A more thorough explanation:

Alternative liability refers to a situation where two or more parties are responsible for a harm caused to someone, but it is unclear which party caused the harm. In such cases, the burden of proof shifts to each defendant to prove that they did not cause the harm. This type of liability is often seen in product liability cases where multiple manufacturers may have contributed to a defective product.

For example, if a person is injured by a faulty car part, but it is unclear which manufacturer produced the defective part, each manufacturer may be held liable until they can prove that they did not produce the faulty part.