Proving Medical Causation And Damages: How Personal Injury Differs From Workers’ Comp

When you are asked to testify as to the causes and effects of a patient’s injuries, bear in mind that standards of proof vary depending on what legal forum you are in.

If your patient is suing someone for negligently causing his/her injuries, the standard may differ from that applied if your patient is trying to prove a work injury. Since we have devoted much attention in the pages of this JOURNAL to explaining the standard of “major contributing cause,” as it applies to prove a work injury is compensable, we now want to explain the different standard of causation in personal injury claims.


When your patient is claiming another person negligently “caused” his or her injury, your patient need only show that the act or omission was a substantial factor in producing the injury and damage. A “substantial factor” is an important factor or a material factor. It must be more than an insignificant factor. However, it need not be the “major” factor.

Therefore, if you are being asked to address the causal relationship between a motor vehicle accident, for example, and your patient’s injuries, your testimony that the accident was a material or greater causal factor is the evidence the court needs to decide your patient has a viable claim. Even if other factors, including your patient’s physical condition just prior to the accident, contribute more to your patient’s injuries than the accident itself, your patient’s causation claim is sound, as long as the accident was a material or substantial factor. The jury, of course, makes the final decision, after receiving instructions from the judge on this standard.

Therefore, when testifying in a personal injury case, you will not be called upon to render an opinion on what percentage the accident contributed as compared to a “pre-existing condition,” as you may be asked in a workers’ compensation matter. By the same token, your medical evidence of cause in a personal injury dispute will not require an opinion as to whether the injury “combined with” a pre-existing condition to become the “major cause” of your patient’s disability or need for treatment.

However, if the negligently caused injury aggravated your patient’s pre-existing injury or disability, your patient is entitled to reasonable compensation for the consequences of such aggravation resulting from the negligent act. Therefore, you may he asked to help the court identify the specific consequences of such an aggravation and to separate them from the injury or disability which already existed. You will, of course, want to review the medical records of the pre-existing injury or disability, especially if you were not the treating doctor.


On the other hand, even if your patient involved in a personal injury claim already had a bodily condition which predisposed him/her to be more subject to injury, the negligent person causing the injury is still liable for all injuries and damages your patient has suffered. This is true even though the injuries to your patient are greater because of your patient’s condition than the injuries that would have been suffered by another person under the same circumstances.

This is different from Workers’ Compensation claims where such pre-dispositions are part of the definition of “pre-existing condition,” requiring your medical opinion as to whether it “combined with” the injury to become the major contributing cause of your patient’s disability or need for treatment.



Another major difference between personal injury actions and Workers’ Compensation claims is that comp claimants are not compensated for “pain and suffering.” However, once it is established that the other party caused the injuries, the personal injury claimant is entitled to an award of damages for pain and suffering. These include not only the sensations resulting from physical injury, but also mental suffering and anguish such as fright, fear, shock, apprehension, worry, anxiety and other forms of emotional distress caused by physical injury.

The damage award for pain and suffering is measured by the nature, extent, severity, duration, and effect of the injuries. Assigning a value to the damage award involves consideration of: 1) pain suffered at the moment of impact; 2) pain suffered from the time of impact until medical treatment was obtained; 3) pain incident to medical treatment and any surgery necessitated by the injury; 4) pain suffered during hospitalization; 5) pain suffered up to the time of trial; 6) present pain; and 7) reasonably probable future pain and suffering.

You may be asked for an opinion on whether your patient’s injuries are permanent and whether they are expected to cause future pain and suffering. In the eyes of the law, permanent injury usually involves future pain and suffering. However, future pain and suffering does not necessarily mean the injury is permanent, which is generally defined as lasting for the rest of the injured person’s life.

Pain and suffering and other future damages are discussed further in the article on damages in this JOURNAL.


You should be prepared to give and explain your opinion as to the “reasonable medical probability” that 1) the incident in question caused the injuries; 2) the injuries will cause future pain and suffering; and 3) the injuries will be permanent. Your opinion may be based on the results you have observed in others who had suffered similar injuries.

When addressing the future course of the injury, be sure to state whether this injury will make your patient susceptible to contracting any disease or incurring other injuries or conditions.

Medical testimony is required if the injury is complicated, symptoms do not appear immediately, medical treatment is delayed, or the injured person has previous injuries similar to the present injuries.

When the questions of the future course of treatment, pain and permanency are in issue, it is best for you to examine your injured patient shortly before trial. Also, a meeting with the attorney is usually arranged before trial.

Be sure to ask the attorney what questions and standard of proof you will be asked to address. Knowing ahead of time the questions you will be asked and the standard used to evaluate your answers will help you focus your preparation. Also, it will help insure that your answers genuinely assist the court in applying the law to your patient’s injuries.

This article was prepared by Dennis H. Black.