How an Expert Medical Witness Shows Negligence

Nearly all medical malpractice cases require the testimony of an expert witness.

By , J.D., University of San Francisco School of Law
Updated by Stacy Barrett, Attorney (UC Law San Francisco)

Medical malpractice happens when a patient is harmed because a medical professional fails to act with the skill and care that a similarly-trained professional would've shown under the circumstances (called the "standard of care").

Patients who sue ("plaintiffs") medical professionals for malpractice ("defendants") almost always have to use medical experts to testify about:

  • the applicable standard of care
  • how the defendant fell short of the standard, and
  • how the defendant's sub-standard care caused the plaintiff harm.

In this article, we'll explain why expert testimony is so critical in malpractice cases. We'll also cover who is qualified to be an expert, the best way to find the right expert for your case, and how to get a medical malpractice claim started.

Why Medical Expert Testimony Is Necessary

Medical malpractice cases are famously challenging for patients to win. Most states require malpractice plaintiffs to overcome a few procedural hurdles—called pre-filing requirements—before they can sue doctors, nurses, or other medical professionals for malpractice.

Pre-filing requirements vary from state to state. Some states require patients to send a notice of intent to sue before filing a lawsuit. More than half of all states require patients to get an expert opinion in the form of a certificate of merit or a review by a panel of independent medical experts before they can even file a lawsuit.

Let's take a closer look at why expert testimony is necessary to win nearly every medical malpractice case.

Experts Can Prove the Standard of Care

The "medical standard of care" is the yardstick by which a medical professional's conduct is measured. Simply put, a medical professional has a legal duty to provide the same care that a competent, careful, similarly-trained professional in the same community would've provided.

An expert medical witness's first task is to establish the relevant standard of care. Only a medical expert can testify about the diagnostic and treatment process that a clinician should follow for a certain type of patient, illness, or clinical situation.

For example, let's say that a patient with pain and swelling in his leg caused by deep vein thrombosis (DVT) goes to see his primary care doctor. The doctor fails to diagnose DVT. One week later, the blood clot is dislodged, leading to a pulmonary embolism and the near-death of the patient.

In a medical malpractice claim against his primary doctor, the patient would need a medical expert to testify about what a typical primary care doctor in the community would've done if presented with the same symptoms. What tests and treatments would a doctor with the same training and experience have offered?

Experts typically rely on their own training and experience as a basis for their opinion about the standard of care as well as medical publications and medical board guidelines.

Experts Can Show a Violation (Breach) of the Standard of Care

Next, the plaintiff's expert medical witness will offer an opinion about the defendant's actions (or failure to act) in light of the medical standard of care. Some examples of medical malpractice include:

  • failing to diagnose an injury or condition
  • failing to treat an injury or condition
  • failing to properly train or supervise staff, and
  • lack of informed consent.

Returning to our DVT example, a medical expert would establish the standard of care for a primary care doctor who was treating a patient with the same symptoms as the plaintiff. If the defendant didn't run the same tests and provide the same treatments that a reasonably competent doctor would've offered, the expert will offer the opinion that the defendant violated (breached) the standard of care (called "medical negligence").

Defendants, of course, almost always hire their own experts to testify that they did, in fact, meet the standard of care. Every aspect of the case, including the plaintiff's medical records, will be scrutinized by the expert witnesses hired by both sides of the case.

When a close case involves complex medical testimony by each side's expert witnesses—a so-called "battle of the experts"— the outcome of the case often turns on which expert the jury finds most credible.

Experts Can Prove Causation

Receiving sub-standard care isn't enough to win a medical malpractice claim. The sub-standard care must have harmed the plaintiff in some way for a plaintiff to receive compensation (called "damages").

Proving causation—the link between the sub-standard care and the plaintiff's harm—can be difficult. Was the bad outcome caused by the defendant or was it inevitable? Returning, again, to our DVT example, the plaintiff would need an expert to testify that had the primary care doctor run the right tests and offered the right treatment, the pulmonary embolism would've been prevented.

Who Is Qualified to Be a Medical Expert?

Each state has its own medical expert requirements. Experts typically have to share the same field of medicine as the defendant, often in the same geographic area.

The most effective experts are doctors, nurses, and other professionals who are still practicing in their field. Not only are they more informed about the current standard of care, but judges and jurors tend to find practicing professionals more believable than so-called "hired guns," whose sole source of income is testifying in court.

Beyond the minimum legal requirements for qualifying as a medical expert in court, plaintiffs and defendants tend to look for experts who are:

  • board certified
  • distinguished in their field
  • effective communicators
  • experienced witnesses, and
  • published in professional journals and books.

Judges and jurors aren't required to accept an expert's opinion. As with any other witness, it's up to each fact finder to decide whether to believe the expert's testimony, which is why finding the right expert can make or break your medical malpractice case.

How Soon Do I Need a Medical Expert?

As noted, dozens of states require experts to weigh in before a plaintiff can even file a medical malpractice lawsuit. Some states require plaintiffs to file a "certificate of merit" with their complaint stating that the plaintiff has consulted with an expert who has concluded that there is a reasonable basis for the lawsuit.

Other states have medical review panels that review potential medical malpractice cases and decide whether the claim is viable. The panel's decision isn't binding, meaning the panel can't prevent a plaintiff from filing a lawsuit. But the findings of the review panel can be presented in court, which poses obvious problems for plaintiffs whose cases are rejected by the panel.

Even when experts aren't required to get a medical malpractice lawsuit started, the sooner you can find an expert the better. An expert can help you and your lawyer:

A Lawyer Can Help You Find the Right Experts

You can file a medical malpractice lawsuit without a lawyer, but working with a lawyer who specializes in medical malpractice cases will get you the best possible outcome in your case.

A lawyer can help you navigate your state's special rules and deadlines for medical malpractice cases and help you find qualified and credible experts. Malpractice lawyers have an extensive network of experts and know which ones testify well in court and which ones only look good on paper.

Next Steps

To get your medical malpractice claim started:

  1. Figure out the time limit to file a medical malpractice lawsuit in your state.
  2. Understand what you need to prove to win your malpractice claim.
  3. Face the challenges of winning a medical malpractice lawsuit.
  4. Learn more about how to find the right lawyer for your medical malpractice claim.

When you're ready, you can connect with a lawyer directly from this page for free.

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