What is the test for finding a municipality liable for failing to act in a civil case?

To find a municipality liable for a failure to act, the plaintiff must show that an employee of the municipality violated his constitutional rights, that the customs or policies of the municipality amount to deliberate indifference, and those "customs or policies were the moving force behind" the violation of plaintiff's constitutional rights. Long v. County of Los Angeles, 442 F.3d 1178, 1186 (9th Cir. 2006). For a custom or policy to be the moving force behind the constitutional violation, it must be "closely related to the ultimate injury." Long, 442 F.3d at 1190.