Plaintiff Joseph Costigan was walking on the sidewalk in front of the home of the defendants Gurprit and Sneh Bains when he slipped and fell on a patch of ice and struck his head. He claimed that the drainage system on defendants’ property, that ran down the driveway and across the sidewalk, was faulty and caused the ice. The issue in Costigan v. Bains, 2025 N.J. Super. Unpub. LEXIS 2091 (App. Div. Oct. 29, 2025) was whether the plaintiff needed an expert to support the theory that the drainage system caused the water to collect on the sidewalk, which could be a hazard when the weather was cold.
Plaintiff had retained Mark Marpet, Ph.D., P.E. as an engineering expert who issued a report that the defendants’ drainage system created a hazard by leading the drain water from the gutters and basement sump pump onto the driveway and sidewalk, where it could freeze and create a slip hazard. In his opinion, the elements did not cause the hazard because it had been two days before the accident since any precipitation fell.
Defendants retained the services of Stephen Pellettiere, a certified meteorologist, to provide an expert opinion regarding the weather conditions on the day of the accident. He relied on certified weather reports from the National Oceanic & Atmospheric Administration (NOAA) and opined that there had been a winter storm and snow/ice event on the day of the incident with approximately a half inch of snow on the ground when plaintiff slipped and fell. He disagreed with Dr. Marpet’s report that it was not snowing at the time and noted that Dr. Marpet used erroneous weather underground data that contradicted the certified NOAH observations. In Mr. Pellettiere’s opinion, it was highly unlikely that preexisting ice and snow was in place at the time of the incident because of rainfall of less than an inch ending 40 hours before the incident and temperatures were well above freezing after the rain had ended two days before the incident.
At the trial court level, the defendants filed a motion to strike Dr. Marpet’s report as a net opinion and asked for a summary judgment dismissal. They argued that Dr. Marpet’s opinion that the drainage system created a hazard “lacked any measurements or demonstration of any slopes or angles or anything about water capacity and failed to provide any discussion about the sidewalk.” Further, defendants argued that Dr. Marpet used erroneous data indicating there was no precipitation on the day of the fall when in fact there was an ongoing storm. Defendants further argued that Dr. Marpet’s opinion failed to satisfy any of the requirements for an expert report because it contained “nothing but his pure conclusions.”
The trial court heard the arguments and agreed with the defendants, granting defendants’ motion to strike Dr. Marpet’s report as a net opinion and also granted a summary judgment dismissal. The trial court found that Dr. Marpet’s report “constituted an inadmissible net opinion because it failed to explain the pertinent scientific principles and how he applied them to formulate the basis for his opinion.” The trial court further noted that “Dr. Marpet did not analyze the rates of evaporation for rain water under the conditions of freezing temperatures, provide any measurements of the slope of defendants’ property, calculate the volume of water that could have exited the drain, or author scientific support from a qualified meteorologist.” Thus, the trial court determined that Dr. Marpet did not provide the “why and wherefore of his opinion but rather offered only a mere conclusion.”
As for the summary judgment dismissal, because the trial court found that Dr. Marpet’s report was an inadmissible net opinion and plaintiff needed to present an expert opinion to establish that the drainage system worsened the conditions of the sidewalk beyond the natural hazards created by the storm, the court found that there was no genuine issue of material fact that could defeat defendants’ summary judgment motion.
Further, the trial court rejected plaintiff’s argument that he could proceed without an expert. Without an expert, it was mere speculation that the drainage system somehow caused the sidewalk conditions.
The plaintiff appealed the summary judgment dismissal to the Appellate Division. Upon appeal, the plaintiff did not argue that the trial court made a mistake in barring his expert. Rather, upon appeal, plaintiff argued that he did not need an expert to be able to argue that the defendants’ drainage system caused water to collect on the sidewalk, which could be a hazard when the weather was cold.
The Appellate Division first noted that residential property owners can be liable “if their actions create an artificial, dangerous condition on an abutting sidewalk, thereby negligently introducing a new element of danger other than one created by natural forces.” Further, the Court noted that “homeowners have no duty to maintain the sidewalks abutting their property so long as they have not affirmatively created a hazardous condition.” Thus, for plaintiffs to overcome defendants’ immunity from sidewalk liability, the plaintiff must present competent evidence showing defendants created or exacerbated a hazardous condition on the sidewalk.
Plaintiff was asserting that the defendants’ drainage system routed precipitation from a prior storm causing it to pool on the sidewalk which then froze to form a sheet of ice. However, the Appellate Division agreed with the trial court that expert testimony would be needed to establish that the cause of the water on the sidewalks was from the defendants’ drainage system.
The Court found that the “topography of defendants’ property, the relative slope and manner in which water drained off the property, and whether the drainage system led to water pooling on the sidewalk under the facts presented here, required an expert’s specialized and technical knowledge to establish defendants’ negligence was the proximate cause of plaintiff’s slip and fall injury.” The Appellate Division ruled that a jury would not be competent “to supply the requisite standard by which to measure defendants’ conduct and would be left to speculate.” Thus, the Court agreed with the trial court that defendant’s negligence could not be established without the aid of an expert and upheld the summary judgment dismissal.
