A vital difference between constitutional litigation under 42 U.S.C. §1983 and common law tort litigation is that there is no respondeat superior liability under §1983. This means that a municipality sued under §1983 may not be held liable solely because it employed a constitutional wrongdoer. Rather, the plaintiff must demonstrate that the violation of her constitutional rights was attributable to the enforcement of a municipal policy or practice. This is the familiar Monell rule (Monell v. Department of Social Services, 436 U.S. 658 (1978)), and it is typically quite difficult for §1983 plaintiffs to satisfy.
Consider, for example, a §1983 claim that the arresting officer employed excessive force and, as is common, the plaintiff sues both the officer and the municipality. To establish municipal liability the plaintiff will have to show that the use of excessive force was closely linked to the enforcement of a municipal policy or practice. Since a municipality would not adopt a formal policy authorizing their police officers to employ excessive force, the plaintiff will have to establish some type of municipal custom or practice, such as systemic excessive force inflicted by the municipality’s police officers, or perhaps a custom or practice of deliberately indifferent training or supervision by municipal policymakers. Inadequate training and supervision claims must meet stringent fault and causation standards, normally requiring the plaintiff to prove a pattern of similar constitutional violations. See, e.g., Connick v. Thompson, 131 S. Ct. 1350 (2011); City of Canton v. Harris, 489 U.S. 378 (1989).
