Negligence - Physically and mentally impaired individuals

Learning Outcomes

This article explains how negligence law treats physically and mentally impaired individuals on the MBE, including:

• Understanding how the objective reasonable person standard is adjusted for physical disabilities and how to articulate the “reasonable person with the same disability” formulation on multiple‑choice questions
• Distinguishing physical disabilities from mental impairments, insanity, and low intelligence, and recognizing that mental conditions almost never reduce the standard of care on the exam
• Applying the doctrine of sudden incapacity by analyzing foreseeability, prior warnings, and the difference between chronic conditions and truly unforeseeable events such as first‑time heart attacks
• Evaluating how voluntary and involuntary intoxication are treated, and identifying when intoxication is analyzed like ordinary negligence versus sudden physical incapacity
• Determining the correct standard for child defendants, including children with physical or cognitive limitations and those engaged in adult activities such as driving
• Spotting high‑yield exam traps involving impaired defendants, including misclassification of impairments, incorrect adjustment of the standard, and failure to consider foreseeability
• Practicing a stepwise approach to MBE questions so you can classify the impairment, select the proper standard of care, and eliminate distractor answers that rely on sympathy rather than doctrine

MBE Syllabus

For the MBE, you are required to understand how physical and mental impairments affect the negligence standard of care, with a focus on the following syllabus points:

• The reasonable person standard and physical disabilities
• Mental impairments, insanity, and the objective standard
• Sudden physical or mental incapacity and foreseeability of harm
• Voluntary and involuntary intoxication as they relate to negligence
• Children’s standard of care, including children with disabilities
• How these rules interact with comparative or contributory negligence

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which standard of care applies to a defendant with a physical disability in a negligence action?
   1. The standard of a reasonable person with the same disability
   2. The standard of a reasonable person without the disability
   3. Strict liability
   4. The subjective standard of the defendant's actual abilities
2. How does the law generally treat mental illness or insanity in determining negligence liability?
   1. It excuses the defendant from liability
   2. It is treated the same as a physical disability
   3. It is not considered and the defendant is held to the ordinary reasonable person standard
   4. It results in strict liability
3. Which of the following is most likely to be a defense to negligence for a sudden loss of consciousness?
   1. Voluntary intoxication
   2. Foreseeable epileptic seizure
   3. Unforeseeable heart attack
   4. Chronic mental illness

Introduction

Negligence law uses a largely objective reasonable person standard to assess whether a defendant breached a duty of care. When a defendant is physically or mentally impaired, courts must decide whether to adjust this standard and, if so, how. This is a classic “trap” topic on the MBE: questions often turn on whether the impairment is physical or mental, and whether any incapacity was foreseeable.

Key Term: Standard of Care
The level of caution and conduct the law requires of a person in a given situation. In ordinary negligence, this is usually the conduct of a reasonably prudent person under the circumstances.

Key Term: Reasonable Person Standard
The objective legal standard used to judge conduct in negligence cases, based on how a hypothetical person of ordinary prudence would act in similar circumstances.

The Objective Standard and Individual Characteristics

The default rule is that the negligence standard is objective. Defendants are generally presumed to have:

• Ordinary intelligence
• Ordinary perception and memory
• Ordinary knowledge of common risks (e.g., that knives are sharp, that wet floors are slippery)

A defendant cannot usually argue, “I did the best I could given my low intelligence” or “I am naturally careless.” Those types of mental and emotional characteristics do not reduce the standard of care.

Key Term: Objective Standard
A standard that does not depend on a particular person’s actual mental abilities or subjective beliefs, but instead uses an external benchmark such as the reasonable person.

However, certain physical characteristics and age are taken into account in setting the applicable standard.

Key Term: Physical Disability
A bodily impairment that limits a person's physical abilities, such as blindness, deafness, or loss of limb. The reasonable person standard is modified to reflect these limitations.

The Reasonable Person Standard and Physical Disabilities

For individuals with a physical disability, the law compares their conduct to that of a hypothetical reasonable person with the same disability, not to a person without it. This is often described as “subjectivizing” the standard for physical traits while keeping it objective overall.

• A blind person must act as a reasonable blind person would.
• A person using a prosthetic leg must behave as a reasonable person with that prosthesis would.
• A defendant with limited mobility must take precautions that a reasonably prudent person with similar mobility would take.

Physical limitations affect what is reasonable, but they do not excuse the person from taking care altogether. The disabled defendant must still use reasonable care in light of their condition (using a cane, asking for assistance, avoiding high-risk activities they cannot safely perform, and so on).

Key Term: Subjective Standard
A standard that takes into account the particular characteristics or limitations of the specific person, such as their physical disability, while still requiring reasonable prudence.

