Who is an expert witness?

In personal injury cases and other torts cases, “experts” are often consulted. An “expert” is a person with particular knowledge of a certain subject. For instance, physicians are often called as experts in personal injury cases to explain how the plaintiff was injured, what was used to treat the injury, and how the plaintiff can expect the injury to affect the rest of her life. Experts who give testimony, either during a deposition or at trial, are known as “expert witnesses.”

An expert consulted in a personal injury case does not have to be a witness. If a plaintiff’s or defendant’s attorney wishes to consult an expert privately as a way of clearing up some confusing point or considering what strategy to use at trial, the conversation between the attorney and the expert may be kept confidential under the attorney work-product doctrine.

If the attorney wants to use information from the expert at trial, however, the information must be disclosed to both the plaintiff and the defendant as part of discovery. The required information includes the name and contact information of the expert, as well as a report from the expert that explains what evidence the expert looked at and what her professional opinion is based on that evidence. In most states, these reports are meant to be exchanged before the expert is questioned during a deposition. In reality, however, reports are more likely to be exchanged either at the deposition itself or afterward, due to the time constraints involved.

Depositions for expert witnesses involve different questions from depositions for lay witnesses. For instance, since the rules of evidence require a party offering an expert to first establish that the person has expertise in her field, both the deposition and the testimony given at trial will often begin with the attorneys questioning the expert about her background, education, work experience, certifications, and other professional credentials. Expert witnesses are often asked to provide a copy of their resume or curriculum vitae (CV) before the deposition, and this document is frequently added to the deposition as an exhibit so that it becomes part of the trial record.

At trial, the party or attorney who brought the expert into the case is usually the first to question the expert during direct examination. In these questions, the attorney must first establish that the expert has the “knowledge, skill, experience, training, or education” needed to help the judge or jury understand elements of the case that are too specialized for the average person to be expected to know, according to the Federal Rules of Evidence. For this reason, physicians are common expert witnesses in personal injury cases. In a products liability case, experts may also include engineers or other experts who can testify as to whether or not a particular product was defective and, if so, how it should have been put together to make it properly safe.

Also, during direct examination, the attorney may ask the expert witness for his personal opinion about the facts of the case that are his specialty. For instance, the attorney may ask a physician who is an expert witness whether, in her professional opinion, the plaintiff will ever be able to walk again. In a products liability case, the attorney may ask an engineer whether, in her professional opinion, a blade guard on a particular type of power saw adequately protects the user against injuries.

This rule differs from the evidence rules for lay witnesses, who are usually prohibited from expressing a personal opinion. For example, in a car accident case, the plaintiff’s attorney may ask an expert auto mechanic if, in his opinion, the brakes on the defendant’s car were defectively installed so that the defendant could not possibly have stopped the car in time to avoid hitting the plaintiff. However, this attorney may not ask an eyewitness who saw the crash if, in her opinion, the defendant was going “too fast.” This is because expert opinions have a foundation – they are based on the expert’s “knowledge, skill, training, experience, or education” on that subject. Lay witness opinions, on the other hand, are generally based on speculation, which parties may not use as evidence at trial.

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