Some California family law disputes involve questions that require specialized knowledge beyond ordinary testimony. A real estate appraiser may be needed to value a residence, a forensic accountant may analyze a business or trace separate property, and other qualified professionals may provide opinions concerning technical issues. When expert testimony will be presented at trial, California discovery procedures require the parties to address expert witnesses before the expert takes the stand.

Expert Witnesses Provide Specialized Opinions

An expert witness differs from an ordinary fact witness.

A fact witness generally testifies about events personally observed or information personally known. An expert may provide an opinion based on specialized knowledge, training, education, skill, or experience when that expertise will assist the court in understanding an issue.

Expert testimony can be particularly important in California property division.

For example, an appraiser may provide an opinion about the fair market value of real property. A forensic accountant may trace funds through commingled accounts, analyze income available for support, or value a business interest. An expert may also evaluate business goodwill or other financial issues requiring specialized analysis.

Using an expert does not mean that the expert decides the case. The family court determines the disputed issues and decides what weight to give the expert’s opinion along with the other evidence.

Expert Witness Information Is Exchanged Before Trial

California provides a procedure for exchanging expert witness information after a case has been set for trial.

The process allows the parties to learn which experts the other side expects to call. The required exchange includes identification of the expert witnesses a party intends to present.

For retained experts, additional information is generally required. This can include an expert witness declaration describing matters such as the expert’s qualifications, the general substance of the expected testimony, and other required information. Discoverable writings prepared by retained experts must also be exchanged under the applicable procedures.

Different rules apply to certain nonretained experts and court-appointed experts. They do not necessarily require the same declaration or document production that applies to an expert specifically retained in anticipation of litigation or preparation for trial.

The distinctions matter because failing to comply with expert disclosure requirements can affect whether expert testimony is permitted at trial.

The Other Party Can Investigate an Expert’s Opinions

Expert disclosure is not intended merely to provide the other party with a name shortly before trial.

Once the required information is exchanged, expert discovery can allow the opposing party to investigate the expected opinion and its foundation. A retained expert may be deposed before trial, allowing questions about the expert’s conclusions, methodology, assumptions, and supporting materials.

This can be especially important when experts disagree.

For example, competing business valuation experts might reach significantly different conclusions because they used different financial assumptions. Real estate appraisers might disagree about comparable properties or valuation adjustments. Forensic accountants might disagree about whether particular funds were successfully traced to a separate property source.

Pretrial expert discovery allows those disagreements to be identified and examined before the expert testifies in court.

California procedures also permit protective orders in appropriate circumstances involving expert discovery. Simply ignoring a valid expert exchange demand can carry substantial consequences, including possible exclusion of expert testimony.

Conclusion: Expert Evidence Requires Preparation Before the Trial Begins

Expert witnesses can provide important specialized evidence in California family law cases involving property valuation, business interests, tracing, income, and other technical questions. But expert testimony is not simply introduced for the first time at trial. California’s pretrial procedures provide for disclosure of expected experts and, when applicable, their opinions and writings so the opposing party has an opportunity to investigate and respond. Proper expert discovery helps define the technical disputes the family court will ultimately have to decide.