A breach of duty occurs when a party fails to carry out the functions of his or her office or position. In the U.S., this mainly applies to corporate officers, fiduciary agents and/or those in the various financial industries. Breach of duty is an important element of litigation when it comes to proving negligence.
In determining whether or not a breach of duty occurred, the court must decide if the defendant's behavior was reasonable under the circumstances. In the case of asbestos litigation, the question is whether or not the company was aware of the toxicity of the substance, and if so, how a reasonable and responsible person would have acted in a supervisory position.
Once determined, the standard of care can help the court in deciding if the defendant was indeed negligent. In order to prove negligence, the plaintiff must prove to the court that the defendant had indeed recognized the risks of a particular activity or substance, and understood the consequences of those risks. This standard of care is then applied to the specific elements of the case at hand in order for the jury to establish negligence on the part of the plaintiff.
In some cases, the standards of reasonable care are determined by statute, meaning that the court is relieved of the responsibility of interpreting the standards. In this case, a breach of duty would be a violation of the law.
If the plaintiff cannot provide tangible evidence that a defendant was negligent because such evidence is not accessible, s/he can resort to res ipsa loquitur (rehss IH-psah LAW-kwih-toor), which literally means "the thing itself speaks," or "the act speaks for itself." In an asbestos case, one's own illness provides the evidence of injury. However, the plaintiff must still prove that the exposure was due to negligence on the part of the defendant, and that the defendant had knowledge of and control over its effects (i.e., might have issued warnings and provided protective equipment).