California Code, Penal Code - PEN § 1138

After the jury have retired for deliberation, if there be any disagreement between them as to the testimony, or if they desire to be informed on any point of law arising in the case, they must require the officer to conduct them into court. Upon being brought into court, the information required must be given in the presence of, or after notice to, the prosecuting attorney, and the defendant or his counsel, or after they have been called.