Civil Jury Instructions Home

3.1-5  Proximate Cause - Multiple Causes

Revised to January 1, 2008

Under the definitions I have given you, negligent conduct can be a proximate cause of an injury if it is not the only cause, or even the most significant cause of the injury, provided it contributes materially to the production of the injury, and thus is a substantial factor in bringing it about.  Therefore, when a defendant's negligence combines together with one or more other causes to produce an injury, such negligence is a proximate cause of the injury if its contribution to the production of the injury, in comparison to all other causes, is material or substantial. 

When, however, some other (cause / causes) contribute[s] so powerfully to the production of an injury as to make the defendant's negligent contribution to the injury merely trivial or inconsequential, the defendant's negligence must be rejected as a proximate cause of the injury, for it has not been a substantial factor in bringing the injury about. 

<Instruct jurors as to how the foregoing principles apply to the facts and issues of the case on trial.>

Authority

Boileau v. Williams, 121 Conn. 432, 440 (1936) ("[A] defendant's negligence, to impose liability, must have been a proximate and substantial cause of the injury. . . .  [I]f the negligence of one only of the defendants caused the collision [which produced the injury,] that defendant only would be liable, but if the negligence of both contributed in a proximate and material way to cause it, both should be held liable. . . .  When . . . injuries are claimed to have been caused by the concurring negligence of two defendants, and it is claimed that the active operation of the negligence of one is such a supervening cause as to prevent the antecedent negligence of the other from being a substantial factor in producing the injury, a statement to the jury of the general rule without any direction as to its application to the particular facts of the case will not ordinarily be sufficient to enable a jury of laymen to understand and correctly apply rules which eminent jurists and text-writers have found no little difficulty in expounding."); Mahoney v. Beatman, 110 Conn. 184, 197 (1929) ("Whether an injury following a negligent act is caused by this act depends upon whether it is traceable in causal relation to the tortious act. Or, expressed in another form, was this act a substantial factor in causing this later injury?").

See also 2 Restatement (Second), Torts § 439 ("If the effects of the actor's negligent conduct actively and continuously operate to bring about harm to another, the fact that the active and substantially simultaneous operation of the effects of a third person's innocent, tortious, or criminal act is also a substantial factor in bringing about the harm does not protect the actor from liability").

Notes

The term "supervening cause" is not used in this instruction because it appears rarely in our case law and risks confusing the jury on the related but quite different subject of "superseding cause."  A "supervening cause" is one whose contribution to the production of an injury is so powerful as to make the defendant's negligent contribution to the injury merely trivial or inconsequential, and thus not a substantial factor in producing the injury.

A superseding cause, by contrast, is any force which, by its intervention in the sequence of events leading from the defendant's negligence to the plaintiff's injury, prevents the defendant from being held liable for the injury even though (his/her) negligence has been a substantial factor in bringing the injury about.