---

An expert retained and designated by one spouse may ultimately provide an opinion that helps the other spouse. Under appropriate circumstances, the nondesignating spouse may be able to call that expert as a witness.

Designation Can Make the Expert Available

Once an expert has been properly designated for trial, the opposing party may obtain discovery concerning the expert’s opinions, supporting information, and produced materials. The expert’s deposition can clarify whether the opinion supports or undermines either party’s position.

The spouse who retained the expert should not assume that deciding not to call the expert will necessarily prevent the other side from using the testimony.

A Deposition Is Usually Important

The nondesignating party may call the other party’s expert when the expert has been deposed. The deposition establishes the opinions reached, their factual basis, and the scope of testimony that may be offered.

For this reason, a party deciding whether to depose an opposing expert should consider more than cross-examination. The testimony may become affirmative evidence if it supports the party’s valuation, tracing, income, or other position.

Impeachment Testimony Has a Narrower Scope

An expert may sometimes be used to impeach another expert’s testimony even without having been designated by the calling party. This exception is limited.

An undesignated impeachment expert may address the falsity or nonexistence of a foundational fact relied upon by the testifying expert. The witness cannot simply present a competing opinion under the label of impeachment.

Expert Strategy Can Change Before Trial

An expert’s analysis may evolve after additional records, corrections, or deposition questioning. Parties should evaluate the final opinion rather than assuming the expert will remain aligned with the side that originally retained them.

Compensation, scheduling, document production, and the permissible scope of testimony must also be addressed. The court retains authority to apply the expert-disclosure rules and control the evidence presented at trial.

A California family-law attorney can examine the opposing expert, determine whether the testimony benefits the client, satisfy the requirements for calling that witness, and distinguish permissible expert evidence from improper undisclosed rebuttal.