28 CFR 541.27 - Protection case
You may be placed in administrative detention status as a protection case in the following circumstances.
(a) Victim of inmate assault or threats. You were the victim of an inmate assault, or are being threatened by other inmates, including threats of harm if you do not act in a certain way, for example, threats of harm unless you engage in sexual activity.
(b) Inmate informant. Your safety is threatened because you provided, or are perceived as having provided, information to staff or law enforcement authorities regarding other inmates or persons in the community.
(c) Inmate refusal to enter general population. You refuse to enter the general population because of alleged pressures or threats from unidentified inmates, or for no expressed reason.