What is the test for establishing causation in a civil rights case?

Causation is a concept that is not often discussed or explicitly stated in civil rights cases. When courts examine the elements of civil rights causes of action, they tend to focus on the substantive aspects of liability under the statutes. See, e. g., Sykes v. California, 497 F.2d 197, 200 (9th Cir. 1974). Although causation is not stated explicitly in these formulations, it is an implicit requirement. A section 1985 cause of action requires the plaintiff to show "that the acts done in furtherance of the conspiracy resulted " in his injury. Id. (emphasis added). ¹ This is the equivalent of saying that the plaintiff must show that the defendants caused his injury. In a section 1983 cause of action the plaintiff must show that the defendants have deprived him of a right. Id. The language of the statute shows this can be a direct or indirect deprivation. It creates liability for any person who "subjects, or causes to be subjected" particular persons to the deprivation of particular rights. Thus, liability under section 1983 can be established by showing that the defendant personally participated in a deprivation of the plaintiff's rights, or caused such a deprivation to occur.