Atkins predated his initial habeas application by years.
Lower Courts Sided With Johnson Before Texas Appealed
A federal district court found Johnson's Atkins claim had been previously unavailable and stayed his execution. The U.S. Court of Appeals for the 5th Circuit affirmed that decision in July 2025, and the full appeals court later declined to rehear the case by a vote of 9-7, SCOTUSblog reports. That outcome prompted Texas officials, with support from the Department of Justice, to appeal to the Supreme Court, according to the Washington Examiner.
Under 28 U.S.C. § 2244, a previously unraised claim in a second federal habeas application may proceed only under specified exceptions, including reliance on a new constitutional rule made retroactive by the Supreme Court that was previously unavailable, according to the statute's text as published by Cornell Law School. That narrow exception is the legal hinge on which Johnson's entire case turns.
Justices Press Both Sides on Timing
During arguments, justices pressed Johnson's lawyer, Jeremy Schepers, on whether Atkins was already a usable rule when Johnson filed his first round of appeals in 2007, as detailed by the Denver Gazette. Schepers responded that Atkins remained new enough, based on the character of the 2002 decision itself, to support Johnson's current claim.
Justice Sonia Sotomayor pushed on the logic from the other direction, questioning why the APA's updated intellectual-disability framework would not count as giving Johnson a previously unavailable claim. If the claim was unavailable during Johnson's first habeas petition because it was not yet ripe, she asked, why would it not be ripe now, per the Denver Gazette's account of the arguments. Justice Brett Kavanaugh raised a related concern about future cases, asking whether evolving standards and facts would allow additional reviews every time the American Psychiatric Association releases a new edition of its manual, such as a future DSM-6 or DSM-7.
Texas's attorney, William Peterson, argued that the new APA standards do not create a new constitutional rule that would permit Johnson a second review. He maintained that Johnson could have raised an intellectual-disability claim earlier because Atkins predated his conviction, making him ineligible for the kind of second review he is now seeking.
A Similar Case Ended Without Resolution
The justices have grappled with Atkins-related timing questions before. In Hamm v. Smith, the Supreme Court dismissed a similar Atkins case after hearing oral argument, declining to resolve it, according to SCOTUSblog. Separately, in Moore v. Texas, a habeas court applied current medical standards in concluding that the inmate in that case was intellectually disabled and therefore ineligible for the death penalty, according to the Supreme Court's own opinion in that matter.
Forecasts for when the justices will rule in Johnson's case vary. The Washington Examiner reports the Court could issue a ruling as soon as early 2027 or as late as the end of June 2027, while SCOTUSblog states the decision is expected by late June or early July. The Supreme Court's current term is expected to run through the end of June 2027, and the justices are set to hear arguments next month in several other high-profile cases, including disputes over assault-weapons bans and President Donald Trump's third-country deportation policy, per the Denver Gazette.
