California Rules Regarding Expert Witness Depositions and Interrogatories 

As described in the following section, both parties to a case must disclose the identity of and other information regarding the expert witnesses they expect to call at trial upon demand by either party. Under Section 2034.410 of the California Code of Civil Procedure, any expert disclosed pursuant to that requirement may be deposed by the opposing party. Absent exceptional hardship, Section 2034.420 requires the deposition to take place within 75 miles of the courthouse where the case is pending. While depositions in California are generally limited to seven hours, Section 2025.290(b)(2) expressly provides that this time limit does not apply in expert witness depositions. However, an expert could receive a protective order from a court limiting the time of a deposition if the expert is subject to unwarranted annoyance, embarrassment, oppression, or undue burden.

Expert witnesses cannot be subject to interrogatories in California. Under Section 2030 of the California Code of Civil Procedure and cases interpreting that provision, interrogatories must be directed at the opposing party, not its witnesses. See Mowry v. Superior Court of El Dorado County, 20 Cal. Rptr. 698, 701 (Cal. Ct. App. 1962). 

California Expert Witness Reports and Disclosures Rules 

Under Section 2034.210 of the California Code of Civil Procedure, the parties to a case must simultaneously disclose information regarding the expert witnesses they expect to call at trial upon demand by either party. This mutual disclosure must include a list identifying the name and address of the experts and, if included in the demand for disclosure, all discoverable reports and writings by the experts. 

Rules Regarding Lawyer-Expert Communications, Draft Expert Witness Reports, Expert Witness Notes, Etc. in California 

California courts have interpreted the scope of “discoverable” reports broadly, finding it to include even partially prepared drafts. See Beck v. Hirchag, 2011 Cal. App. Unpub. LEXIS 2649, at *16 (Cal. Ct. App. Apr. 11, 2011). However, experts are not required to prepare reports, and California practice guides even suggest counsel to encourage their experts not to prepare reports so as to protect against discovery. Id. at 15 (citing Weil & Brown, Cal. Practice Guide: Civil Procedure Before Trial (The Rutter Group 2010) p. 8J-17). Attorneys and experts must be cautious in utilizing such a strategy, though, so as not to appear to have “intentionally manipulated the discovery process to ensure that expert reports and writings were not created until after the specified date.” Boston v. Penny Lane Centers, Inc., 88 Cal. Rptr. 3d 707, 721 (Cal. Ct. App. 2009). Such a finding would result in exclusion of the expert’s opinions.