California Code of Civil Procedure section 2034.210 is the statute that lets any party in a California civil case, once the court has set the initial trial date, serve a written demand requiring every side to simultaneously disclose the expert witnesses they intend to call at trial. The demand can cover three things: a list of each expert’s name and address, a sworn declaration about certain experts’ expected testimony and fees, and, if the demand says so, production of the discoverable reports and writings those experts prepared.1California Legislative Information. California Code of Civil Procedure 2034.210 Mishandle the deadlines or leave pieces out, and the court can bar your expert from testifying.
When the Demand Must Be Served
The window is short, and it opens the moment the court sets the initial trial date. A party can serve the demand without leave of court, but service must happen no later than the 10th day after the trial date is set, or 70 days before that trial date, whichever is closer to trial.2California Legislative Information. California Code of Civil Procedure 2034.220 In a case set on a short fuse, that can mean as few as 10 days to get the demand out.
Serve it on every party who has appeared in the case.3California Legislative Information. California Code of Civil Procedure 2034.240 The demand itself is not filed with the court.
What the Demand Must Say
The demand is a written document under section 2034.230. Below the case caption, it must identify the party making it and state that it is made under Chapter 18 of the Code of Civil Procedure. It must set a specific date for the exchange, calculated as either 50 days before the initial trial date or 20 days after service of the demand, whichever is closer to trial.4California Legislative Information. California Code CCP 2034.230 The court can adjust that date for good cause; otherwise the calculated date controls. The demand should also state whether it calls for just the list and declarations or also the production of expert reports and writings, and it should specify the place of exchange.
What Gets Exchanged, and How
On the date set by the demand, every party hands over their disclosures at the same time. The exchange has three possible components:
- A list of every expert the party expects to offer at trial, with the expert’s name and address. This covers any witness whose testimony will be in the form of expert opinion, including a party, an employee of a party, or an outside professional.
- A signed declaration about certain experts (see below).
- If the demand asked for them, all discoverable reports and writings prepared by designated retained experts in forming their opinions. Those must be produced at the same time as the lists.5California Legislative Information. California Code of Civil Procedure 2034.270
Simultaneity is the point. Neither side sees the other’s lineup before committing to its own, which keeps a party from reverse-engineering their experts around the opposition’s choices.
The Expert Witness Declaration
A declaration under section 2034.260 must accompany the exchange for any expert who is a party, an employee of a party, or a person retained by a party for the purpose of forming and expressing an opinion in the case. The declaration is signed by the designating party’s attorney, or by the party directly if self-represented, under penalty of perjury, and must contain all five of the following:6California Legislative Information. California Code of Civil Procedure 2034.260
- A brief description of the expert’s qualifications.
- A summary of the general substance of the testimony the expert is expected to give.
- A representation that the expert has agreed to testify at trial.
- A representation that the expert will be sufficiently familiar with the pending action to submit to a meaningful deposition on the specific opinions planned.
- The expert’s hourly and daily fees for providing deposition testimony and for consulting with the retaining attorney.
That last item trips people up. The declaration must disclose the consulting rate as well as the deposition rate; listing only one makes the declaration deficient.
Adding a Rebuttal Expert After the Exchange
Section 2034.280 gives each party 20 days after the exchange to serve a supplemental list naming an expert on a subject the party had not previously covered, in response to an opponent’s designation on that subject. The supplemental list is available only if the party has not already retained an expert on that subject.7California Legislative Information. California Code of Civil Procedure CCP 2034.280 The supplemental designation requires the same declaration and discoverable writings as the original exchange, and the newly added expert must be made available for deposition immediately, even if the normal discovery cutoff has passed.
What Happens If You Don’t Comply
Under section 2034.300, on objection from any party who did comply, the court shall exclude the expert testimony of a party who unreasonably failed to:8California Legislative Information. California Code of Civil Procedure 2034.300
- List the witness as an expert in the exchange;
- Submit the required expert witness declaration;
- Produce discoverable reports and writings; or
- Make the expert available for deposition.
The “shall” is mandatory. Once a compliant party objects, the court lacks discretion to overlook the failure. In cases that rise or fall on expert opinion, such as a personal-injury claim that needs medical testimony on causation, exclusion of the expert can effectively end the claim or defense.
If You Missed the Deadline or Need to Add an Expert Later
Section 2034.610 provides a narrow route back in. A party who participated in a timely exchange can move the court for leave to augment the expert list or amend the expected substance of an existing expert’s testimony.9California Legislative Information. California Code of Civil Procedure 2034.610 The motion must be made early enough that the opposing party can still depose the new or amended expert before the discovery cutoff, unless the court permits a later motion under exceptional circumstances, and it must be accompanied by a meet-and-confer declaration.
Under section 2034.620, the court will grant the motion only if the opposing party’s reliance on the existing list won’t be unfairly prejudiced, and either the moving party could not with reasonable diligence have identified the expert earlier or the failure was the result of mistake, inadvertence, surprise, or excusable neglect.10Justia. California Code of Civil Procedure 2034.610-2034.630 Relief typically comes with conditions, such as making the expert immediately available for deposition, letting the opposing party designate experts in response, or continuing the trial date. The augmentation process is a safety valve, not a workaround for missing the exchange date.