In a moment, I'll quote the abuse allegation, but first let's focus on the Thomas/Scalia opinion. They agree with the rest of the Court that the 4th Circuit approach in Wilkins is inconsistent with Hudson, and thus should be reversed under existing precedent. However, Justice Thomas says (as he did in 1992) that Hudson itself was wrongly decided. According to Justice Thomas's reading of the historical record, the original understanding of the 8th Amendment applied only to "punishments" that were carried out as part of a prisoner's sentence. A guard inflicting unauthorized cruelty on a prisoner is not, in this view, "punishing" the prisoner, even if he is harming the prisoner.
Justice Thomas did not say in Hudson that the original understanding should prevail. Rather, he said then, and he reiterated yesterday, that in order to prevent the 8th Amendment from becoming "a National Code of Prison Regulation," 8th Amendment claims for abuse that is not part of the sentence should be limited to those that result in "serious injury." It's not entirely clear why even those claims should be allowed under the Thomas approach. Purporting to root the serious-injury requirement in an earlier ruling, Justice Thomas could be said to have relied on stare decisis--although if that's the reason, one wonders why Hudson itself is not now entitled to respect under stare decisis, and in any event, Justice Thomas frequently advocates abandoning precedent in the name of original understanding.
Perhaps the best explanation why Justice Thomas is willing to allow 8th Amendment claims for even the narrow category of unauthorized abuse that results in serious injury is that he is, at the end of the day, a "faint-hearted originalist." That's Justice Scalia's term. He says in a 1989 essay titled "Originalism: The Lesser Evil," that most originalists (presumably including himself) are "faint-hearted," i.e., they would, in extremis, discard the original understanding to avoid truly dreadful results. Interestingly, he gives "public flogging" as an example: Practiced in the 18th century, he says that even most originalists would likely find it violates the 8th Amendment today.
Accordingly, we might view the willingness of Justices Thomas and Scalia to go along with precedents establishing that the 8th Amendment bars unauthorized prisoner abuse by guards where serious injury results as a sign of their faint-heartedness, i.e., as a sign that each has some compassion for prisoners after all. But before you conclude that this makes Justices Thomas and Scalia all warm and fuzzy, take note of how UN-fainthearted they are. If they had their druthers, they would do away with Hudson and would thus deny that an 8th Amendment violation has occurred when "serious injury" has not occurred.
What, in particular, would they say does NOT violate the 8th Amendment? Here is the allegation of abuse from the plaintiff's complaint in yesterday's case, quoted by the majority: Gaddy, the defendant guard,
apparently angered by Wilkins’ request for a grievance form, “snatched [Wilkins] off the ground and slammed him onto the concrete floor.” Gaddy “then proceeded to punch, kick, knee and choke [Wilkins] until another officer had to physically remove him from [Wilkins].” Wilkins further alleged that, “[a]s a result of the excessive force used by [Gaddy], [he] sustained multiple physical injuries including a bruised heel, lower back pain, increased blood pressure, as well as migraine headaches and dizziness” and “psychological trauma and mental anguish including depression, panic attacks and nightmares of the assault.”
Because the district judge characterized all of this as "de minimis," it did not satisfy the "serious injury" requirement that Justices Thomas and Scalia would impose on 8th Amendment claims that do not challenge the formal sentence. I guess they're not so faint-hearted after all.