The law known as Action for Neglect to Prevent (42 U.S.C. § 1986) focuses on holding individuals accountable for failing to stop civil rights violations they knew were about to happen. If someone has knowledge of a planned act that would deprive another person of their civil rights, and has the power to prevent it, but neglects to do so, they can be liable for any damages caused by the wrongful act. This applies even if the individual wasn't directly involved in the violation itself. The law serves as a way to encourage bystanders to intervene and prevent harm when they can.
42 U.S.C. § 1986
Every person who, having knowledge that any of the wrongs conspired to be done, and mentioned in section 1985 of this title, are about to be committed, and having power to prevent or aid in preventing the commission of the same, neglects or refuses so to do, if such wrongful act be committed, shall be liable to the party injured, or his legal representatives, for all damages caused by such wrongful act, which such person by reasonable diligence could have prevented; and such damages may be recovered in an action on the case; and any number of persons guilty of such wrongful neglect or refusal may be joined as defendants in the action; and if the death of any party be caused by any such wrongful act and neglect, the legal representatives of the deceased shall have such action therefor, and may recover not exceeding $5,000 damages therein, for the benefit of the widow of the deceased, if there be one, and if there be no widow, then for the benefit of the next of kin of the deceased. But no action under the provisions of this section shall be sustained which is not commenced within one year after the cause of action has accrued. (R.S. § 1981.)