Copyright 1965, American Law Institute

Division Two - Negligence
Chapter 12 - General Principles
Topic 2 - The Standard By Which Negligence is Determined


 Unless the actor is a child, the standard of conduct to which he must conform to avoid being negligent is that of a reasonable man under like circumstances.


a.  This Section is concerned only with the standard of conduct required of the actor to avoid being negligent. It is not concerned with the question of when he owes to another a duty to conform to that standard.

b.  Qualities of the "reasonable man."  The words "reasonable man" denote a person exercising those qualities of attention, knowledge, intelligence, and judgment which society requires of its members for the protection of their own interests and the interests of others. It enables those who are to determine whether the actor's conduct is such as to subject him to liability for harm caused thereby, to express their judgment in terms of the conduct of a human being. The fact that this judgment is personified in a "man" calls attention to the necessity of taking into account the fallibility of human beings.

c.  Standard of the "reasonable man."  Negligence is a departure from a standard of conduct demanded by the community for the protection of others against unreasonable risk. The standard which the community demands must be an objective and external one, rather than that of the individual judgment, good or bad, of the particular individual. It must be the same for all persons, since the law can have no favorites; and yet allowance must be made for some of the differences between individuals, the risk apparent to the actor, his capacity to meet it, and the circumstances under which he must act.

In dealing with this problem the law has made use of the standard of a hypothetical "reasonable man." Sometimes this person is called a reasonable man of ordinary prudence, or an ordinarily prudent man, or a man of average prudence, or a man of reasonable sense exercising ordinary care. It is evident that all such phrases are intended to mean very much the same thing. The actor is required to do what this ideal individual would do in his place. The reasonable man is a fictitious person, who is never negligent, and whose conduct is always up to standard. He is not to be identified with any real person; and in particular he is not to be identified with the members of the jury, individually or collectively. It is therefore error to instruct the jury that the conduct of a reasonable man is to be determined by what they would themselves have done.

The chief advantage of this standard of the reasonable man is that it enables the triers of fact who are to decide whether the actor's conduct is such as to subject him to liability for negligence, to look to a community standard rather than an individual one, and at the same time to express their judgment of what that standard is in terms of the conduct of a human being. The standard provides sufficient flexibility, and leeway, to permit due allowance to be made for such differences between individuals as the law permits to be taken into account, and for all of the particular circumstances of the case which may reasonably affect the conduct required, and at the same time affords a formula by which, so far as possible, a uniform standard may be maintained.

d.  The qualities of a reasonable man which are of importance differ with the various situations in which the phrase is used. In determining whether the actor should realize the risk which his conduct involves, the qualities which are of importance are those which are necessary for the perception of the circumstances existing at the time of his act or omission and such intelligence, knowledge, and experience as are necessary to enable him to recognize the chance of harm to others involved therein. (See §§ 289 and 290.)

e.  Weighing interests.  The judgment which is necessary to decide whether the risk so realized is unreasonable, is that which is necessary to determine whether the magnitude of the risk outweighs the value which the law attaches to the conduct which involves it. This requires not only that the actor give to the respective interests concerned the value which the law attaches to them, but also that he give an impartial consideration to the harm likely to be done the interests of the other as compared with the advantages likely to accrue to his own interests, free from the natural tendency of the actor, as a party concerned, to prefer his own interests to those of others.

f.  Reasonable consideration for others and reasonable prudence.  In so far as the conduct of the reasonable man furnishes a standard by which negligence is to be determined, the standard is one which is fixed for the protection of persons other than the defendant. In so far as the contributory negligence of the actor is concerned, the standard is one to which the actor is required to conform for his own protection (see § 463). When a plaintiff's contributory negligence is in question, the "reasonable man" is a man of reasonable "prudence." Where a defendant's negligence is to be determined, the "reasonable man" is a man who is reasonably "considerate" of the safety of others and does not look primarily to his own advantage.

REPORTERS NOTES:  The "reasonable man" is first mentioned in Vaughan v. Menlove, 3 Bing. N.C. 468, 132 Eng. Rep. 490 (1837). See also Blyth v. Birmingham Waterworks Co., 11 Ex. 781, 784, 156 Eng. Rep. 1047 (1856), "reasonable man"; Drown v. New England Tel. & Tel. Co., 81 Vt. 358, 70 A. 599 (1908), "prudent man"; Davis v. Concord & Montreal R. Co., 68 N.H. 247, 44 A. 388 (1894), "man of average prudence"; Osborne v. Montgomery, 203 Wis. 223, 234 N.W. 372 (1931), "ordinarily prudent man"; Warrington v. New York Power & Light Corp., 252 App. Div. 364, 300 N.Y.S. 154 (1937), "typical prudent man"; Charbonneau v. MacRury, 84 N.H. 501, 153 A. 457, 73 A.L.R. 1266 (1931), "average person of ordinary prudence."

An amusing, and very accurate description of the "reasonable man" as a person is found in Herbert, Uncommon Law 1-6 (7th ed. 1952).

It is error to instruct the jury that the actor was not negligent if he used his own best judgment. The Germanic, 196 U.S. 589, 25 S. Ct. 317, 49 L. Ed. 610 (1905); Maguire v. Barrett, 223 N.Y. 49, 119 N.E. 79 (1918); Beahan v. St. Louis Public Service Co., 361 Mo. 807, 237 S.W.2d 105 (1951); Mertz v. Connecticut Co., 217 N.Y. 475, 112 N.E. 166 (1916); and cf. Hover v. Barkhoof, 44 N.Y. 113 (1870).

It is error to instruct the jury that the actor must have used such care as they themselves would have used. Louisville & N. R. Co. v. Gower, 85 Tenn. 465, 3 S.W. 824 (1887); Freeman v. Adams, 63 Cal. App. 225, 218 P. 600 (1923); Warrington v. New York Power & Light Corp., 252 App. Div. 364, 300 N.Y.S. 154 (1937).

See Allen, Learned and Unlearned Reason, 36 Jurid. Rev. 254 (1924); Bohlen, Mixed Questions of Law and Fact, 72 U. Pa. L. Rev. 111, 113 (1924); Seavey, Negligence -- Subjective or Objective, 41 Harv. L. Rev. 1, 27 (1927); Green, The Negligence Issue, 37 Yale L.J. 1029 (1928), in Judge and Jury 153, 166 (1930); James, The Qualities of the Reasonable Man in Negligence Cases, 16 Mo. L. Rev. 1 (1951).