What is the test for a municipality to be liable under Section 1983 of the Civil Code for failing to discipline or discipline a subordinate who committed an unconstitutional act?

subordinate's actions in order for the municipality to be liable. Sheehan, 743 F.3d at 1231. "The policymaker must have knowledge of the constitutional violation and actually approve of it," and a "mere failure to overrule a subordinate's actions, without more, is insufficient to support a 1983 claim." Lytle v. Carl, 382 F.3d 978, 987 (9th Cir. 2004). Similarly, the "mere failure to discipline [a subordinate] does not amount to ratification of [the subordinate's] allegedly unconstitutional actions." Sheehan, 743 F.3d at 1231.