What is the test for finding a prison official liable under the Eighth Amendment for failing to protect an inmate from harm?

Rhodes v. Robinson, 408 F.3d 559, 567-68 (9th Cir. 2005) (footnote and citations omitted). Plaintiff cannot simply state that defendants conduct was retaliatory, he must allege enough facts to show that each defendant's action was taken because of his protected conduct.

To state a due process claim, plaintiff must show that the condition complained of imposed an "atypical and significant hardship on [him] in relation to the ordinary incidents of prison life." Sandin v. Conner, 515 U.S. 472, 484 (1995) (internal citations omitted).

Finally, "a prison official violates the Eighth Amendment only when two requirements are met. First, the deprivation alleged must be, objectively, sufficiently serious; a prison official's act or omission must result in the denial of the minimal civilized measure of life's necessities." Farmer v. Brennan, 511 U.S. 825, 834 (1994) (internal quotation marks and citations omitted). Second, the prison official must subjectively have a sufficiently culpable state of mind, "one of deliberate indifference to inmate health or safety." Id. (internal quotation marks and citations omitted). The official is not liable under the Eighth Amendment unless he "knows of and disregards an excessive risk to inmate health or safety." Id. at 837. Then he must fail to take reasonable measures to lessen the substantial risk of serious harm. Id. at 847. Negligent failure to protect an inmate from harm is not actionable under 1983. Id. at 835.