California Code, Labor Code - LAB § 3855

If the employee joins in or prosecutes such action, either the evidence of the amount of disability indemnity or death benefit paid or to be paid by the employer or the evidence of loss of earning capacity by the employee shall be admissible, but not both.  Proof of all other items of damage to either the employer or employee proximately resulting from such injury or death is admissible and is part of the damages.