What is the test for providing additional explanations to a jury in a personal injury action?

Initially, we note that defendant has forfeited any claim of error, as he agreed to action taken by the trial court. (See People v. Rogers (2009) 46 Cal.4th 1136, 1162, fn. 14.) And, in any event, the claim fails on its merits. Under section 1138, "[t]he court has a primary duty to help the jury understand the legal principles it is asked to apply. [Citation.] This does not mean the court must always elaborate on the standard instructions. Where the original instructions are themselves full and complete, the court has discretion under section 1138 to determine what additional explanations are sufficient to satisfy the jury's request for information. [Citation.]" (People v. Beardslee (1991) 53 Cal.3d 68, 97.)