UBE Negligence: Causation

Last updated: May 2, 2026

Negligence: Causation questions are one of the highest-leverage areas to study for the UBE. This guide breaks down the rule, the elements you need to recognize, the named traps that catch most students, and a memory aid that scales to test day. Read it once, then practice the same sub-topic adaptively in the app.

The rule

To recover in negligence, the plaintiff must prove both actual cause (cause-in-fact) and proximate cause (legal cause). Actual cause is generally established by the but-for test: the harm would not have occurred but for the defendant's breach. Where multiple sufficient causes operate concurrently, courts apply the substantial-factor test (Restatement (Second) of Torts §431). Proximate cause limits liability to harms that are a foreseeable result of the breach (Restatement (Third) of Torts: Liability for Physical and Emotional Harm §29 — the 'scope of liability' or 'risk' test). Intervening forces break the chain only if they are unforeseeable; foreseeable intervening causes do not cut off liability.

Elements breakdown

But-For Causation (Cause-in-Fact, Default Test)

The plaintiff must show the injury would not have occurred absent the defendant's negligent conduct.

  • Defendant breached a duty
  • Without the breach, harm would not have occurred
  • Plaintiff's injury is the same harm at issue

Common examples:

  • Driver runs a red light and strikes pedestrian who would otherwise have crossed safely
  • Doctor fails to diagnose treatable cancer; patient dies from progression

Substantial-Factor Test (Multiple Sufficient Causes)

Where two or more independently sufficient causes combine to produce indivisible harm, each is a cause-in-fact if it was a substantial factor in bringing about the result.

  • Two or more forces operate concurrently
  • Each force alone would have caused the harm
  • Defendant's conduct was a substantial factor
  • Harm is indivisible

Common examples:

  • Two negligently set fires merge and burn plaintiff's barn
  • Two polluters discharge toxins each sufficient to kill fish

Alternative Liability (Summers v. Tice Doctrine)

When two or more defendants act negligently and only one caused the harm but the plaintiff cannot identify which, the burden shifts to each defendant to disprove causation.

  • Two or more defendants acted negligently
  • Only one (or some) caused plaintiff's harm
  • Plaintiff cannot identify which defendant
  • All possible tortfeasors joined as defendants

Common examples:

  • Two hunters negligently shoot toward plaintiff; one bullet strikes him

Loss-of-Chance Doctrine (Medical Malpractice)

In medical malpractice, a plaintiff may recover for the reduction in chance of survival or recovery caused by the defendant's negligence, even where the original chance was below 50%.

  • Defendant breached medical standard of care
  • Plaintiff had a measurable pre-existing chance of recovery
  • Breach reduced that chance
  • Damages proportional to lost chance

Common examples:

  • Radiologist misreads scan, dropping survival odds from 40% to 15%

Proximate Cause — Foreseeability / Scope-of-Risk

The defendant is liable only for harms within the scope of the foreseeable risk created by the negligent conduct.

  • Harm of a type the breach risked
  • Plaintiff a foreseeable victim
  • No unforeseeable superseding cause
  • Manner of harm need not be foreseeable in detail

Common examples:

  • Negligently stored gasoline ignites; foreseeable fire damage recoverable
  • Eggshell plaintiff: extent of harm need not be foreseeable

Intervening and Superseding Causes

A foreseeable intervening cause does not break the causal chain; an unforeseeable, independent intervening force is superseding and cuts off liability.

  • Independent force occurs after defendant's act
  • Force contributes to plaintiff's harm
  • Foreseeability determines whether superseding

Common examples:

  • Subsequent medical malpractice during treatment of original injury — foreseeable, not superseding
  • Negligent rescue attempts — foreseeable
  • Intentional criminal act by third party — usually superseding unless risk of crime was the very risk created

Eggshell-Plaintiff Rule

The defendant takes the plaintiff as found; full damages flow even if the plaintiff's pre-existing condition makes the harm far worse than expected.

  • Defendant's conduct was a proximate cause of some harm
  • Plaintiff had a latent vulnerability
  • Extent of harm need not be foreseeable

Common examples:

  • Minor collision triggers severe hemophilic bleeding

Common patterns and traps

The But-For-vs-Substantial-Factor Switch

When the facts present two independently sufficient causes (two fires, two pollutants, two impacts), but-for fails because each defendant can point to the other and claim the harm would have occurred anyway. The MBE expects you to switch to the substantial-factor test under Restatement (Second) §431. Candidates who mechanically apply but-for here will choose a wrong-cause answer.

A choice that says 'No, because the harm would have occurred even without defendant's conduct' is a substantial-factor trap when two sufficient causes are present.

