A manufacturer may be liable when a product does not cause the initial accident but is defectively designed so that it makes the resulting injuries worse than they should have been.

Most often seen in vehicle cases, the idea applies more broadly to products that should protect people during a foreseeable impact, rollover, collapse, or other dangerous event. A car with a roof that caves in too easily, a seatback that fails in a rear-end crash, or a fuel system that turns a survivable collision into a fire are common examples. The focus is not on who caused the first event, but on whether a safer design could have reduced the harm. That often leads to questions about design defect, causation, and how experts separate the original injury from the added injury caused by the product's failure.

For an injury claim, the doctrine can make a major difference because it can open the door to a product liability case even when another driver or worker triggered the accident. In Connecticut, these claims are generally brought under the Connecticut Product Liability Act, Conn. Gen. Stat. §§ 52-572m to 52-572r. Damages may include the extra medical treatment, disability, pain, and loss tied to the enhanced injuries, and Connecticut does not cap non-economic damages in personal injury cases. In severe trauma cases, treatment records from facilities such as Yale-New Haven Hospital can become key evidence in showing how much worse the injuries became.