After the setting of the initial trial date for the action, any party may obtain discovery by demanding that all parties simultaneously exchange information concerning each other's expert trial witnesses to the following extent:
§ 2034.210.Simultaneous exchange of information; time to issue
Title 4. Civil Discovery Act · Chapter 18. Simultaneous Exchange of Expert Witness Information · Article 2. Demand for Exchange of Expert Witness Information · Enacted 2004 · no amendments on record · Last verified July 29, 2026
In one sentenceSection 2034.210 lets any party, after the initial trial date is set, demand a mutual and simultaneous exchange of expert trial witness lists, requires an expert witness declaration for a retained, employed, or party-affiliated expert, and allows a further demand for simultaneous production of that expert's discoverable reports and writings.
Full Text of § 2034.210
(a) Any party may demand a mutual and simultaneous exchange by all parties of a list containing the name and address of any natural person, including one who is a party, whose oral or deposition testimony in the form of an expert opinion any party expects to offer in evidence at the trial.
(b) If any expert designated by a party under subdivision (a) is a party or an employee of a party, or has been retained by a party for the purpose of forming and expressing an opinion in anticipation of the litigation or in preparation for the trial of the action, the designation of that witness shall include or be accompanied by an expert witness declaration under Section 2034.260.
(c) Any party may also include a demand for the mutual and simultaneous production for inspection and copying of all discoverable reports and writings, if any, made by any expert described in subdivision (b) in the course of preparing that expert's opinion.
Plain-English Summary
This section opens Article 2 of the expert witness exchange chapter by giving any party, once the initial trial date has been set, a discovery tool built entirely around reciprocity. Rather than serving a one-sided demand for the other side's expert information, a party who invokes this section triggers a mutual and simultaneous exchange: every party learns who the other experts are on the same day, with nobody getting an early look at the opposing witness list before disclosing its own.
Subdivision (a) covers the basic list: names and addresses of anyone, including a party, whose expert opinion testimony a party expects to offer at trial. Subdivision (b) adds a heavier obligation for a narrower category of expert, one who is a party, a party's employee, or someone retained to form and express an opinion for the litigation. Designating that kind of expert has to include, or come with, the expert witness declaration Section 2034.260 describes, giving the other side more than just a name to work with. Subdivision (c) lets the demanding party go a step further and also require simultaneous production of that expert's discoverable reports and writings, so the underlying work behind the opinion gets turned over on the same exchange date.
Frequently Asked Questions
When can a party first demand an exchange of expert witness information under this section?
After the initial trial date for the action has been set.
What must a basic expert witness list include?
The name and address of any natural person, including a party, whose expert opinion testimony a party expects to offer at trial.
When does a designation require an expert witness declaration?
When the designated expert is a party, a party's employee, or someone retained to form and express an opinion in anticipation of litigation or trial preparation.
Can a party also demand the expert's underlying reports and writings?
Yes. Subdivision (c) lets a party demand mutual and simultaneous production of any discoverable reports and writings the retained or affiliated expert prepared.
Amendment History
(Added by Stats.2004, c. 182 (A.B.3081), § 23, operative July 1, 2005.)
Source & verification. Section text is reproduced verbatim from
the West's Annotated California Codes / Thomson Reuters. Enacted by the California Legislature.
Last verified July 29, 2026.
· Official source
Also known as: ccp 2034.210 demand exchange expert witness informationsimultaneous exchange expert witness list californiaexpert witness declaration requirement civil discovery