Dependent Intervening Force:
Direct causation is where the defendant’s actions cause the plaintiff’s harm without the assistance of an intervening force. Indirect causation exists when an intervening force comes into play after the defendant has committed his negligent act and this intervening force either extends the plaintiff’s injuries or combines with the defendant’s act to produce plaintiff’s injuries. There are two types of intervening forces to discuss:
- dependent intervening forces and,
- independent intervening forces.
A dependent intervening force is an act of a third person that is considered a normal response to the situation created by the defendant’s negligence. Since such forces arise directly because of the defendant’s negligence they are considered foreseeable and will not relieve the defendant of liability. There are four types of dependent intervening forces:
- checking forces,
- rescue forces,
- escape forces and,
- other response forces.
Checking forces essentially have to do with careless medical treatment that a plaintiff receives as a result of a defendant’s negligence. For example:
Ishmael negligently hits Ahab with his car. Ahab is rushed to the hospital and is sent into surgery. During the course of the operation, the surgeon is careless and causes Ahab more injuries.
In situations like this, the doctor’s carelessness represents a dependent intervening act. However, it is considered foreseeable that a plaintiff would need medical care as a result of a defendant’s negligence. It is also considered foreseeable that the medical care would be administered carelessly. Therefore, the defendant would be liable for both the harm he inflicted on the plaintiff himself and for the harm the plaintiff suffered in the hospital.
Thus, in our example, Ishmael would be liable for both the harm he inflicted on Ahab himself and for the harm Ahab suffered as a result of the doctor’s carelessness.
Please note that this does not apply where medical care was performed recklessly or where medical malpractice was committed deliberately. In such a case, the intervening act is certainly not considered "forseeable". For example:
If the surgeon operated on Ahab while drunk, Ishmael would not be held liable for that.
The second type of dependent intervening force is rescue forces. For example:
Ishmael negligently pushes Ahab into a river. Bartleby sees that Ahab has fallen into the river and attempts to go to Ahab’s aid. Bartleby goes about trying to rescue Ahab as carefully as he can but he accidentally injures Ahab during the rescue attempt anyway. Because “danger invites rescue” it is considered foreseeable that someone would come to Ahab’s aid after Ishmael pushed him into the river. It is also foreseeable that the rescue attempt would cause Ahab further harm. Therefore, Ishmael is liable both for the injuries he caused Ahab directly and for whatever injuries Bartleby might have unintentionally inflicted upon him.
The third kind of dependent intervening force is escape forces. For example:
Ishmael negligently sets a fire in an apartment building. The fire causes a panic and residents rush to try to escape the burning building. In the rush to get out, Ahab is knocked to the ground and trampled by the other residents. According to the law, it is foreseeable that individuals threatened with harm will try to escape. It is also foreseeable that those efforts to escape may endanger others. Therefore, Ishmael is held liable for Ahab’s injuries, even though they were caused by the escaping crowd.
The fourth kind of dependent intervening force is response forces and other reactions by both humans and animals that the law considers foreseeable. For example:
While Ahab is riding a horse, Ishmael fires a gun and startles the horse. The horse rears up and throws Ahab off of its back. If Ahab is injured, Ishmael will be held liable for those injuries since the horse’s reaction to being startled is considered normal and, thus, foreseeable.
Please remember that the most important requirement in all dependent intervening force cases is that the response to the situation created by defendant’s negligence must be considered normal. If the response is unusual or abnormal it is not considered a dependent intervening force and the defendant will not be held liable for the results of those abnormal reactions.
An independent intervening force is one that operates upon the situation created by the defendant’s negligence, but which is not a direct response or reaction to the negligence. Such forces may be acts of third persons or acts of G-d. Where an independent intervening force occurs, the defendant will remain liable for the foreseeable results of his act. See
Ishmael negligently hits Ahab with his car. Ahab, who is severely injured, is taken to the hospital where he is operated on. During the operation, bacteria in the air enters Ahab’s surgical incisions and Ahab suffers a severe infection. Since it is reasonably foreseeable that Ahab’s surgical incisions may become infected, Ishmael will be held liable for the infection.
However, if the force is an intentionally tortious or criminal act, the defendant will not be held liable. This is because, ordinarily, criminal acts on the part of others are not reasonably foreseeable.
If the defendant’s negligence, however, has created a situation in which a reasonable person would have foreseen that negligent, intentional or even criminal acts might be committed by others, then those acts are considered foreseeable intervening forces and they will not excuse defendant from liability. See
Ishmael owns an apartment building in a high crime neighborhood. Ishmael fails to properly install locks on the entrances to the common areas of the building. Ahab is mugged in the lobby of the building. Ishmael may be held liable for Ahab’s injuries because, given the nature of the neighborhood, it is foreseeable that someone could be attacked if the building was not properly secure.
However, where a third person’s criminal or tortious conduct was not reasonably foreseeable and the defendant’s conduct has not enhanced the risk that the criminal action will occur, the defendant may be insulated from liability. For example:
Ishmael, a crew member on a whaling ship, negligently fails to properly seal the fuel tanks on the ship. The result is that the ship’s hull fills with gasoline fumes. Later that day, Ahab, a fire-bug, sets fire to the ship. The fumes are ignited and the ship explodes. Here, Ishmael may be insulated from liability. If he had no reason to expect Ahab’s intentionally tortious or criminal act and Ishmael’s negligence did not give rise to the act or enhance the risk that such an act would occur, he is not liable even though the resulting harm was foreseeable.
The rationale for this is that the guilt of the criminal whose misconduct was intentional or reckless overwhelms the responsibility of the defendant who was merely negligent.
Please note that we are talking here about unforeseeable criminal or tortious acts. A third person’s negligent conduct, even it was unforeseeable, does not relieve the defendant of liability if it causes a result similar to that threatened by the defendant’s conduct. Only intentionally tortious or criminal actions will relieve the defendant of liability. For example:
Ishmael negligently builds a brick wall. The wall falls down injuring Ahab, but only after Bartleby has crashed into the wall with his car. In this case, Ishmael will be held liable for Ahab’s injuries because the wall’s falling and injuring Ahab, a passerby, is a foreseeable result of Ishmael’s original negligence. The fact that the wall falling was brought about by Bartleby’s negligent driving will not insulate Ishmael from liability.
However, if the third person’s negligence was highly extraordinary under the circumstances (in other words more than just unforeseeable) then the defendant will be insulated from liability.
In a situation where a defendant commits an act of negligence that injures a plaintiff and a third person is in a position to save the plaintiff but does nothing, the third person’s failure to prevent the harm is not considered an intervening act. Therefore, the failure of a third person to act does not insulate the defendant from liability even if the third person is under a legal duty to act. For example:
- Ishmael pushes Ahab into a swimming pool. Ahab begins to drown. Bartleby, another swimmer, is in a position to save Ahab but does nothing. Even though Bartleby could have saved Ahab from the harm he suffered, Ishmael will still be held liable for Ahab’s injuries.
- Ishmael negligently pushes Ahab into a swimming pool. Ahab begins to drown. Bartleby, a lifeguard, is in a position and under a legal obligation to go to Ahab’s rescue but does nothing. Although Bartleby was in a position to save Ahab and although Bartleby had a legal obligation to go to Ahab’s rescue, Ishmael will nevertheless be held liable for Ahab's injuries.
As far as unforeseeable results produced by foreseeable intervening forces are concerned, there is essentially a split in the authorities. Even though the intervening force may be foreseeable, some courts will not hold the defendant liable if the result was unforeseeable. However, other courts will nevertheless impose liability.
If, however, both the intervening forces and their results are unforeseeable, all courts hold that the defendant is not liable.