A plaintiff in a Massachusetts personal injury action, in addition to showing a duty and a breach of that duty, must also establish causation, which includes both factual causation and legal causation. To establish factual causation, a plaintiff needs to show that there is a greater likelihood that the alleged harm was due to causes that the defendant was responsible for rather than from any other cause. Factual causation is usually proved under Massachusetts law by using a “but for” test, which means proving that but for the defendant’s conduct, the injury or harm would not have occurred. A plaintiff is not required, however, to eliminate all possibility that the defendant’s conduct was not a cause of his or her personal injuries in order to prevail in a Massachusetts tort action.
To establish legal cause, which is also called proximate cause, the Massachusetts accident victim must show that it is more likely than not that the defendant’s conduct was a substantial and contributing cause to the accident and to the injuries that occurred as a result. To establish legal causation, it is necessary only to show that the defendant took a risk involving the plaintiff’s safety that a reasonable person would not have taken, and that as a result, the plaintiff sustained injuries that were foreseeable.
Even when causation is established, if a superseding intervening cause exists, the defendant will not be held liable. A superseding intervening cause is an act of a third person or other force that breaks the chain of causation between the defendant’s conduct and the plaintiff’s injuries. For example, the act of committing suicide is a supervening intervening cause that will prevent the defendant from being held liable for money damages arising out of the suicide.
