Two lessons emerge from the Appellate Division’s December 5, 2025 opinion in Weissman v. Li. The first is a reiteration of the importance of precision of the language used in questioning witnesses. The other is rejection of the reflexive reluctance to question one’s own witness in a pretrial deposition.

This is a medical malpractice case involving a claim that spinal surgery caused the plaintiff’s leg and foot pain. The plaintiff had a Minimally Invasive Lumbar Decompression (MILD) procedure to treat his spinal stenosis. The trial court excluded the plaintiff’s liability expert, a board-certified anesthesiologist and pain management specialist, from opining on medical causation and then granted summary judgment dismissing the complaint for failure to establish a prima facie case because the plaintiff had no expert testimony to support the essential element of causation.

The trial court reached this conclusion for two reasons. The expert stated in his deposition that he would “defer to a neurologist” regarding causation undermining the witness’ expertise to express an opinion. In addition, the trial judge deemed the expert’s report an inadmissible “net opinion” lacking sufficient factual basis. On appeal, in an opinion authored by Judge Jack M. Sabatino, the Appellate Division affirmed but without endorsing the trial judge’s analysis completely. The court invoked the commonly used deferential standard for review of trial court evidentiary rulings from Townsend v. Pierre that admissibility of expert testimony “is committed to the sound discretion of the trial court” but with de novo review of questions of law. The court framed the pivotal legal issue as whether the plaintiff’s expert satisfied the requirement found at N.J.R.E. 702 that the witness has sufficient expertise to offer the intended testimony.

The plaintiff’s theory of liability was that while performing a surgical procedure on the patient’s spine, the defendant caused an injury to the nerve in the spine. The Appellate Division noted that the expert had extensive training and experience in the fields of anesthesia and pain management, was board-certified in the field, and was manifestly familiar with the nervous system and its effect on pain. He was the sole expert on behalf of the plaintiff. Since the defendant was a board-certified pain management physician, the expert satisfied the requirement of the Patients First Act that a witness opining on medical liability issues must have comparable or equivalent credentials to those of the defendant. The defense had two experts: a board-certified anesthesiologist and pain management specialist and a neurologist. The proffered opinions of the defense experts were that there was no deviation from accepted standards of care in the performance of the procedure and that the procedure did not cause the plaintiff’s leg and foot problems.

Defense counsel conducted a pretrial deposition of the plaintiff’s expert in a fashion to limit the scope of his opinions. In response to questions, the witness acknowledged that nerve injury was a known risk of the MILD procedure. The examination then included the following crucial passage:

Q: Would I be correct, Doctor, that you would defer to a neurologist in terms of whether or not Mr. Weissman’s complaints on the bottom of his foot are related to the surgery or not?

A: Yes, I would defer to a neurologist.

Q: I understand those are your opinions and maybe you just didn’t understand my question, because it could short-circuit the deposition is what I’m trying to do. So if I’m understanding, your role in this case is to give us your opinions as a pain management specialist as to deviation from standard of care. Correct?

A: Yes.

 Q: And I’m correct that in terms of what these alleged deviations caused in terms of any possible neurological damage to the patient, you would defer to a neurologist because that’s not your area of specialty. Correct?

A: Yes.

The trial court concluded that this deposition testimony was a concession by the expert that he was unqualified to opine on the causation issues in this case. On appeal, Judge Sabatino identified the effect of the expert’s concession that he would defer to a neurologist in the evaluation of the cause of the nerve injury as “a matter of first impression” in New Jersey. Although finding no germane precedent in New Jersey case law, he cited decisions from other jurisdictions addressing the issue. He referred to cases from the Tenth Circuit Court of Appeals (applying Kansas law) and from Georgia where an expert was disqualified from testifying on the basis of such a deferral to the expertise of another specialty. But decisions from other jurisdictions, including New Hampshire and Texas, reached a contrary conclusion. In final analysis, the court declined to adopt a blanket rule that such a concession precluded an expert from testifying and described the evaluation as “highly contextual.”

No one asked [the deponent] to define the term “defer” or what he understood the word to      mean in this context. The questioner did not define the term either. The plaintiff’s counsel did       not object to the question.

Nor did the plaintiff’s counsel ask any clarifying questions of the expert after defense counsel   had finished her questioning of Dr. Gerges.

