Is a prison officer obligated to take steps to prevent an assault on an inmate?

The prison official need not "believe to a moral certainty that one inmate intends to attack another at a given place at a time certain before [he] is obligated to take steps to prevent such an assault." Berg v. Kincheloe, 794 F.2d 457, 459 (9th Cir.1986). However, before being required to take

Page 10

action the prison official must have more than a "mere suspicion" that an attack will occur. See id. To prove knowledge of the risk a plaintiff may rely on circumstantial evidence. The obviousness of the risk may be sufficient to establish knowledge. See Farmer, 511 U.S. at 842; Wallis v. Baldwin, 70 F.3d 1074, 1077 (9th Cir.1995). Thus, "a factfinder may conclude that a prison official knew of a substantial risk from the very fact that the risk was obvious." Farmer, 511 U.S. at 842.