Cal. Civ. Proc. Code § 608

In charging the jury the Court may state to them all matters of law which it thinks necessary for their information in giving their verdict; and, if it state the testimony of the case, it must inform the jury that they are the exclusive judges of all questions of fact. The Court must furnish to either party, at the time, upon request, a statement in writing of the points of law contained in the charge, or sign, at the time, a statement of such points prepared and submitted by the counsel of either party.