Copyright 1965, American Law Institute

Division One - Intentional Harms to Persons, Land, and Chattels
Chapter 1 - Meaning of Terms Used Throughout the Restatement of Torts

§ 4 DUTY

 The word "duty" is used throughout the Restatement of this Subject to denote the fact that the actor is required to conduct himself in a particular manner at the risk that if he does not do so he becomes subject to liability to another to whom the duty is owed for any injury sustained by such other, of which that actor's conduct is a legal cause.


a.  The duty which is defined in this Section is a duty that the actor shall conduct himself or not conduct himself in a particular manner. It therefore imposes no obligation which is not within the actor's ability to perform, since it relates only to the actor's conduct over which as such he has control. It is in this sense that the word "duty" is used throughout the Restatement of this Subject. The breach of a duty, as the word is used in the Restatement of this Subject, does not make the actor liable. It merely subjects him to liability. (See § 5.) Whether he is liable or not depends on matters which are usually beyond his control. Thus, whether or not he is liable depends upon whether his breach of duty results in an injury to someone to whom the duty is owing in such a manner as to make the breach of the duty a legal cause of the injury, and this depends upon the course of events subsequent to the actor's breach of his duty, a matter over which the actor has no effective control; and upon the further condition that the other has not been guilty of fault contributing to his injury, a matter which is within the sole control of the other. One who digs a ditch in a public highway is under a duty to set lights around it as night approaches so as to give travelers warning of its existence. His failure to set lights is a breach of his duty, but this of itself is not enough to make him liable. He does not become liable unless and until some traveler, himself paying due attention to his path, and thus excusably ignorant of the ditch the existence of which the lights would have disclosed, falls into it and is injured.

b.  Most common use of "duty."  The word "duty" is used most frequently in that part of the Restatement of this Subject which deals with the subject of Negligence. This usage conforms to that of courts in dealing with negligence problems. It is particularly valuable in describing the requirement that action shall be taken for the protection of the interests of others. It is also useful to describe the requirement that the actor, if he acts at all, must exercise reasonable care to make his acts safe for others. "Duty" is rarely used in dealing with the invasions of legally protected interests by acts which are intended to invade them. In the sense in which it is defined in this Section, it is not, and cannot be, used in dealing with the liability which is the legal consequence of conduct which is at the peril of the actor. The keeping of wild and ferocious domestic animals and the carrying on of abnormally dangerous activities, such as blasting or the like, are the typical situations in which the actor's conduct is at the peril of answering for harm caused by it, even though the utmost care is exercised in the keeping of the animal or the conduct of the activity. In none of these is the conduct of the actor morally or socially improper. Its social utility or its traditional character is sufficient to prevent the existence of any duty to refrain from it, and thus prevents it from being negligent as involving an unreasonable risk of harm. The liability in such situations is often called liability without fault, and the words "without fault" preclude the idea that the conduct is a breach of a duty to refrain from it. In a word, there is liability without breach of any antecedent duty. Such a duty as there is, is merely a duty to make reparation for the other's injury, a duty which is implicit in the words "liable" and "liability." This type of duty exists equally where the breach of an antecedent duty to exercise care is the legal cause of harm to an interest protected against negligence.

c.  "Duty," as the word is used in all the Subjects of the Restatement, is a duty to conduct one's self in a particular manner. While in this fundamental particular the duty in tort is identical with that in contract, there are certain particulars in which the duty in contract differs from that in tort, and which entail differences in the effect of the breach of the duty in creating liability. The duty in contract is normally to do or refrain from doing a particular or definite thing irrespective of the end which is to be served. The purpose of the contract duty is to secure the receipt of the thing bargained for. The breach of the contract prevents this from being obtained, and the harm which the performance of the duty would have prevented has occurred. There is, therefore, liability even if only for nominal damages. On the other hand, the duty in tort is only occasionally to do or refrain from doing a particular thing, and even then the doing or non-doing of the thing is not the end or the purpose of the duty itself. It is merely a means whereby the interest protected by the duty can be made secure. Therefore, the harm which the duty is intended to prevent does not occur until the interest protected by it is invaded and, therefore, until such invasion occurs there can be no liability for the breach. In addition, the actor's duty in tort is often to conduct himself in a manner the propriety of which is to be determined ex post facto by the jury in their determination as to whether the actor has or has not used reasonable care.