California Code, Penal Code - PEN § 31

All persons concerned in the commission of a crime, whether it be felony or misdemeanor, and whether they directly commit the act constituting the offense, or aid and abet in its commission, or, not being present, have advised and encouraged its commission, and all persons counseling, advising, or encouraging children under the age of fourteen years, or persons who are mentally incapacitated, to commit any crime, or who, by fraud, contrivance, or force, occasion the drunkenness of another for the purpose of causing him to commit any crime, or who, by threats, menaces, command, or coercion, compel another to commit any crime, are principals in any crime so committed.