Expert Witness

If you have seen a criminal trial on TV, you have probably seen an expert witness. Experts testify in criminal cases about DNA evidence, blood splatter patterns, or other matters. 

But civil cases also rely on expert witnesses. Your injury case may require testimony from an expert about your accident, the injuries you suffered, and your prognosis. These experts can provide valuable information to jurors to help them decide the facts of the case and the damages you may recover.

What is an Expert Witness?

Witnesses fall into two categories:

Fact Witness (lay witness)

Fact Witness (lay witness)

Fact witnesses testify in court about their direct observations and experiences about an incident. These witnesses can only testify about what they know rather than what they speculate about or believe.

Sometimes, this difference between knowledge and speculation comes down to wording. A judge might not allow a fact witness in a car accident case to say the other driver “was drunk,” but they may allow a fact witness to say the other driver “appeared drunk” or “acted drunk.”

In most injury cases, fact witnesses testify about what they saw before, during, or after an accident. For example, a fact witness might say they saw the other driver run a stop sign right before the crash.

Fact witnesses can also testify about what they later learned. Thus, a crash victim can testify that a doctor diagnosed them with a concussion. The victim does not know this because of their observations but because of what the doctor told them.

Expert Witness

Under the Louisiana Evidence Code, an expert witness gives opinion testimony rather than fact testimony. Thus, expert witnesses will not testify about their observations and experiences at an accident scene. Instead, their testimony will usually include opinions about how the accident happened and what effects it may have on the victim.

Unlike fact witnesses, expert witnesses can testify about speculations or beliefs as long as they have a scientific basis for their testimony. An expert witness could testify in a wrongful death case that they believe the accident victim died from exposure to a toxic substance. But the expert would need to explain the scientific reason for this belief.

Qualifying an Expert Witness

Not everyone can testify as an expert witness. But experts do not need to have a doctorate to qualify as an expert. Instead, Louisiana law gives five grounds for qualifying as an expert:


Someone can become an expert through study. The knowledge they gain can help them provide valuable evidence to a jury even though they never received formal training or education in their field.


Skill often comes through practice. Skills acquired through driving a truck might qualify someone to testify as an expert witness in a truck accident case. Again, the driver might qualify simply due to their prior experience, even if they never took a truck driving course.


Experience, like skill, is gained through practice. Some expertise comes from repetition. The expertise gained through these experiences can qualify someone to render opinion testimony in court.


Training is often equated to education. But some lawyers and judges distinguish between the two using the example of on-the-job training. A mentor or employer can train someone outside of an educational setting. This training may give the worker enough expertise in that field to testify as an expert.


Education is probably the most common way to qualify as an expert. When an expert testifies in court, they will often give a long list of educational institutions they attended and degrees they earned.

Expert Witness Testimony

Expert witnesses can testify about many issues in the case. For example, if you and the other driver dispute how a car crash happened, you can use an expert witness to “reconstruct” the crash. The expert would then testify in court to give their opinion about what happened.

A common use of expert testimony is to inform the jury about your prognosis. Your damages will include your future medical expenses and diminished earning capacity.

In order to measure these losses, the jury must hear about your long-term functional limitations and disabilities. They must also hear about future medical problems you might develop.

To give testimony, the expert must explain to a judge which facts or data the expert used to analyze the issue and the method used in the analysis.

If a judge does not believe the analysis rises to the standard of repeatability, the judge can exclude the expert’s testimony from the court.

Contact an Experienced Injury Lawyer for Help

From accident reconstruction to your functional abilities after your injury, experts can guide a jury in reviewing the evidence. To discuss how an expert witness can help you in your injury case, contact Kenny Habetz Injury Law for a free consultation. We’re standing by to help your claim.