Marvin Wilson, a 54-year-old inmate whose attorneys insist his low IQ should have disqualified him from the death penalty, was executed last night. He was the seventh man to be taken to Texas’s death chamber this year.

Despite his lawyers’ petition that Wilson’s execution be stayed due to his mental capacity, the U.S. Supreme Court denied his appeal less than two hours before his 6 p.m. lethal injection.

Wilson’s case, in particular, caught the national media’s attention because of the extremely low IQ score—61—that Wilson earned on a 2004 test. The “minimum competency standard” is generally around a seventy IQ, which puts Wilson below the first percentile of intelligence and means he met the “standard clinical definition of mental retardation,” Paul Campos, a law professor at the University of Colorado at Boulder, wrote at Salon. Wilson also sucked his thumb as an adult, didn’t know how to use a phone book or a ladder, and had trouble performing elementary tasks without aid. And the state of Texas never disputed Wilson’s low intelligence.

Wilson was a victim of the “savage arbitrariness of the death penalty as it is employed by the state of Texas. Poor, black, with the mental age of a six-year-old, he was sentenced to death for his ambiguous role in a drug-trade murder, when literally every day in America people are given far lighter sentences for more heinous crimes,” Campos opined.

But did his execution fly in the face of a 2002 Supreme Court decision that barred executing the mentally retarded? At the Nation, Liliana Segura said yes, dubbing Wilson’s case “a flagrant violation of the 2002 Supreme Court ruling in Atkins v. Virginia, which held that ‘the mentally retarded should be categorically excluded from execution,’ period.” Campos agreed with this sentiment.

But Atkins v. Virginia leaves it up to individual states to decide just how mentally inept a person who is excused from lethal injection should be. To do this, Texas does not rely on a statute, but instead lets courts use Briseño factors, which Human Rights Watch summarized this way in a press release denouncing Wilson’s impending execution:

The “Briseño factors,” named for the Texas court decision detailing them, consist of seven “evidentiary factors” that Texas finds to be indicative of intellectual disability. These factors include whether the defendant can formulate and carry out plans, display leadership, effectively lie or hide facts to protect the person’s self-interest, and respond appropriately and coherently. Texas appears to allow for execution if just one Briseño factor is met.

When developing the Briseño factors, the Texas Court of Criminal Appeals dragged Steinbeck’s classic, Of Mice and Men, into the mix, writing of Lennie Small, a mentally retarded character:

Most Texas citizens would agree that Steinbeck’s Lennie should, by virtue of his lack of reasoning ability and adaptive skills, be exempt from execution. But does a consensus of Texas citizens agree that all persons who might legitimately qualify for assistance under the social services definition of mental retardation be exempt from an otherwise constitutional penalty?

The Texas Tribune‘s Brandi Grissom tracked down Steinbeck’s son, Thomas, who said his late father would be “deeply angry and ashamed” that his work was being used in this way.

“His work was certainly not meant to be scientific, and the character of Lennie was never intended to be used to diagnose a medical condition like intellectual disability,” Thomas Steinbeck said. “I find the whole premise to be insulting, outrageous, ridiculous and profoundly tragic:”

Wilson was on death row for the 1992 murder of 21-year-old Jerry Williams, a drug informant who had tipped off police about Wilson possessing cocaine. Michael Graczyk of the Associated Press had the details of the murder: