Products Liability Law Daily Wrap Up, DESIGN AND MANUFACTURING DEFECTS—HOUSEHOLD PRODUCTS—1st Cir.: Summary judgment in favor of fan makers upheld in insurer’s fire-loss case, (Sep 2, 2026)

By Pankhuri Bhatnagar, B.A. LL.B.

The insurer’s malfunction theory could not overcome its failure to distinguish a manufacturing defect from a design defect or establish a reasonable alternative design.

In an action brought against the manufacturers of an exhaust fan and its motor by an insurer as subrogee of a homeowner whose residence was damaged by a bathroom-fan fire, the U.S. Court of Appeals for the First Circuit affirmed summary judgment for the manufacturers. The appeals court held that the insurer did not challenge the exclusion of its expert’s undisclosed opinions, failed to preserve its malfunction theory argument as to design defect, and lacked sufficient evidence to show that the fan or motor deviated from its intended design or that a specific manufacturing defect caused the fire (Citation Insurance Co. v. Broan-NuTone LLC, No. 25-1426 (1st Cir. Aug. 28, 2026)).

Background. In September 2020, a man called a technician to upgrade his home’s WiFi system. After the technician reported that a fuse on the basement circuit breaker had tripped, smoke detectors sounded upstairs, and the homeowner discovered heavy smoke and fire near the attic stairway. The Burlington Fire Department determined that the fire originated from a bathroom vent fan and had no connection with the technician’s work. The homeowner received $726,379 for the loss of his real and personal property from his insurer, Citation Insurance Company. The insurer then brought a subrogee suit against the exhaust fan’s manufacturer, Broan-NuTone LLC, and the fan motor’s manufacturer, Jakel Motors Incorporated (together, manufacturers or companies). Notably, the fan had a thermal cut off (TCO) device which was designed to melt open when the motor reached an unacceptable temperature and cut power before overheating could cause a fire. The complaint asserted manufacturing defect and design defect theories sounding in both breach of implied warranty and negligence.

Prior proceedings. The companies moved for summary judgment based on the insurer’s delayed expert testimony and lack of factual allegations. Citation relied on its fire analyst who concluded that the fire originated at the fan and found no other competent ignition source, and an electrical engineer, who concluded that the motor coil’s electrical arcing (caused by deficiencies in the fan’s design and manufacture) led to the fire. A district court found that the engineer’s deposition introduced three matters that his expert report had not clearly disclosed: a specific manufacturing defect, how that defect caused the fire, and potential alternative designs and their feasibility. Because Rule 26(a)(2)(B)(i) requires an expert report to contain a complete statement of the opinions the witness will express and their bases and reasons, the court excluded those portions and held that summary judgment was warranted for the manufacturers after the exclusion of that expert testimony. The insurer appealed.

Design defect. A design defect requires a foreseeable risk that could have been reduced or avoided through a reasonable alternative design. Evans v. Lorillard Tobacco Co., 990 N.E.2d 997, 1011, 1015 (Mass. 2013). Citation argued that the malfunction theory allowed circumstantial proof of a design defect without identifying how the product was designed or manufactured. The manufacturers disputed whether Massachusetts recognized that theory and whether it applied where no expert established that destruction of the product prevented identification of the defect. The court declined to resolve those questions because Citation had not relied on the malfunction theory below to establish a design defect. Instead, it had argued in the district court that the engineer’s deposition supplied sufficient evidence of reasonable alternative designs to create a genuine dispute as to a design defect. On appeal, the insurer did not challenge the exclusion of its expert’s testimony or identify other evidence establishing reasonable alternative designs. Because it raised its malfunction theory as a design-defect basis for the first time on appeal, the new argument could not be considered as per Morales Feliciano v. Rullan, 378 F.3d 42, 49 (1st Cir. 2004), and judgment was upheld on the design defect-based warranty theory.

Manufacturing defect. A manufacturing defect occurs when a product deviates from its intended design because of a manufacturing error. Back v. Wickes Corp., 378 N.E.2d 964, 970 (Mass. 1978). Citation argued that it had preserved its malfunction theory as to a manufacturing defect and had shown that the fan caused the fire even without identifying the precise failure within the thermal cutoff device. It pointed to three potential TCO deficiencies identified in its opposition motion: the device’s 90-degree Celsius rating and possible degradation at higher temperatures, its ability to continue conducting electricity after its fusible element melted, and improper bending of its lead wire that could cause a fire. But those circumstances did not permit a factfinder to determine that the TCO contained a manufacturing defect rather than a design defect. For instance, nothing showed that its temperature rating deviated from identical products issued by the same manufacturer or that such a defect occurs due to a manufacturing error. The engineer himself testified that he did not know why the TCO failed, only that it had failed. Accordingly, a factfinder could not compare the propensities of the device with those it was intended to have, and summary judgment was affirmed on this theory as well.

Invited error. The First Circuit acknowledged that the result might appear unusual because the malfunction theory arguably permits a plaintiff to establish a defect without identifying its precise nature. But Citation had structured its district-court case differently: it relied on alternative-design evidence for design defect and invoked malfunction theory only to establish manufacturing defect. That litigation strategy left Citation unable to demonstrate the particular inference necessary for a manufacturing defect and unable to introduce the design-defect argument it had not preserved below. A party generally may not complain on appeal about an error it invited through its own litigation choices. Orenstein v. United States, 191 F.2d 184, 193 (1st Cir. 1951). Accordingly, the insurer was bound by the consequences of its approach and the lower court’s judgment was affirmed on all claims.

The case is No. 25-1426.

Judge: Barron, D.

Attorneys: Katherine Cleary Loftus (Loftus & Loftus PC) for Citation Insurance Co. Andrew D. Black (Smith Duggan Cornell & Gollub LLP) for Broan-Nutone LLC.

Companies: Citation Insurance Co.; Broan-Nutone LLC

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