Law & Medicine

Dispensing with expert testimony



Notwithstanding an initial jury verdict in favor of the plaintiff’s children, awarding each of the three children $365,000, the defendants filed a so-called JNOV motion (current term is “judgment as a matter of law”) to negate the jury verdict, on the basis that the plaintiffs failed to present competent expert testimony at trial to prove causation.

The plaintiffs countered that the cause of death was within the realm of common knowledge, thus no expert was necessary. They asserted that “any lay person can easily grasp the concept that a person dies from losing so much blood that multiple organs fail to perform their functions.” Mr. Barbee’s death thus was not “of such a technical nature that lay persons are incompetent to draw their own conclusions from facts presented without aid.”

Hawaii’s Intermediate Court of Appeals disagreed with the plaintiffs, holding that although “Hawaii does recognize a ‘common knowledge’ exception to the requirement that a plaintiff must introduce expert medical testimony on causation … this exception is rare in application.” The court asserted that the causal link between any alleged negligence and Mr. Barbee’s death 17 months later is not within the realm of common knowledge.

It reasoned that the long-term effects of internal bleeding are not so widely known as to be analogous to leaving a sponge within a patient or removing the wrong limb during an amputation. Moreover, Mr. Barbee had a long history of preexisting conditions, including hypertension, diabetes, and cancer. He also suffered numerous and serious postoperative medical conditions, including a stroke and surgery to remove part of his intestine, which had become gangrenous.

Thus, the role that preexisting conditions and/or the subsequent complications of this type played in Mr. Barbee’s death was not within the knowledge of the average layperson.

The “common knowledge” rule is aligned with, though not identical to, the res doctrine, but courts are known to conflate the two legal principles, often using them interchangeably.4

Strictly speaking, the “common knowledge” waiver comes into play where direct evidence of negligent conduct lies within the realm of everyday lay knowledge that the physician had deviated from common practice. It may or may not address the causation issue.

On the other hand, res is successfully invoked when, despite no direct evidence of negligence and causation, the circumstances surrounding the injury are such that the plaintiff’s case can go to the jury without expert testimony.


1. Ybarra v. Spangard, 154 P.2d 687 (Cal. 1944).

2. James v. Wormuth, 997 N.E.2d 133 (N.Y. 2013).

3. Barbee v. Queen’s Medical Center, 119 Haw 136 (2008).

4. Spinner, Amanda E. Common Ignorance: Medical Malpractice Law and the Misconceived Application of the “Common Knowledge” and “Res Ipsa Loquitur” Doctrines.” Touro Law Review: Vol. 31: No. 3, Article 15. Available at

Dr. Tan is professor emeritus of medicine and former adjunct professor of law at the University of Hawaii, and currently directs the St. Francis International Center for Healthcare Ethics in Honolulu. This article is meant to be educational and does not constitute medical, ethical, or legal advice. Some of the articles in this series are adapted from the author’s 2006 book, “Medical Malpractice: Understanding the Law, Managing the Risk,” and his 2012 Halsbury treatise, “Medical Negligence and Professional Misconduct.” For additional information, readers may contact the author at


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