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The reasonable person is a legal fiction of the common law representing an objective standard against which any individual's conduct can be measured. It is used to determine if a breach of the standard of care has occurred, provided a duty of care can be proven.

The reasonable person standard holds: each person owes a duty to behave as a reasonable person would under the same or similar circumstances. While the specific circumstances of each case will require varying kinds of conduct and degrees of care, the reasonable person standard undergoes no variation itself.

This standard performs a crucial role in determining negligence in both criminal law—that is, criminal negligence—and tort law. The standard also has a presence in contract law, though its use there is substantially different.

The standard does not exist independently of other circumstances within a case which could affect an individual's judgment.


The first appearance of the reasonable person standard was in the English case of Vaughan v. Menlove (1837). In Menlove, the defendant had stacked hay on his rental property in a manner prone to spontaneous ignition. After repeated warnings over the course of five weeks, the hay ignited and burned the defendant's barns and stable, and then spread to the landlord's two cottages on the adjacent property. Menlove's attorney admitted his client's "misfortune of not possessing the highest order of intelligence," arguing that negligence should only be found if the jury decided Menlove had not acted with "bona fide [and] to the best of his [own] judgment."

The Menlove court disagreed, reasoning that such a standard would be too subjective, instead preferring to set an objective standard by which to adjudicate cases:

English courts upheld the standard again nearly 20 years later in Blyth v. Company Proprietors of the Birmingham Water Works, holding:


Americanmarker jurist Oliver Wendell Holmes, Jr. explained the theory behind the reasonable person standard as stemming from the impossibility of "measuring a man's powers and limitations." Individual, personal quirks inadvertently injuring the persons or property of others are no less damaging than intentional acts. In order for society to function, "a certain average of conduct, a sacrifice of individual peculiarities going beyond a certain point, is necessary to the general welfare." Thus, a reasonable application of the law is sought, compatible with planning, working, or getting along with others. As such, "his neighbors accordingly require him, at his proper peril, to come up to their standard, and the courts which they establish decline to take his personal equation into account."

The reasonable person standard is by no means democratic in its scope; it is, contrary to popular conception, intentionally distinct from that of the "average person," who is not necessarily guaranteed to always be reasonable. The reasonable person will weigh all of the following factors before acting:
  • the foreseeable risk of harm his actions create versus the utility of his actions;
  • the extent of the risk so created;
  • the likelihood such risk will actually cause harm to others;
  • any alternatives of lesser risk, and the costs of those alternatives.
Taking such actions requires the reasonable person to be appropriately informed, capable, aware of the law, and fair-minded. Such a person might do something extraordinary in certain circumstances, but whatever that person does or thinks, it is always reasonable.

The reasonable person has been called an "excellent but odious character."

English legal scholar Percy Henry Winfield summarized much of the literature by observing that:

Hand Rule

Under American common law, a well known—though nonbinding—test for determining how a reasonable person might weigh the criteria listed above was set down in United States v. Carroll Towing Co. by the Chief Justice of the Second Circuit Court, Learned Hand. The case concerned a barge that had broken her mooring with the dock. Writing for the court, Hand held:

While the test offered by Hand does not encompass all of the criteria available above, juries in a negligence case might well still be instructed to take the other factors into consideration in order to determine whether the defendant was negligent.

Personal circumstances

While the legal fiction of the reasonable person represents the ideal human actor, one would be hard pressed to characterize any individual human as meeting the standard, whether in whole or in part, all of the time. Since some human actors have limitations, the standard only requires that people act similarly to how "a reasonable person under the circumstance" would, as if their limitations were themselves circumstances. As such, courts require that the reasonable person be viewed as experiencing the same limitations as the defendant.

For example, the standard to which a disabled defendant would be held is by necessity how a reasonable person with that same disability would act. One should not mistake this allowance for physical limitations as an allowance for poor judgment, attempting acts beyond one's abilities, or acting too quickly, etc. Were such allowances made for every defendant, there would be as many different standards for negligence as there were defendants; and courts would spend innumerable hours, and the parties much more money, on determining that particular defendant's reasonableness, character, and intelligence.

By using the reasonable person standard, the courts instead use an objective tool and avoid such subjective evaluations. The result is a standard which allows the law to behave in a uniform, foreseeable, and neutral manner when attempting to determine liability.


One broad allowance made to the reasonable person standard is for children. The standard here requires that a child act in a similar manner to how a "reasonable person of like age, intelligence, and experience under like circumstances" would act. In many common law systems, children under the age of 6 or 7 are typically exempt from any liability, whether civil or criminal, as they are deemed to be unable to understand the risk involved in their actions. Children of ages 7 to 17 are held to a reasonable person standard which factors in the criteria above. Although these allowances are made for children, they can still act, and are sometimes found to have acted, in a negligent manner.

One of the exceptions to these allowances concern children engaged in what is primarily considered to be high-risk adult activity, such as operating a motor vehicle.

Mentally ill

The reasonable person standard makes no allowance for the mentally ill. Such a refusal goes back to the standard set in Menlove, where Menlove's attorney argued for the subjective standard. In the 170 years since, the law has kept to the legal judgment of having only the single, objective standard. Such judicial adherence sends a message that the mentally ill would do better to refrain from taking risk-creating actions, unless they exercise a heightened degree of self-restraint and precaution, if they intend to avoid liability.


In cases where a human actor is a professional and is acting within her professional capacity, the "reasonable person under the circumstances" test becomes elevated to a standard of whether the person acted how a "reasonable professional under the circumstances" would have, regardless of whether they are actually a professional or not. Other factors also become relevant, such as the degree to which the professional is educated (i.e., whether a specialist within the specific field, or just a general practitioner of the trade), and customary practices and general procedures of similar professionals.

