Private employers are generally responsible for the actions of their employees. That’s because private employers have a degree of control over their employees through hiring, firing, discipline, and setting employment policies. Although government employers have the same degree of control over their employees, they are generally immune from liability when their employees hurt people by violating the Constitution.
In addition to sovereign immunity—which under the un-American concept of “the King can do no wrong” prevents Americans from suing the federal or state government directly unless the government consents to be sued—the Supreme Court has created another doctrine to protect cities, counties, and other lower-level government employers. Through a 1978 decision called Monell, the Court held that government employers that are not entitled to sovereign immunity are still immune from liability for the actions of their employees unless a victim can show that those actions flow directly from an official policy or custom of the employer.
Thanks to Monell, short of a government employer formally instructing its employees to violate the Constitution, it is very difficult to hold a government employer accountable. And to make things worse, courts have recently begun using qualified immunity to further erode what little constitutional accountability exists for government employers.