Municipal liability under §1983 must be based on enforcement of a municipal policy or practice. The policy may be a formally adopted policy such as an ordinance or regulation, a custom or practice that is so persistent and well settled as to have the force of law, or the final decision of an official who has policymaking authority. Monell v. NYC Dep't of Social Services, 436 U.S. 658, 690 (1978). This column focuses on municipal customs and practices.

The U.S. Court of Appeals for the Second Circuit's recent decision in Lucente v. County of Suffolk, 980 F.3d 284 (2d Cir. 2020) provides important guidance on the relevance and sufficiency of evidence to prove a municipal custom or practice. Lucente builds upon the circuit's earlier decisions on these issues. See Cash v. County of Erie, 654 F.3d 324 (2d Cir. 2011); Matusick v. Erie Cnty. Water Auth., 757 F.3d 31 (2d Cir. 2014); Sorlucco v. New York City Police Dep't, 971 F. 2d 864 (2d Cir. 1989).