Emphasizing the lack of definition or clarification, Judge Sabatino looked to dictionary usage of the word “defer” and found that these connoted a yielding or submitting to the opinions of another person. He noted that one might infer that the witness was acknowledging to his questioner that he is not a neurologist, and that only a neurologist is qualified to render opinions about whether the MILD procedure medically caused the plaintiff’s foot and leg pain. However, it could also be that he was simply expressing professional respect for the views of neurologists and their specialty. A third interpretation was that as a board-certified anesthesiologist and pain management doctor, he was not as qualified as a neurologist to render opinions about the cause(s) of a patient’s pain but notwithstanding that deference, he nonetheless advanced his own contrary opinions on what caused the plaintiff’s condition. In the context of a summary judgment motion given these various inferences and the need to draw all inferences in favor of the party opposing the motion, the court declined to rest the analysis on the supposed concession.

Rather Judge Sabatino proceeded to review the net opinion aspect of the trial court’s ruling. He concluded that the trial judge had correctly applied the doctrine’s requirement that the expert’s testimony must provide the “whys and wherefores” to support the admissibility of the opinion. The plaintiff’s expert report did not explain anatomically the causal mechanism as to how the spinal procedure produced the problem with a nerve root resulting in weakness of the plaintiff’s leg and pain in the foot. “An expert’s explanation of a causal mechanism is important when it is not obvious to a layperson how an action or inaction can cause an injury.” Since nerve injury is a generally recognized risk of this procedure, the expert did not explain how the risk of such harm in the plaintiff’s case was increased by the defendant’s alleged surgical deviations.  The expert’s discussion of causation was brief and largely a temporal analysis, resting upon what he referred to as the “timing component” of the plaintiff’s symptoms and conditions. But Judge Sabatino explained that “the association or coincidence of the timing doesn’t suffice to prove causation” and referenced the Supreme Court’s decision in State v. Olenowski, one of a line of cases holding that correlation, consistency or association does not equal causation. In Olenowski, while temporarily assigned tothe Supreme Court, Judge Sabatino demonstrated the insufficiency of “mere coincidence”:

A simple example illustrates the point: the fact that, between 1908 and 2020, the same political party’s candidate won the presidential election in two-thirds of the years in which a National League team won the World Series does not mean that the World Series outcome caused the presidential election result. The correlation between those events is obviously coincidental. 

The assertion that because a condition follows some event chronologically, it was caused by that event is the false logic of post hoc, ergo propter hoc rejected in several New Jersey decisions dating back at least to 1961 with Schulman v. Male. Temporal analysis may play a role in cases that qualify for the application of the doctrine of res ipsa loquitur; however, that doctrine is narrowly applied under New Jersey law to medical malpractice claims. Moreover, the doctrine has been held inapplicable to an injury which is a known risk of the surgery or procedure.

Judge Sabatino’s analysis of the supposed concession by the plaintiff’s expert that he was unqualified to opine on causation because he would “defer” to a neurologist illustrated the possible interpretations and resulting ambiguities of the testimony. The use of clear, precise language is essential to avoid misunderstandings and ambiguities, and to effectively communicate recollections and observations. Having a medical witness explain and define technical terminology is basic in trial work. The Appellate Division in its opinion in Ruth v. Fenchel recognized that this could be done by opposing counsel or even the judge at trial. This concern typically revolves around scientific or medical information. But one must be alert for not only for “weasel words” to evade answering a question but also for vague and connotative words capable of multiple meanings. Otherwise, there is a risk of setting the stage at trial for an exchange reminiscent of the scene in Through the Looking-Glass in which Humpty Dumpty said to Alice: “When I use a word, it means just what I choose it to mean — neither more nor less.”

That the plaintiff’s case was made vulnerable by the plaintiff expert’s concession regarding “deferring to a neurologist” is apparent in retrospect; however, that could have been recognized at the deposition table. While long-standing traditional wisdom is to not question one’s own witness at a pretrial deposition, that precept should not be rigidly followed in all situations. As Judge Sabatino commented, there was no objection to the form of the question and neither “did the plaintiff’s counsel ask any clarifying questions of the expert after defense counsel had finished her questioning.” The issue that was problematic at the trial level for the plaintiff could have been avoided. And that same issue that became adverse for the defense on appeal could have been eliminated with more precise follow-up phrasing that committed the witness to a definition of this critical term.