What is the current state of the law on the duty of a prison officer to protect a prisoner from violence at the hands of other inmates?

Under the Eighth Amendment, "prison officials have a duty to protect prisoners from violence at the hands of other prisoners." Farmer v. Brennan, 511 U.S. 825, 833 (1994) (internal quotation marks, ellipsis, and citation omitted). The relevant inquiry is whether prison officials, "acting with deliberate indifference, exposed a prisoner to a sufficiently substantial risk of serious damage to his future health." Id. at 834 (internal quotation omitted). A defendant is deliberately indifferent if he knows that the plaintiff faces "a substantial risk of serious harm and disregards that risk by failing to take reasonable measures to abate it." Id. at 847. Plaintiff has not shown how any particular defendant was deliberately indifferent to a substantial risk of serious harm to him.