The Role of Experts in Personal Injury Cases

Expert witnesses play a critical role in a personal injury case. They are highly qualified professionals who provide testimony based on their knowledge, skill, and experience about the issues at trial.

Two Kinds of Experts

Missouri classifies experts as non-retained or retained. Non-retained experts have specialized qualifications but are witnesses because they played a role in providing services to the plaintiff. Non-retained experts include EMS technicians, law enforcement, and treating physicians.

Retained experts also have specialized knowledge in their particular areas of expertise. However, they are witnesses for a party because the party’s lawyer hired them to be part of their case. They can testify to facts or make estimates that non-retained experts may not be qualified to do. For example, in vehicle accident cases, the plaintiff may need to prove their future medical expenses or lost earning capacity. That likely would require a retained expert.

Qualifications of Expert Witnesses

Not anyone can testify as an expert. 

Missouri law has the following requirements for them:

  • The witness must be qualified as an expert “by knowledge, skill, training, or education;”
  • The expert’s specialized knowledge must help the judge or jury understand the evidence or facts;
  • They must have enough facts or data to support the testimony;
  • The testimony must be based on solid principles and methods; and
  • The expert must have “reliably applied the principles and methods to the facts of the case.”

Types of Expert Witnesses

Experts are available in many fields.


Medical issues can make up a significant portion of a personal injury claim. But lost earning capacity is also an important category of damages. An economist can provide testimony on topics necessary to estimate a plaintiff’s lost earnings due to an injury, like their reduced ability to perform their job.

ECU Specialist

Semi-trucks manufactured today have electronic control units (ECUs). These monitoring systems gather information about the speed, braking, and stopping actions of the truck.

Manufacturers initially installed ECUs to protect themselves against warranty claims, but they are also useful in a personal injury claim. The collected data can help establish issues like driver error, driver fatigue, poor maintenance, and violations of federal motor safety regulations.


Plaintiffs frequently suffer injuries to the brain, nerve and spinal cord. These types of injuries are common in automobile accidents and can cause chronic pain and other complications for the rest of the victim’s life. A neurologist can testify to the degree of injury, level of disability, and any future medical care needed.

Non-Retained Experts

Police, firefighters, and EMTs can provide information about the accidents they’ve witnessed. The treating medical professionals can give evidence about the plaintiff’s injuries. These witnesses usually have good credibility with the jury.


Orthopedics is the branch of medicine concerned with the correction of deformities in muscles or bones. An orthopedist often treats injuries like spinal injuries, joint surgery, and hip replacement. An orthopedist provides expert testimony about these types of injuries and information on the level of disability and medical needs in the future.

Pain Management Specialist

A serious accident can leave the plaintiff with chronic pain for the rest of their life. Pain management specialists testify about how much pain an injury victim has suffered, its impact on their quality of life, and the costs of pain medication and treatment in the future.

Phone Forensics Specialist

A defendant talking or texting on a smartphone can often cause car accidents. Proving this, however, can be difficult. A phone forensics specialist can access smartphone records to determine whether the accident occurred while the defendant was talking or texting on their phone.

Rehabilitation Specialist

A person involved in an accident who loses functional abilities or even the loss of a body part requires a lot of rehabilitation for life to return to some semblance of normalcy. A rehabilitation expert can provide information about needed prosthetics and the cost of future rehabilitation requirements.

Semi-Truck Maintenance Specialist

Semi-truck accidents are usually more complicated than a typical two-car accident on a city road. A specialist in the maintenance of semi-trucks is able to testify about stopping distances and turning radiuses. They can also discuss a semi-truck’s maintenance requirements and whether the truck company met those requirements.


All too many accidents occur because the defendant was using drugs, whether legal or illegal, at the time of the incident. A toxicologist can testify on critical topics such as adverse drug reactions, poisoning, and overdosing. They can also speak to longer-term issues due to drug use, like causation of lung fibrosis or lymphoma.

Transportation Safety Specialist

Today’s cars and trucks have many safety measures. These include airbags, brake assistance, and forward-collision warning systems. A transportation safety specialist can testify whether a safety precaution was property installed or appropriately maintained.

The Right Expert for You

Our personal injury lawyer in St. Louis at Bradley Law Personal Injury Lawyers is an expert in these cases. They also have the critical connections and knowledge to get you the best expert witnesses to help prove your case. So contact us today for help.