WASHINGTON — In 2002, the Supreme Court barred the execution of the intellectually disabled. But it gave states a lot of leeway to decide just who was, in the language of the day, “mentally retarded.”

Texas took a creative approach, adopting what one judge there later called “the Lennie standard.” That sounds like a reference to an august precedent, but it is not. The Lennie in question is Lennie Small, the dim, hulking farmhand in John Steinbeck’s “Of Mice and Men.”

The Lennie in question is fictional.

Still, Judge Cathy Cochran of the Texas Court of Criminal Appeals wrote in 2004 that Lennie should be a legal touchstone.

“Most Texas citizens might agree that Steinbeck’s Lennie should, by virtue of his lack of reasoning ability and adaptive skills, be exempt” from the death penalty, she wrote. “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?”