However, such other relevant factors are never dispositive. Some professions may maintain a custom or practice long after a better method has become available. The new practices, though less risky, may be entirely ignored. In such cases, the practitioner may very well have acted unreasonably despite following custom or general practices.

Medical professionals

In the realm of healthcare, plaintiffs must prove via expert testimony the standard of medical care owed and a departure from that standard. The only exception to the requirement of expert testimony is where the departure from accepted medical practices was so egregious that a layperson can readily recognize the departure.

However, controversial medical practices can be deemed reasonable when followed by a respected and reputable minority of the medical field, or where the medical profession cannot agree over which practices are best.


When any person undertakes a skills-based activity which creates a risk to others, they are held to the minimum standard of how a reasonable person experienced in that task would act, regardless of their actual level of experience.

External circumstances

Factors external to the defendant are always relevant. Additionally, so is the context within which each action is made. It is within these circumstances that the determinations and actions of the defendant are to be judged. There are myriad factors that could provide inputs into how a person acts: individual perceptions, knowledge, the weather, etc. The standard of care required for each set of circumstances will vary, yet the level of care due is always what is reasonable for that set of circumstances.

While community customs may be relied upon to indicate what kind of action is expected in light of given circumstances, such customary requirements are not themselves conclusive of what a reasonable person would do.

It is precisely for this wide-ranging variety of possible facts that the reasonable person standard is so broad (and often confusing and difficult to apply). Although, a few general areas of relevant circumstances rise above the others.

Emergency doctrine

Allowing for circumstances under which a person must act urgently is important to preventing hindsight bias from affecting the trier of fact. Given pressing circumstances, a reasonable person may not always act in a manner similar to how she would have acted in a more relaxed setting. As such, it is only fair that actions be judged in light of any exigent conditions which could have affected how the defendant acted.

Available resources

In certain circumstances, human actors are faced with the problem of making do only with what is available. Such circumstances are relevant to any determination of whether the defendant acted reasonably. Where necessary resources are scarce, certain actions may be reasonable that would be unreasonable if those same resources were available but not readily at hand.

Negligence per se

Because a reasonable person is objectively presumed to know the law, noncompliance with a local safety statute may also constitute negligence. The related doctrine of negligence per se addresses the circumstances under which the law of negligence can become an implied cause of action for breaching a statutory standard of care. Conversely, minimal compliance with a safety statute does not always absolve a defendant if the trier of fact determines that the reasonable person should have taken actions beyond and in excess of what the statute required. However, if the trier of fact finds the statute's standard itself is reasonable and the defendant acted in accordance with what the statute contemplated, the duty of care can be deemed met.

Reasonable bystander

For common law contracts, disputes over contract formation are subjected to what is known as the objective test of assent in order to determine whether a contract exists. This standard is also known as the reasonable bystander, reasonable third party, or reasonable person in the position of the party. This is in contrast to the subjective test employed in most civil law jurisdictions. The test stems from attempts to balance the competing interests of the judicial policies of assent and of reliability. The former holds that no person ought to be contractually obligated if they did not consent to such an agreement; the latter holds that if no person can rely on actions or words demonstrating consent, then the whole system of commercial exchange will ultimately collapse.

Prior to the 19th century, courts used a test of subjective evalutation; that is, the trier of fact determined each party's understanding. If both parties were of the same mind and understanding on matters, then assent was manifested and the contract was valid. Between the 19th and 20th centuries, the courts shifted toward the objectivist test, reasoning that subjective testimony was often unreliable and self-serving.

From those opposite principles, modern law has found its way to a rough middle ground, though it still shows a strong bias toward the objective test. Promises and agreements are reached through manifestations of consent, and parties are liable for actions that deliberately manifest such consent; however, evidence of either party's state of mind can be used to determine the context of the manifestation if said evidence is reliable and compatible with the manifestation in question, though such evidence is typically given very little weight.

Another circumstance where the reasonable bystander test is used occurs when one party has inadvertently misstated the terms of the contract, and the other party sues to enforce those terms: if it would have been clear to a reasonable bystander that a mistake had been made, then the contract is voidable by the party who made the error; otherwise, the contact is binding.

Reasonable woman

Sexual harassment

A variant of the reasonable person can be found in sexual harassment law as the reasonable woman standard. The variation recognizes a difference between men and women regarding the effect of unwanted interaction with a sexual tone. As women have historically been more vulnerable to rape and sex-related violence than have men, courts believe that the proper perspective for evaluating a claim of sexual harassment is that of the reasonable woman.


Though the use of the reasonable woman standard has gained traction in some areas of the law, the standard has not escaped the crosshairs of humorists. In 1927, legal humorist A. P. Herbert considered the concept of the reasonable man at length in the fictional case of "Fardell v. Potts." In Herbert's fictional account, the judge addressed the lack of a reasonable woman standard in the common law, and ultimately concluded that "a reasonable woman does not exist."

Equivalents outside of common law systems

In Roman law, the standard of reasonable care, for example by a trustee or guardian, was that of the paterfamilias. In French law, this is rendered as the bon père de famille, an expression also used in Quebec until it was superseded by the common-law influenced personne raisonnable.




  1. Franklin, at 54
  2. Franklin, at 55
  3. Holmes, at 108.
  4. Herbert, at 12.
  5. Glannon, at pg. 74.
  6. Restatement of the Law, Second, Torts. §283A
  7. Restatement of the Law, Second, Torts. §296
  8. Restatement of the Law, Second, Torts. §288C
  9. Blum, at pg. 53.
  10. Blum, at pg. 52.
  11. Blum, at pg. 54.

See also

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