In assessing proximate causation, what is the relationship between foreseeability, direct causation, and indirect causation?

When determining if a defendant should be held responsible (liable) for harm, the law looks at whether the harm was foreseeable and whether the defendant's actions directly or indirectly caused the harm.

If the defendant’s actions are the direct cause of the harm, this means there is a straight line between what the defendant did and the injury that occurred. In this case, the defendant is responsible for all foreseeable harmful outcomes—those results that a reasonable person could predict might happen because of the defendant’s actions. For example, if a driver runs a red light and hits a pedestrian, the injury to the pedestrian is a foreseeable result of running the light. However, the defendant won’t be held responsible for unforeseeable results, like a totally random event outside the risks created by their actions (such as lightning striking the pedestrian at the exact same moment).

In situations of indirect causation, where something happens between the defendant’s actions and the harm (called an intervening cause), the defendant can still be held liable, but only if both the result and the intervening cause were foreseeable. For instance, if someone’s negligence causes a fire, and a firefighter is injured while putting out the fire, the defendant may be responsible because it is foreseeable that firefighters would respond to a fire, and injuries in such situations are also foreseeable. But, if something truly unusual or unexpected happens (like a wild animal escaping from the zoo because of the fire and causing harm), the defendant may not be held responsible because neither the wild animal's escape nor the harm caused by it was foreseeable.