What is the legal test for deliberate indifference in prison?

Deliberate indifference is shown where the official is aware of a serious medical need and fails to adequately respond. Simmons v. Navajo County, Ariz., 609 F.3d 1011, 1018 (9th Cir. 2010). "Deliberate indifference is a high legal standard." Simmons, 609 F.3d at 1019; Toguchi v. Chung, 391 F.3d 1051, 1060 (9th Cir. 2004). The prison official must be aware of facts from which he could make an inference that "a substantial risk of serious harm exists" and he must make the inference. Farmer, 511 U.S. 825, 837, 114 S.Ct. 1970, 1979 (1994).