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Are Experts Needed for Res Ipsa Cases?

February 7, 2013

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The New Jersey Appellate Division recently handed down a decision that clarifies when expert testimony is required in <i>res ipsa loquitur</i> cases, and when the doctrine may be applied.  In certain cases where the cause of an accident is not entirely clear, this doctrine allows a permissive presumption that a defendant breached a duty of care owed to a plaintiff based upon how an accident occurred, provided certain required factors are present.  The jury is then free to accept or reject the presumption.
In <a href="" target="_blank" rel="noopener"><i>Mayer v. Once Upon A Rose, Inc.</i>,</a> the plaintiff, a caterer, claimed that he had been injured while setting up for an engagement party.  The defendant, an employee of a florist who was also setting up a display for the engagement party, was carrying a heavy vase that the florist had used on several previous occasions.  The plaintiff and defendant set forth different versions of how the defendant was holding the vase at the time the accident occurred.  However, the uncontroverted evidence was that the vase shattered while the defendant was holding it, and that the plaintiff was cut by shards of glass from the broken vase.
At trial, the plaintiff did not present an expert on the issue of how the glass vase shattered, arguing <em>res ipsa </em>allowed jurors to presume defendant must have been negligent in some way for the vase to have shattered.  The court granted a motion for a directed verdict made by the defendant at the end of the plaintiff’s case, finding the failure to present expert testimony on the issue was fatal to the plaintiff’s case.  The trial judge also opined that it was unclear whether <i>res ipsa loquitur</i> applied to these circumstances.
On review, the New Jersey Appellate Division reversed the order for a directed verdict and remanded the matter for a new trial.  The Appellate Division, citing New Jersey Supreme Court precedent, stated that expert testimony is not necessary in all cases where the <i>res ipsa loquitur</i> doctrine is invoked.  In fact, as long as, based upon <i>common knowledge</i>, the balance of the probabilities in the case favors negligence on the part of the defendant, expert testimony is not necessary.  In essence, if the average juror is able to deduce how the accident occurred without needing to resort to specialized knowledge, then expert testimony is not required.
Additionally, because this case involved a glass vase that was in the exclusive control of the defendant, the Appellate Division held that the doctrine of <i>res ipsa loquitur</i> could apply to these circumstances.  The jury would be permitted to infer that the defendant was somehow negligent, causing the vase to shatter.
The <i>Mayer</i> decision demonstrates that, much like in other areas of the law, expert testimony is only required in cases invoking the doctrine of <i>res ipsa loquitur</i> when the subject matter falls outside the ken of the average juror.
Thanks to Christina Emerson for her contribution to this post.  If you would like more information please write to


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