Mental Impairments and the Standard of Care

Mental impairments—such as mental illness, intellectual disability, dementia, or psychotic disorders—are treated differently.

Key Term: Mental Impairment
A condition affecting a person's mind or cognitive function, such as insanity, mental illness, or intellectual disability.

Under the traditional rule, which you should apply on the MBE:

• Mental impairments do not lower the negligence standard.
• A defendant with mental illness or low intelligence is held to the same reasonable person standard as someone without that impairment.

This is true whether the impairment is chronic (e.g., schizophrenia) or episodic (e.g., a recurrent psychotic break), and whether or not the defendant was institutionalized. The defendant cannot avoid liability by arguing that their mental state prevented them from understanding or avoiding the risk.

Policy reasons the examiners may hint at:

• Mental conditions are difficult to diagnose and prove reliably.
• Allowing mental illness as a defense would shift losses from the impaired person (or their estate) to innocent victims.
• People who know they have a mental condition can often take precautions (medication, supervision, avoiding driving, etc.).

Some modern authorities have discussed narrow exceptions for sudden mental incapacity, but unless the question clearly tells you otherwise, treat mental illness as no defense to negligence on the MBE.

Sudden Incapacity and Foreseeability

Where incapacity is sudden and unforeseeable, the law may excuse liability. This is usually framed as a sudden physical incapacity, such as:

• An unexpected heart attack while driving
• A first-time seizure with no prior warning
• A previously unknown aneurysm causing loss of consciousness

Key Term: Sudden Incapacity
An abrupt loss of physical or mental function that could not reasonably have been anticipated or prevented. If truly unforeseeable, it may excuse what would otherwise be negligent conduct.

The key exam issues are:

• Foreseeability: Did the defendant know or should they have known about the risk of incapacity?
• Precautions: Did a reasonable person with their condition take adequate precautions (e.g., not driving, taking medication, arranging supervision)?

If the defendant had no reason to anticipate the incapacity, they are typically not negligent for conduct during the incapacitating episode. If they knew or should have known of the risk, they will usually be found negligent for engaging in dangerous activity at all (e.g., driving).

Intoxication

Intoxication is treated differently again.

Key Term: Voluntary Intoxication
Intoxication resulting from a person’s choice to consume alcohol or drugs. It does not reduce the negligence standard of care.

Key Term: Involuntary Intoxication
Intoxication that occurs without the person’s knowledge or against their will (for example, being secretly drugged). It may be treated like a physical condition for negligence purposes.

Rules to remember:

• Voluntary intoxication is not treated as a disability. An intoxicated person is held to the same standard as a sober reasonable person. Choosing to drink or take drugs does not excuse careless conduct.
• The defendant cannot argue, “I was too drunk to realize the danger.”
• If intoxication is involuntary (e.g., their drink was spiked without their knowledge), many courts treat it similarly to sudden physical incapacity and will ask whether the resulting conduct was reasonably foreseeable.

The MBE usually tests voluntary intoxication: assume the ordinary reasonable person standard applies.

Children with Disabilities

Children are not held to the adult standard in most situations.

Key Term: Child Standard
The standard of care applied to children, usually that of a reasonable child of similar age, intelligence, and experience under like circumstances.

A child’s conduct is compared to that of a reasonable child of similar age, intelligence, and experience. Exam points:

• A child’s physical disabilities are taken into account, just as with adults. A child who is blind is compared to a reasonable blind child of similar age and experience.
• A child’s mental impairments are generally folded into the analysis of their intelligence and experience; however, you should still treat the rule as: mental impairment does not excuse negligence.
• Adult activities: When a child engages in an inherently dangerous adult activity (most commonly driving a car, but also sometimes operating a motorboat, snowmobile, or similar vehicle), many jurisdictions hold the child to the adult reasonable person standard.

Key Term: Adult Activity
A high-risk activity normally undertaken only by adults, such as driving a motor vehicle. A child performing an adult activity is usually held to the adult standard of care.

Foreseeability and Impaired Defendants

Key Term: Foreseeability
The idea that liability in negligence depends on whether a reasonable person in the defendant’s position would anticipate the risk of harm and take steps to prevent it.

With impaired defendants, foreseeability comes up in two main ways:

• Did the defendant know they had a condition that made the activity especially dangerous (e.g., epilepsy, severe diabetes, serious heart disease)?
• Would a reasonable person with that condition foresee the risk of sudden incapacitation and refrain from engaging in the high-risk activity (like driving) or take extra precautions?

If the answer is yes, engaging in that activity at all can be negligent—even if the precise way the accident happened was unexpected.

Worked Example 1.1

A defendant with a prosthetic leg trips and causes another person to fall. In a negligence action, what standard applies?

