In order to establish that the [act[s]] [failure to act] of the defendant [specify name of individual defendant, supervisor’s subordinates, local governing body, or local body’s official, police officer, employee, or final policymaker] deprived the plaintiff of [his] [her] particular rights under [the laws of the United States] [the United States Constitution] as explained in later instructions, the plaintiff must prove by a preponderance of the evidence that the [[act[s]] [failure to act]] [was] [were] so closely related to the deprivation of the plaintiff’s rights as to be the moving force that caused the ultimate injury.
When a Section 1983 claim alleges discrimination because of the plaintiff’s exercise of a First Amendment right, do not use this instruction because the "substantial or motivating factor" formulation is already included in Instructions 9.9 (Particular Rights—First Amendment—Public Employees—Speech) and 9.10 (Particular Rights—First Amendment—"Citizen" Plaintiff). See also Lakeside-Scott v. Multnomah County, 556 F.3d 797 (9th Cir. 2009); DiRuzza v. County of Tehama, 206 F.3d 1304 (9th Cir. 2000).
In Oviatt v. Pearce, 954 F.2d 1470, 1481 (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.7 (9th Cir.2002).