What is the test for a tortfeasor to claim cruel and unusual punishment under the Eighth Amendment?

To prevail on a claim of cruel and unusual punishment a prisoner must allege and prove that objectively he suffered a sufficiently serious deprivation and that subjectively prison officials acted with deliberate indifference in allowing or causing the deprivation to occur. Wilson v. Seiter, 501 U.S. 294, 298-99 (1991). The deliberate indifference standard involves an objective and subjective prong. First, the alleged deprivation must be, in objective terms, "sufficiently serious. . . ." Farmer, 511 U.S. at 834 (citing Wilson v. Seiter, 501 U.S. at 298). Second, the prison official must "know[ ] of and disregard[ ] an excessive risk to inmate health or safety. . . ." Farmer, 511 U.S. at 837. Thus, a prison official may be held liable under the Eighth Amendment for denying humane conditions of confinement only if he knows that inmates face a substantial risk of harm and disregards that risk by failing to take reasonable measures to abate it. Id. at 837-45.