For the second time in his case, the U.S. Supreme Court reversed an inmate's death penalty sentence because of his intellectual disability.

The court's 6-3 decision Feb. 19 did not return the case to the lower courts as it did two years ago but instead tossed out the lower court's decision to execute Bobby James Moore, saying the inmate's mental disability prevents him from being put to death.

Sister Helen Prejean, a Sister of St. Joseph of Medaille, and a longtime opponent of the death penalty, explained the court's decision in a few tweets Feb. 19 where she said: "Texas courts failed to properly consider clear evidence of intellectual disability," and that the Supreme Court's opinion was "particularly notable" because it is "a flat-out ruling that Bobby James Moore cannot be executed."

In its 2017 ruling in Moore's case, the Supreme Court said the state of Texas was using outdated standards to determine a person's intellectual disability, particularly in determining capital punishment. The court sent the case back to the Texas Court of Criminal Appeals, but that court refused to change its original ruling, thus bringing Moore's case back to the nation's high court.

Moore, 59, was sentenced to death nearly 40 years ago after being convicted of killing a clerk during a grocery-store robbery in April 1980. In 2014, a Texas court determined under current medical standards that Moore was intellectually disabled due to his low IQ scores and his inability to tell time or days of the week.

The Supreme Court's latest ruling on Moore, opposed by Justices Samuel Alito, Clarence Thomas and Neil Gorsuch, was yet another look at how states decide who has mental disabilities and is ineligible for the death penalty. In the court's 2002 ruling in Atkins v. Virginia, it said executing people with intellectual disabilities violates the Eighth Amendment's ban on cruel and unusual punishment, but it left it up to the states to implement this decision.

In Moore's case, lawyers have argued that he is intellectually disabled. But the Texas Court of Criminal Appeals has ruled twice that he is not, even after promising to use more modern standards the second time it reviewed his case.

The Supreme Court did not concur, saying the majority agrees "with Moore and the prosecutor that, on the basis of the trial court record, Moore has shown he is a person with intellectual disability."

The court's opinion also said it found the lower court repeated the same analysis "we previously found wanting, and these same parts are critical to its ultimate conclusion."

Amy Howe, writing for a blog about the Supreme Court, scotusblog, said in 2017 that the court's decision in Moore was a not just a victory for him but for other intellectually disabled inmates on death row in Texas.

"It will likely lead to new litigation in the other states that have not adopted legal definitions of intellectual disability that are not specifically based on the current medical standards," she added.