If the new event, whether through human agency or natural causes, does not break the chain, the original actor is liable for all the consequences flowing naturally from the initial circumstances. But if the new act breaks the chain, the liability of the initial actor stops at that point, and the new actor, if human, will be liable for all that flows from his or her contribution.
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something that happens between the first event in a sequence and the end result, and in so doing changes the natural course of events that might have connected a wrongful act to an injury or loss.
The intervening cause breaks the chain of causation between the defendant and claimant.