In 1992, a four-year-old girl in Washington state took one bite of a hamburger from a fast-food chain and became the centerpiece of a legal case that would redefine how courts handle contaminated food. That burger was tainted with E. coli O157:H7, a virulent strain that attacks the lining of the intestines and can shut down the kidneys. The girl survived, but her kidneys were permanently damaged. Her family sued the restaurant chain, and the resulting verdict sent a shockwave through the food industry. This case did not hinge on whether the restaurant intended to serve poison. It did not even require proof that the restaurant was careless. Instead, it rested on a legal principle called strict liability.

Strict liability means that if you sell a product that is defective and that defect causes injury, you are responsible regardless of how careful you were. For food and medicine, this is the sharpest sword a consumer has. You do not need to prove that the factory workers sneezed on the assembly line or that the pharmaceutical company skipped safety tests. You only need to prove three things: the product was defective, the defect existed when it left the seller’s control, and the defect directly caused your injury. In the burger case, the defect was the contamination. The girl did not have to show that the patty was undercooked because the restaurant was in a hurry. She only had to show that the patty made her sick and that it was sold to her in that condition.

This is a fundamentally different approach from negligence, which requires showing that the seller failed to act with reasonable care. Consider a medicine that contains a toxic impurity. Under negligence, you would need to find documents proving that the manufacturer ignored a quality-control report showing the impurity. That is expensive, time-consuming, and often impossible because those documents are locked in corporate legal departments. Under strict liability, you simply show that the pill you bought had the impurity, that the company made the pill, and that you got sick from it. The company may have the world’s best safety record, it may have spent millions on testing, and it may have followed every government regulation to the letter. None of that matters. The defective product itself is enough to impose liability.

Why does the law treat food and medicine this harshly? The reasoning is straightforward. These are products that go inside the human body, often without any realistic way for the consumer to inspect them. You cannot test a hamburger patty for E. coli in your kitchen. You cannot run a chromatography analysis on a prescription capsule before you swallow it. The consumer relies entirely on the manufacturer and the seller to ensure safety. When that trust is broken and the product is dangerous, the seller is in a far better position than the consumer to prevent the contamination, to insure against the risk, and to spread the cost of injuries across all customers through pricing. The law places the burden where it can best be managed.

The real-world stakes of this principle are brutal and immediate. In the early 2000s, a contaminated batch of the blood thinner heparin killed over a hundred patients in the United States. The manufacturer faced lawsuits under strict liability. The victims’ families did not need to prove that the company knew the raw ingredient was tainted with a synthetic oversulfated chondroitin sulfate. They needed only to prove that the heparin they received was defective and caused the deaths. The resulting settlements and verdicts cost the company hundreds of millions of dollars. More importantly, the legal exposure forced the entire pharmaceutical supply chain to demand stricter testing from overseas suppliers.

The same logic applies to a contaminated lettuce recall. If a bag of pre-washed salad greens carries Salmonella, every person who gets sick can sue the grower, the processor, and the grocery store. The grocery store, in turn, can sue the processor, and the processor can sue the grower. This chain of liability is called indemnification, and it ensures that the cost of contamination flows backward to the party most responsible for the defect. The store may have stored the salad at the correct temperature, the processor may have washed it three times, and the grower may have used clean irrigation water. If the contamination is still present, strict liability means someone pays. In practice, the deep pocket at the end of that chain decides it is cheaper to invest in better sanitation and testing than to keep paying judgments.

There are limits to this doctrine. A manufacturer is not liable if the consumer alters the product in a way that causes the harm. If you leave a refrigerated medicine on the dashboard of your car for a week in July and it degrades into a toxic substance, the manufacturer is not liable. The defect must exist at the time the product left the manufacturer’s control. Similarly, if a consumer has an allergic reaction to an ingredient that is clearly listed on the label and is not commonly dangerous to the general population, courts generally will not impose strict liability. The product is not defective simply because it contains an ingredient that some people cannot tolerate.

The takeaway is direct and often uncomfortable for businesses. If you make or sell food or medicine, you are in the business of assuming absolute legal risk for the purity of that product. Good intentions, careful procedures, and perfect safety records will not shield you from liability if a contaminated product goes out the door and into a human body. For the consumer, the message is equally direct. Your legal claim does not rest on proving a mistake. It rests on proving your injury and the defective state of the product. That is the law’s blunt acknowledgment that some risks are so serious and so hard to detect that the cost must be borne by the seller, not the person who takes the bite.