The Foreseeable-Intervenor Distractor

A distractor frames a routine intervening force — a negligent rescuer, subsequent medical malpractice, ordinary negligence by a third driver — as if it 'broke the chain.' Under majority law, foreseeable intervenors do not supersede; only unforeseeable, independent forces (acts of God, intentional crimes outside the scope of risk) do. The trap rewards candidates who confuse 'intervening' with 'superseding.'

'No, because the doctor's malpractice was an independent cause' — wrong, because subsequent medical malpractice is a foreseeable consequence of the original injury.

The Eggshell-Plaintiff Misapplication

Candidates remember that an eggshell plaintiff recovers full damages but apply the rule to extend proximate cause to any plaintiff. Eggshell only governs the EXTENT of harm to a foreseeable victim of a foreseeable type of harm — it does not transform an unforeseeable plaintiff or unforeseeable type into a foreseeable one.

'Yes, because the defendant takes the plaintiff as found' — used to justify recovery for an unforeseeable plaintiff. The rule does not stretch that far.

The Loss-of-Chance Sleight

In medical malpractice, the patient's pre-existing prognosis was below 50% and the defendant misses a diagnosis. Traditional but-for analysis denies recovery (the patient probably would have died anyway). The majority of jurisdictions now allow loss-of-chance damages, proportional to the reduction. A distractor will phrase the answer as 'No, because plaintiff cannot prove by a preponderance the breach caused the death.'

'No, because patient would more likely than not have died regardless' — correct under traditional but-for, wrong under majority loss-of-chance treatment.

The Unforeseeable-Plaintiff (Cardozo) Trap

Where the plaintiff is outside the foreseeable zone of danger, Cardozo's *Palsgraf* majority denies a duty (no proximate cause / no duty owed). Distractors will offer recovery on a but-for theory or on an Andrews-style 'all consequences' rationale. The MBE follows Cardozo.

'Yes, because defendant's negligence was a but-for cause of plaintiff's injury' — ignores the duty/foreseeability limit on the plaintiff's identity.

How it works

Treat causation as two separate inquiries: did the defendant's breach in fact produce the injury, and is it fair to hold the defendant legally responsible for it? Suppose Reyes negligently leaves a propane tank uncapped at a construction site. A worker later flicks a lighter to check a fuse and the site explodes. But-for causation is satisfied because, without the leak, no explosion. Proximate cause is satisfied because fire and explosion are precisely the foreseeable risks of an uncapped propane tank — the manner (a lighter rather than a spark from machinery) is irrelevant. If instead a meteor had struck the tank, the meteor would be an unforeseeable superseding cause and Reyes would not be liable for that explosion. Always run the but-for test first; if two sufficient causes converge or you cannot identify which defendant fired the shot, switch to the substantial-factor or alternative-liability framework.

Worked examples

Worked Example 1

Will Patel prevail against Reyes on a negligence theory?

  • A Yes, because Reyes's negligence was a substantial factor in causing the destruction of the barn. ✓ Correct
  • B No, because the barn would have burned even if Reyes had not been negligent.
  • C No, because the lightning strike was a superseding cause that broke the chain of causation.
  • D Yes, but only for half the value of the barn, because two independent fires contributed to the loss.

Why A is correct: This is the classic two-fires fact pattern (Restatement (Second) of Torts §432(2)). Where two forces, each independently sufficient to cause indivisible harm, combine, the but-for test fails as to each defendant. Courts apply the substantial-factor test instead: Reyes's negligently set fire was a substantial factor in destroying the barn, so causation is satisfied. Joint and several liability typically gives Patel full recovery against Reyes, who can seek contribution from Liu.

Why each wrong choice fails:

  • B: This applies the but-for test mechanically. Where two sufficient causes converge, but-for cannot establish causation because each defendant points to the other; the substantial-factor test governs instead. (The But-For-vs-Substantial-Factor Switch)
  • C: Lightning is a natural force, but it does not supersede where the defendant's negligence remained a substantial factor in producing the same indivisible harm. Superseding cause requires an unforeseeable break that renders the defendant's negligence causally irrelevant — not the case here. (The Foreseeable-Intervenor Distractor)
  • D: The harm is indivisible — the barn was destroyed once, not twice. Joint and several liability allows full recovery against Reyes; apportionment between tortfeasors is handled in contribution, not by halving the plaintiff's verdict.
Worked Example 2

For which injuries is Liu liable?

