"In a § 1983 action, the plaintiff must also demonstrate that the defendant’s conduct was the actionable cause of the claimed injury." Harper v. City of L.A., 533 F.3d 1010, 1026 (9th Cir.2008). "To meet this causation requirement, the plaintiff must establish both causation-in-fact and proximate causation." Id. This standard of causation "closely resembles the standard ‘foreseeability’ formulation of proximate cause." Arnold v. Int’l Bus. Mach. Corp., 637 F.2d 1350, 1355 (9th Cir.1981); see also Stevenson v. Koskey, 877 F.2d 1435, 1438 (9th Cir.1989) (noting that federal courts turn to common law of torts for causation in civil rights cases).
"The inquiry into causation must be individualized and focus on the duties and responsibilities of each individual defendant whose acts or omissions are alleged to have caused a constitutional deprivation." Leer v. Murphy, 844 F.2d 628, 633 (9th Cir.1988). For example, when deprivation of a protected interest is substantively justified but the procedures were deficient, a plaintiff must show injury from the denial of procedural due process itself and cannot recover damages from the justified deprivation. Carey v. Piphus, 435 U.S. 247, 260-64 (1978); Watson v. City of San Jose, 800 F.3d 1135, 1141-42 (9th Cir.2015) (expanding types of constitutional tort actions subject to Carey’s causation analysis and quoting trial court’s damages instruction).
A person deprives another of a constitutional right, within the meaning of § 1983, "if he does an affirmative act, participates in another’s affirmative act, or omits to perform an act which he is legally required to do that causes the deprivation of which complaint is made." Preschooler II v. Clark Cnty. Sch. Bd. of Trs., 479 F.3d 1175, 1183 (9th Cir.2007) (quoting Johnson v. Duffy, 588 F.2d 740, 743 (9th Cir.1978)).
"A defendant may be held liable as a supervisor under § 1983 "if there exists either (1) his or her personal involvement in the constitutional deprivation, or (2) a sufficient causal connection between the supervisor’s wrongful conduct and the constitutional violation." Starr v. Baca, 652 F.3d 1202, 1207 (9th Cir.2011); see also Lacey v. Maricopa Cnty., 693 F.3d 896, 915-16 (9th Cir.2012) (discussing culpability and intent of supervisors). Supervisors may also be held liable under § 1983 as follows: (1) for setting in motion a series of acts by others, or knowingly refusing to terminate a series of acts by others, which they knew or reasonably should have known would cause others to inflict constitutional injury; (2) for culpable action or inaction in training, supervision, or control of subordinates; (3) for acquiescence in the constitutional deprivation by subordinates; or (4) for conduct that shows a "reckless or callous indifference to the rights of others." Starr, 652 F.3d at 1207-08; see also OSU Student Alliance v. Ray, 699 F.3d 1053, 1076 (9th Cir.2012) ("Advancing a policy that requires subordinates to commit constitutional violations is always enough for § 1983 liability … so long as the policy proximately causes the harm—that is, so long as the plaintiff's constitutional injury in fact occurs pursuant to the policy."). However, supervisors may not be held liable under § 1983 for the unconstitutional actions of their subordinates based solely on a theory of respondeat superior. Monell v. Dep’t. of Soc. Servs. of City of N.Y., 436 U.S. 658, 691 (1978); see Ashcroft v. Iqbal, 556 U.S. 662, 676 (2009).
First Amendment Retaliation Claims
When a § 1983 claim alleges discrimination because of the plaintiff’s exercise of a First Amendment right, use the "substantial or motivating factor" formulation already included in Instructions 9.11 (Particular Rights—First Amendment—Public Employees—Speech) and 9.10 (Particular Rights—First Amendment—"Citizen" Plaintiff).
"Under Monell, a plaintiff must also show that the policy at issue was the ‘actionable cause’ of the constitutional violation, which requires showing both but for and proximate causation." Tsao v. Desert Palace, Inc., 698 F.3d 1128, 1146 (9th Cir.2012) (citing Harper, 533 F.3d at 1026). Regardless of what theory the plaintiff employs to establish municipal liability— policy, custom, or failure to train— the plaintiff must establish an affirmative causal link between the municipal policy or practice and the alleged constitutional violation. See City of Canton, Ohio v. Harris, 489 U.S. 378, 385, 391-92 (1989); Van Ort v. Estate of Stanewich, 92 F.3d 831, 835 (9th Cir.1996). If the plaintiff relies on the theory of ratification, see Instruction 9.7 (Section 1983 Claim Against Local Governing Body Defendants Based on Ratification–Elements and Burden of Proof), which discusses ratification and causation.
In Oviatt v. Pearce, 954 F.2d 1470, 1481 (9th Cir.1992), the Ninth Circuit approved the trial court’s "moving force" instruction on causation in a § 1983 Monell claim as follows:
The district court instructed the jury that "in order for [the policy] to be the cause of injury, you must find that it is so closely related as to be the moving force causing the ultimate injury." Because this instruction closely tracks the language in City of Canton, we find that it correctly stated the law and adequately covered the issue of causation. See City of Canton, 489 U.S. at 391 ("the identified deficiency in a city’s training program must be closely related to the ultimate injury." (emphasis in original).
In Jones v. Williams, the Ninth Circuit affirmed a defense verdict in a § 1983 case in which the district judge gave the following "concurrent cause" instruction to address allegations of supervisory and group liability: "[M]any factors or things or the conduct of two or more persons can operate at the same time either independently or together to cause injury or damage and in such a case each may be a proximate cause." Jones v. Williams, 297 F.3d 930, 937 n.6 (9th Cir.2002).