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When pursuing a personal injury claim in California, success often depends on more than just the facts of the accident. Many cases require specialized knowledge that goes beyond the average juror’s experience. That’s where expert witnesses come in. At The Sterling Firm, we know how to strategically use experts to build strong cases, prove damages, and win justice for our clients.

What Is an Expert Witness?

Under California Evidence Code § 720, an expert is anyone with specialized knowledge, skill, training, education, or experience that can help a jury understand issues in dispute. This doesn’t always mean a world-renowned scientist — it could be a treating doctor, an accident reconstructionist, or even a building inspector.

Examples of issues where expert testimony is critical:

Accident reconstruction: Explaining how a car crash occurred.
Biomechanics: Determining whether the forces were enough to cause injuries.
Medical causation: Linking the accident to injuries such as concussions, fractures, or traumatic brain injury.
Life care planning & economics: Proving future medical needs, disability, and lost earnings.
Premises liability & building codes: Showing that dangerous conditions violated safety standards.

Retained vs. Non-Retained Experts

Not all experts are the same. California law distinguishes between:

Retained Experts: Hired specifically for litigation. For example, economists, vocational rehabilitation specialists, or accident reconstruction engineers. Their opinions are formed for the case, and they are compensated for their testimony.
Non-Retained Experts: Professionals who form opinions in the normal course of their duties, not just for trial. For example, treating doctors, EMTs, or mechanics who inspected a vehicle. Juries often find these experts more credible because their opinions are not litigation-driven.

⚖️ Pro Tip for Attorneys: Be careful not to turn a non-retained expert into a retained one by giving them litigation materials. Under Dozier v. Shapiro, doing so can change their designation and even risk exclusion at trial.

The Hearsay Problem: “Rely, Not Relay”

A major issue in expert testimony is hearsay. In California, the case of People v. Sanchez (2016) established that while experts may rely on case-specific hearsay (like medical records or police reports), they cannot relay that hearsay directly to the jury.

Example:

A neurologist can review ER records diagnosing a concussion.
But the neurologist cannot simply tell the jury, “The ER doctor said it was a concussion.”

🔑 Solution: First introduce the foundational testimony through the non-retained doctor (ER physician), then bring in your retained neurologist. Once the evidence is in the record, the retained expert can reference it without hearsay problems.

Locking in Expert Testimony

Another key strategy is controlling the scope of expert testimony. Under Kennemur v. State of California (1982), retained experts are bound by the opinions they give at deposition. That’s why at deposition, plaintiff’s counsel should always ask:

Have you given all the opinions you intend to give at trial?
Have you explained the basis for those opinions?
If new opinions arise, will you notify us so we can depose you again?

This locks the expert into their testimony and prevents surprises at trial.

Why Non-Retained Experts Are So Powerful

In personal injury cases, treating doctors and other non-retained experts are often your strongest witnesses. They treated the plaintiff in real time, before litigation ever began. Their testimony on diagnosis, treatment, and causation can carry immense weight.

California courts in Sheiber v. Kiser and Ochoa v. Dorado confirmed that treating doctors may testify on causation and standard of care when opinions were formed in the course of treatment.

Practical Tips for Using Experts

Switch up retained experts: Using the same doctor or economist in every case may look biased to juries. Rotate your roster when possible.
Videotape depositions: Always preserve testimony. Conduct a mini-direct at the end in case the witness can’t appear at trial.
Be strategic with designations: Don’t over-list every provider. Only designate those who strengthen your case, otherwise the defense may use less helpful ones against you.
Foundation first: Sequence matters. Lay groundwork with non-retained experts, then bring in retained experts to expand on those opinions.

Why This Matters for Clients

For injured victims, the use of experts may determine whether you win your case and how much compensation you receive. Experts help:

Prove the accident caused your injuries.
Establish the cost of your future medical treatment.
Calculate your lost wages and reduced earning capacity.
Show the jury the true impact of your injuries on your life.

At The Sterling Firm, we carefully select and prepare expert witnesses so that your story is presented powerfully and persuasively in court. Different cases require different types of experts. For example, to learn more information about what experts are needed to win a premises liability case, please see Premises Liability Expert. It is also important to know how to take the deposition and cross examine the opposing defendant’s experts, such as during cases involving traumatic brain injury defense expert.

Call The Sterling Firm Today

If you or a loved one has suffered serious injuries in California, don’t leave your case to chance. To learn more about proving the value of your personal injury case, please see How To Prove Pain And Suffering. The defense will bring their own experts to minimize your claim — you need a law firm that knows how to fight back. Contact us today to speak with a Personal Injury Lawyer.

Call or Text us 24/7: (310) 498-2750
Toll Free: (844) 4-GETLEGAL (844-443-8534)