Lat. for the "boss has to answer for what his employees do." Usually used to refer to the concept that a principal/employer has responsibility for the actions/omissions of agents/employees
The key issue under California law is whether the act was committed in the course of carrying out the employer's business. Perez v. Van Groningen & Sons, Inc., 41 Cal.3d 962, 719 P.2d 676, 227 Cal. Rptr. 106 (1986).
When it comes to the control of people, the background rule is that "a person owes no duty to control the conduct of another." Beauchene, 88 Cal. App. 3d at 347, 151 Cal. Rptr. at 798. California courts have carved out an exception to that rule, "where a special relationship exists between the defendant and the injured party, or between the defendant and the active wrongdoer." Id. (citing Tarasoff v. Regents of Univ. of Cal., 17 Cal. 3d 425, 435, 131 Cal. Rptr. 14, 23, 551 P.2d 334 (1976)).