The Supreme Court avoided issuing a final decision on one of the most sensitive debates within the American judicial system: the application of the death penalty to people with intellectual disabilities.

In an unusual ruling without detailed explanation, the highest court dismissed the state of Alabama's appeal to execute Joseph Clifton Smith, a 55-year-old man convicted of murder in 1997 and who has spent nearly three decades on death row.

The resolution leaves in place the ruling of lower courts that concluded that Smith has an intellectual disability and, therefore, is protected from capital punishment under the United States Constitution.

The decision divided the justices. Liberal justices Sonia Sotomayor and Ketanji Brown Jackson supported dismissal of the case, along with conservatives Brett Kavanaugh and Amy Coney Barrett.

In contrast, conservative justices Samuel Alito, Clarence Thomas, John Roberts and Neil Gorsuch criticized the decision and considered that the Supreme Court missed a key opportunity to clarify how these borderline cases should be evaluated.

Debate on IQ and capital punishment

The focus of the case revolved around how courts should interpret multiple IQ tests on people sentenced to death.

The five IQ evaluations performed on Smith produced results between 72 and 78, figures slightly higher than the threshold of 70 that has historically served as a reference for determining intellectual disability in capital punishment proceedings.

However, lower courts took into account other factors beyond the numerical evidence. Among them, Smith's school history, who was placed in special education classes, dropped out of school in seventh grade and had severe learning and social adaptation difficulties.

According to court documents, his math skills were at the level of a kindergartener, while his reading and writing abilities were equivalent to those of elementary school students.

A federal court further found that Smith had significant problems performing everyday tasks, including managing money, maintaining a bank account or buying groceries without assistance.

The Supreme Court avoids setting a national standard

Although the Supreme Court had agreed to review the case months ago, it ultimately chose to dismiss it for procedural reasons, thus avoiding establishing a national standard on how to analyze IQ results in death row inmates.

In a concurring opinion, Sotomayor argued that methods for evaluating intellectual disability are complex even among specialists and that the Supreme Court was not in a position to establish clear guidance for all courts in the country.

“The court is not qualified to provide meaningful guidance on how multiple IQ scores should be evaluated,” the justice wrote.

The decision preserves a historical precedent issued in 2002, when the Supreme Court prohibited executing people with intellectual disabilities on the grounds that it violates the Eighth Amendment of the Constitution, which prohibits cruel and unusual punishment.

However, the original ruling left it up to the states to define specific criteria, which has generated important differences between jurisdictions and constant judicial disputes.

Smith's case could have national repercussions because dozens of death row inmates in different states present similar profiles, with IQ results located on the borderline between intellectual disability and eligibility for the death penalty.

Currently, the United States and Japan are the only G7 nations that still maintain the death penalty in force.