What constitutes deliberate indifference under the Eighth Amendment?

"Deliberate indifference occurs when '[an] official acted or failed to act despite his knowledge of a substantial risk of serious harm.' " Solis v. Cnty. of Los Angeles, 514 F.3d 946, 957 (9th Cir. 2008). A prisoner may state "a cause of action under the Eighth Amendment by alleging that [prison officials] have, with deliberate indifference, exposed him to [environmental conditions] that pose an unreasonable risk of serious damage to his future health." Helling v. McKinney, 509 U.S. 25, 35 (1993).

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