A woman in a dark suit giving testimony in court.

Medical Expert Witnesses

Exploring Their Critical Role in Medical Malpractice Litigation

Expert testimonies are an essential part of any medical malpractice case. But how do attorneys find them and what makes them credible?

Medical malpractice cases nearly always involve evaluating complex technical questions that are at the heart of treatment decisions. Yet, cases that go to trial are decided by juries comprised of people with no medical training. This raises the question:  How are non-medical professionals expected to accurately and fairly decide whether a physician committed malpractice? The answer is that testimony from expert witnesses helps jurors understand the issues and reach a verdict. This article explains the role expert witnesses play in malpractice litigation, the qualifications needed to serve as an expert witness, and the characteristic that make an expert witness effective at trial.

Why are Expert Witnesses Unique?

Normally, witnesses providing testimony at a trial are limited to talking about their personal knowledge of information related to a case and can offer opinions only in specific, limited circumstances.1 Additionally, lay witnesses cannot testify about scientific or technical principles outside the common understanding of the average person. By contrast, expert witnesses are allowed to offer their opinions on a case based on an after the fact review of what transpired and are not limited to their personal knowledge of the case. The opinions and conclusions made by experts will often involve technical questions or abstract principles. In other words, lay witnesses are largely limited to testifying about their personal perception of what happened. By contrast, expert witnesses are allowed to testify in the form of opinions about what could or should happen in a specific situation.


Consider a hypothetical lawsuit in which a plaintiff is claiming that he suffered abdominal pain and that the defendant physician failed to diagnosis and treat the cause of the pain. In a case like this, if the plaintiff does not have medical training, he would be permitted to testify about his subjective experience of his pain and his recollection of interactions with the defendant physician. The plaintiff would not be allowed to speculate about what caused his pain, what the physician should have done differently or how his condition would have been impacted by earlier treatment. Explanations of disease processes, the effectiveness of available treatments and the correct methodology for diagnosing the cause of an illness are all matters that can be addresses only by a properly qualified expert.

An expert witness can be asked to testify about the generally accepted practices for evaluating and treating a patient’s complaint of abdominal pain, how treatment would impact a disease process, and offer an opinion as to a patient’s prognosis. This testimony would not necessarily be based on the facts of the case. Rather, the basis for the testimony would be the expert’s familiarity with accepted practices and experience with treating similar ailments in the past. An expert witness in the abdominal pain case could also be asked whether the defendant physician’s decisions were consistent with generally accepted practices.

What Qualifications are Required to Act as an Expert Witness?

Before a witness is permitted to offer an expert opinion, the witness’s qualifications must be established. This usually involves the witness providing information related to her experience, education and training. In short, an expert witness is someone who has specialized skill, knowledge, education, experience or training.2 To be presented to a jury, the basis of an expert’s opinion must be grounded in the proper application of well-accepted principles and methodologies. If an expert lacks experience, education or training on the subject matter of their testimony, or if the expert is using a novel theory or standard, a court may deem the expert unqualified and refuse to allow the expert to testify.3

However, it should be noted that the standard used to evaluate the admissibility of expert testimony is flexible. While education and training are a typical qualification of an expert, they are by no means a requirement.


A classic example of this principle comes from a case centering on a dispute over the sale of a hunting dog. The plaintiff in the case claimed that he purchased a dog from the defendant after being misled about the dog being an excellent bird dog. To support his case, the plaintiff put on testimony from a hunting dog expert. Notably, this expert had no education past the 8th grade and no formal training related to canines. Despite this, the plaintiff’s expert witness was permitted to testify about the dog’s ineffectiveness as a bird dog because of the expert’s decades of experience with breeding, training and selling similar animals. This example demonstrates that the specific nature of the dispute in a case will determine the type of qualifications necessary to be allowed to offer expert testimony at trial.

In the context of medical malpractice litigation, a complete lack of education or formal training would bar a person from offering expert testimony. Typically, any opinion on treatment decisions or a diagnosis must come from a licensed physician. However, there are many nuances that can impact whether a proposed expert will be permitted to offer testimony in a medical malpractice case. In general, before an expert witness can offer an opinion on a medical professional’s treatment decisions, the proposed expert must show that they practice in the same or a substantially similar specialty to that of the health care professional accused of malpractice, or otherwise have familiarity with the medical issues involved in the case.

For instance, in a case involving an emergency room physician accused of failing to timely diagnose an aortic dissection, a board-certified cardiothoracic surgeon was not permitted to offer testimony criticizing the emergency room doctor.4 The basis for excluding the surgeon’s testimony was that the surgeon lacked experience evaluating patients in an emergency room setting. By contrast, in a case arising from alleged negligence by an orthopedic surgeon in the application of a cast on the plaintiff’s leg, a podiatrist was permitted to offer testimony on the proper standard of care.5 Even though podiatry and orthopedic surgery are obviously distinct medical specialties, the podiatrist was permitted to testify because he regularly applied and removed casts as part of his practice and had been trained on the procedures at issue. These examples illustrate the importance of selecting a professional with the correct qualifications to serve as an expert in a case.

Additionally, many states have created requirements that must be met before an expert witness is permitted to criticize a treatment provider’s care. These rules are often aimed at eliminating so-called “professional witnesses,” who make a career out of reviewing cases and providing opinions in malpractice cases. Generally, these rules require that a medical professional must spend a majority of her time practicing medicine or teaching at an accredited medical school to be permitted to offer expert testimony at the trial of a medical malpractice claim. Adeptly navigating the various requirements related to expert witness testimony is critical to effective legal representation in medical malpractice cases.

Continue to Part 2


  • 1. Fed. R. Evid. 701
  • 2. Fed. R. Evid. 702
  • 3. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509, U.S. 579 (1993)
  • 4. Taulbee v. Dunsky, 12th Dist. Butler No. CA2003-03-059, 2003-Ohio-5988
  • 5. Alexander v. Mt. Caramel Med. Ctr., 56 Ohio St.2d 155, 160 (1978)