Yes, expert testimony is required in the vast majority of medical malpractice cases. Physicians are held to the standard of care of similar physicians generally in their locale. This means that a radiologist in Nebraska is held to the standard of care for radiologists in that area of the country—not the prevailing standard at John Hopkins Medical Center in Baltimore.

However, some egregious examples of malpractice do not require expert testimony because a layperson can tell that there has been malpractice. This is sometimes called the “common knowledge” exception for cases of extreme and obvious malpractice. Examples include failing to remove a surgical instrument from a patient’s body following a procedure or amputating the wrong arm or leg.

Different states also have special rules regarding expert witnesses in medical malpractice cases. For example, Tennessee has something called the “contiguous state” rule. This means that an expert must be licensed from Tennessee or a state that is contiguous (a state that borders) to Tennessee.