Cal. Health & Safety Code § 25395.84
(a) A court of competent jurisdiction may award reasonable attorneys’ fees and experts’ fees to a person who initiates a claim under an applicable law for contribution for, or recovery of, response costs incurred for a response action, or for any other response costs incurred at a site, if the person meets all of the following criteria:
(3) On or before 20 calendar days prior to the date of the trial on issues relating to the response costs at issue, the person serves on the defendant both of the following: