Supreme Court justices generally support their opinions with references to other cases and perhaps the occasional scientific study. But on Thursday, Justice Clarence Thomas cited an unusual source in his dissent in a death penalty case: the memoir of a professional football player. The player is also the son of the victim in the case. Thomas' unorthodox move prompted two of his fellow conservatives to distance themselves from this section of his dissent, which they otherwise supported.

The case in question is Brumfield v. Cain, in which death row inmate Kevan Brumfield argued that the state of Louisiana denied him the opportunity to prove in court that he is intellectually disabled and, consequently, exempt from execution. Brumfield's attorney had presented evidence that Brumfield was born prematurely, had been in special ed in elementary school, had a low IQ of 75, had been abused by his stepfather, and had spent time in a mental hospital and group homes due to his disability. But he was sentenced to death before a 2002 Supreme Court decision that the Eighth Amendment barred the execution of the intellectually disabled. After that decision, Brumfield petitioned the Louisiana courts to allow him a hearing to show that his disability should exempt him from execution. The Louisiana courts denied his requests, and the federal Fifth Circuit Court of Appeals upheld that decision. On Thursday, the Supreme Court majority reversed the lower court and ruled in Brumfield's favor, sending his case back to Louisiana for further hearings on his mental capacity.

Thomas wrote a lengthy dissent in the case, contending that the court should defer to Louisiana and let the execution proceed. But he also suggested Brumfield should stop blaming his horrible childhood for his crimes because, after all, not everyone with a horrible childhood becomes a murderer.

Thomas' case in point: Warrick Dunn, the author of the 2008 memoir Running for My Life: My Journey in the Game of Football and Beyond. Dunn, formerly a star NFL running back, is a minority owner of the Atlanta Falcons. Brumfield murdered Dunn's mother when Dunn was 18. Here's how Thomas sets up the case: