The
legal fiction This is no excuse for poor judgment, or trying to act beyond one's abilities. Were it so, there would be as many standards as there were defendants; and courts would spend innumerable hours, and the parties much more money, on determining that particular defendant's . By using the reasonable person standard, courts instead use an objective tool and avoid such subjective evaluations. when attempting to determine liability.
Children 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. This is called the
defense of infancy: in Latin,
doli incapax. In some jurisdictions, 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, and in some jurisdictions, children can also be "
tried as an adult" for serious crimes, such as
murder, which causes the court to disregard the defendant's age.
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. Generally, the courts have reasoned that by not accepting mental illness as a bar to recovery, a potentially liable third party, such as a caregiver, will be more likely to protect the public. The courts have also stated the reason that members of the public are unable to identify a mentally ill person, as they can a child or someone with a physical disability.
Professionals When a person attempts a skilful act, the "reasonable person under the circumstances" test is elevated to a standard of whether the person acted how a "reasonable professional under the circumstances" would have, whether or not that person is actually a professional, has training, or has experience. Other factors also become relevant, such as the degree to which a 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 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.
Armed professionals The "reasonable officer" standard is a method often applied to law enforcement and other armed professions to help determine if a use of force was excessive. The test is whether an appropriately trained professional, knowing what the officer knew at the time and following guidelines (such as a
force continuum), would have used the same level of force or higher. If the level of force is justified, the quantity of force is usually presumed to have been necessary unless there are other factors. For example, if a trained police officer was justified in fatally shooting a suspect, the number of shots is presumed to have been necessary barring other factors, such as a reckless disregard of others' safety or that additional force was used when the suspect was no longer a threat.
Inexperience When anyone undertakes a skilful task that creates a risk to others, that person is 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==