Michael Kovac/Getty Images Justice Ruth Bader Ginsburg criticized Texas for clinging to "superseded standards when an individual’s life is at stake.”

The Supreme Court ruled on Tuesday that Texas was wrong to rely on an outdated medical standard to assess the intellectual disability of a defendant facing the death penalty. The decision effectively gives the prisoner, Bobby James Moore, the opportunity to be re-sentenced, most likely to life in prison.

The justices have been raising the bar on the sentencing of people with mental disabilities over the last several years. In a landmark 2002 ruling, the court said the Constitution prohibits states from imposing the death penalty on the intellectually disabled. In 2014, the justices explained that courts determining intellectual disability can’t just rely on rigid metrics and must look to the judgment of medical experts.

Tuesday’s 5-to-3 decision said the factors that the Texas state court considered in weighing Moore’s level of impairment create “an unacceptable risk that persons with intellectual disability will be executed.”

Among other factors, the Texas court had turned to a 1992 manual for assessing mental disabilities, which has since been superseded by a more updated version that takes into account developments in mental health science. The standards adopted by the state court were “wholly nonclinical” and not in accordance with “the medical community’s diagnostic framework,” Justice Ruth Bader Ginsburg wrote for the majority.

The Supreme Court’s decision in Moore v. Texas was based on the Eighth Amendment’s prohibition against cruel and unusual punishment, which has been interpreted to bar the death penalty both for children and for people like Moore, who has an average IQ score of 70.66. Moore, now 57, was convicted of capital murder in 1980.

Texas Department of Criminal Justice Bobby James Moore was convicted of capital murder nearly four decades ago.

Ginsburg noted that Texas couldn’t “satisfactorily explain why it applies current medical standards for diagnosing intellectual disability in other contexts,” such as public education or the juvenile justice system, and “yet clings to superseded standards when an individual’s life is at stake.”

“If the States were to have complete autonomy to define intellectual disability as they wished,” Ginsburg wrote, the 2002 decision exempting the intellectually disabled from execution “could become a nullity, and the Eighth Amendment’s protection of human dignity would not become a reality.”

“States have some flexibility, but not unfettered discretion, in enforcing” the Supreme Court’s prior rulings in this area of law, Ginsburg added.

The decision was joined by Justices Anthony Kennedy, Stephen Breyer, Sonia Sotomayor and Elena Kagan. Chief Justice John Roberts wrote a dissenting opinion, which was joined by Justices Clarence Thomas and Samuel Alito.

The majority’s approach “constitutionalizes rules for which there is not even clinical consensus,” Roberts said, and provides little guidance to states on what constitutes a proper assessment of intellectual disability.

The bottom line for the dissenters was that “clinicians, not judges, should determine clinical standards; and judges, not clinicians, should determine the content of the Eighth Amendment.”

A spokeswoman for the Texas attorney general’s office said the state was disappointed in the ruling but declined further comment.

In an unrelated decision issued last month that also looked at the Texas death penalty system, the Supreme Court ordered a new sentencing for an inmate who had been condemned to death on the basis of racist testimony introduced by his defense attorney. Roberts was in the majority in that case.

The issue of capital punishment deeply divides the justices. Breyer has on repeated occasions called for a case to consider whether the death penalty itself is unconstitutional.