Answer:
The defendant is compared to a reasonable person with a prosthetic leg. If the defendant took reasonable precautions given the disability, there is no breach.

Worked Example 1.2

A driver with a long history of epileptic seizures has a seizure while driving, loses control, and injures a pedestrian. Is the driver liable?

Answer:
Yes. Because the driver knew of the risk, the seizure was foreseeable. The driver is held to the standard of a reasonable person with epilepsy, including taking precautions such as not driving.

Worked Example 1.3

A person with schizophrenia, during a psychotic episode, negligently causes a fire. Is mental illness a defense?

Answer:
No. Mental illness or insanity does not excuse negligence. The defendant is held to the ordinary reasonable person standard.

Worked Example 1.4

A middle‑aged driver with no prior cardiac history suddenly suffers a heart attack while driving carefully within the speed limit. The car veers off the road and injures a pedestrian. The driver had never before experienced chest pain or other warning signs. Is the driver negligent?

Answer:
Probably not. The heart attack was sudden and unforeseeable. A reasonable person with no prior warning symptoms would not anticipate incapacitation, so the driver’s sudden loss of control is not a breach of duty.

Worked Example 1.5

A diabetic driver has been warned that failing to eat regularly may cause sudden loss of consciousness. Knowing this, she skips meals and drives a long distance. She blackouts and causes a crash. On the MBE, how should this be analyzed?

Answer:
The blackout was foreseeable because of her known condition and warnings. A reasonable person with diabetes who knows of this risk would not drive (or would manage food and insulin to avoid incapacitation). Driving anyway is a breach of the standard of care.

Worked Example 1.6

A 13‑year‑old child with mild intellectual disability is riding a bicycle on the sidewalk at a normal speed and collides with a pedestrian. The jurisdiction applies the usual child standard except for adult activities. What standard applies?

Answer:
The child is held to the standard of a reasonable child of similar age, intelligence, and experience. Riding a bicycle is not an adult activity, so the child standard applies. The mild intellectual disability is reflected in the “similar intelligence” part of the test; it does not excuse obviously careless behavior.

Exam Warning

The MBE often tests the distinction between physical and mental impairments.

• Physical disabilities adjust the reasonable person standard to a reasonable person with that disability.
• Mental impairments (including insanity and low intelligence) do not change the standard; the defendant is held to the ordinary reasonable person standard.
• Voluntary intoxication is treated like mental impairment for this purpose: no adjustment to the standard of care.

Common traps:

• Treating mental illness like a physical disability (do not do this unless the problem explicitly tells you to apply a different rule).
• Forgetting that children engaged in adult activities are held to the adult standard.
• Treating voluntary intoxication as if it were sudden incapacity.

Revision Tip

When you see an impaired defendant:

• Step 1: Classify the impairment. Is it physical, mental, intoxication, age‑related, or a mix?
• Step 2: Ask whether the incapacity episode (if any) was foreseeable. Prior history of the condition usually makes it foreseeable.
• Step 3: Apply the correct standard:
  • Physical impairment → reasonable person with that impairment
  • Mental impairment → ordinary reasonable person
  • Voluntary intoxication → ordinary reasonable person
  • Sudden unforeseeable physical incapacity → likely no negligence
  • Child → reasonable child of similar age, intelligence, and experience (adult standard for adult activities)

Key Point Checklist

This article has covered the following key knowledge points:

• The reasonable person standard is objective, but it adjusts for physical disabilities.
• Defendants with physical disabilities are compared to a reasonable person with the same disability.
• Mental impairments, including insanity and low intelligence, do not change the standard of care on the MBE.
• Sudden, unforeseeable physical incapacity (such as an unexpected heart attack) can excuse negligence; foreseeability is important.
• Defendants who know of a risk of sudden incapacity (e.g., epilepsy, unmanaged diabetes) are expected to avoid dangerous activities like driving.
• Voluntary intoxication is not a defense; an intoxicated person is held to the same standard as a sober reasonable person.
• Involuntary intoxication may be analyzed similarly to sudden physical incapacity, depending on foreseeability.
• Children are held to the standard of a reasonable child of similar age, intelligence, and experience; for adult activities, many courts apply the adult standard.
• Children’s physical disabilities are taken into account; mental impairments generally are not an excuse.
• The MBE frequently tests the difference between physical and mental impairments and the role of foreseeability in sudden incapacity scenarios.

Key Terms and Concepts

• Standard of Care
• Reasonable Person Standard
• Objective Standard
• Subjective Standard
• Physical Disability
• Mental Impairment
• Sudden Incapacity
• Voluntary Intoxication
• Involuntary Intoxication
• Child Standard
• Adult Activity
• Foreseeability