What is the test for determining whether a prison can be held liable for failing to protect an inmate from harm?

know for a certainty that the inmate's safety is in danger, but it requires proof of more than a mere suspicion of danger. See Berg v. Kincheloe, 794 F.2d 457, 459 (9th Cir. 1986). Finally, the plaintiff must show that prison officials disregarded a risk. Thus, where prison officials actually knew of a substantial risk, they are not liable if they took reasonable steps to respond to the risk, even if harm ultimately was not averted. See Farmer, 511 U.S. at 844.