What is the test for determining whether a prison official was responsible for injuries sustained to an inmate?

Second, the inmate must satisfy the subjective element; the prison official must have acted with deliberate indifference. Farmer, 511 U.S. at 834. This means that the prison official must "know of and disregard an excessive risk to inmate health or safety; the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Id. at 837. "Mere negligence is not sufficient to establish liability." Frost v. Agnos, 152 F.3d 1124, 1128 (9th Cir. 1998). Prison officials may avoid liability by: (1) proving they were unaware of the risk, or (2) proving they "responded reasonably to the risk, even if the harm ultimately was not averted." Farmer, 511 U.S. at 844-45.

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