  • A Only the concussion, because Dr. Reyes's malpractice was an independent intervening cause.
  • B Only the concussion, because kidney damage from medication is not a foreseeable consequence of a car collision.
  • C Both the concussion and the kidney damage, because subsequent negligent medical treatment is a foreseeable intervening cause. ✓ Correct
  • D Both the concussion and the kidney damage, only if Dr. Reyes is judgment-proof and cannot satisfy a separate verdict.

Why C is correct: Under the majority rule and Restatement (Second) of Torts §457, subsequent negligent medical treatment of an injury caused by the defendant is a foreseeable consequence of placing the plaintiff in need of medical care. Foreseeable intervening causes do not supersede the original tortfeasor's liability. Liu therefore remains the proximate cause of the kidney damage; Liu can seek contribution from Reyes but cannot use Reyes's negligence to escape liability to Patel.

Why each wrong choice fails:

  • A: This conflates 'intervening' with 'superseding.' Subsequent medical malpractice is a paradigmatic foreseeable intervenor; it does not break the causal chain. (The Foreseeable-Intervenor Distractor)
  • B: Foreseeability of the type of harm is assessed at the level of generality of 'further injury during medical treatment,' not the precise mechanism. The eggshell/scope-of-risk rules do not require foreseeability of the specific kidney pathology. (The Eggshell-Plaintiff Misapplication)
  • D: Liu's liability does not depend on Reyes's solvency. Joint and several liability (or comparative apportionment in many jurisdictions) makes Liu fully liable to Patel; collectability between tortfeasors is a contribution issue.
Worked Example 3

What is the most likely result?

  • A The estate recovers nothing, because Patel could not have proven by a preponderance of the evidence that Dr. Liu's negligence caused her death.
  • B The estate recovers full wrongful-death damages, because Dr. Liu was a but-for cause of the loss of Patel's life.
  • C The estate recovers damages proportional to the reduction in Patel's chance of survival. ✓ Correct
  • D The estate recovers nothing, because the underlying tumor, not Dr. Liu's conduct, was the proximate cause of death.

Why C is correct: In a majority of jurisdictions, the loss-of-chance doctrine permits recovery in medical-malpractice cases where the defendant's negligence reduced the plaintiff's chance of recovery, even when the original chance was below 50%. Damages are calibrated to the lost chance — here, the 27-percentage-point reduction (from 35% to 8%) — multiplied by the value of the underlying wrongful-death damages. This avoids the all-or-nothing problem of strict but-for analysis where the plaintiff's prognosis was already poor.

Why each wrong choice fails:

  • A: This applies the traditional but-for test that the majority of jurisdictions have rejected in this exact context. Loss-of-chance was developed precisely to avoid denying recovery whenever the pre-existing prognosis was below 50%. (The Loss-of-Chance Sleight)
  • B: Full damages overstate the recovery. Even under loss-of-chance, the estate recovers only the proportional value of the chance lost, not as if the doctor caused a 100%-survivable patient to die.
  • D: This treats the underlying disease as a superseding cause, but the tumor was the very condition the defendant was retained to diagnose. The negligent failure to diagnose is precisely within the scope of the risk created by the breach. (The Foreseeable-Intervenor Distractor)

Memory aid

Two gates, in order: BUT-FOR (or substantial factor / alternative liability) → FORESEEABLE SCOPE OF RISK. If both gates open, causation is met. Mnemonic for proximate-cause flagging: 'TYPE, VICTIM, NOT-SUPERSEDED' — type of harm foreseeable, plaintiff a foreseeable victim, no unforeseeable break in the chain.

Key distinction

Cause-in-fact (factual link) versus proximate cause (policy-driven foreseeability limit). A defendant whose breach is a but-for cause can still escape liability if the harm is outside the scope of the foreseeable risk; conversely, a defendant who is a but-for cause of a foreseeable harm cannot escape just because the chain of events is unusual.

Summary

Negligence causation is a two-step gate: factual causation (but-for, substantial factor, or alternative liability) followed by proximate cause (foreseeable type of harm, foreseeable plaintiff, no unforeseeable superseding force).

Practice negligence: causation adaptively

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Frequently asked questions

What is negligence: causation on the UBE?

To recover in negligence, the plaintiff must prove both actual cause (cause-in-fact) and proximate cause (legal cause). Actual cause is generally established by the but-for test: the harm would not have occurred but for the defendant's breach. Where multiple sufficient causes operate concurrently, courts apply the substantial-factor test (Restatement (Second) of Torts §431). Proximate cause limits liability to harms that are a foreseeable result of the breach (Restatement (Third) of Torts: Liability for Physical and Emotional Harm §29 — the 'scope of liability' or 'risk' test). Intervening forces break the chain only if they are unforeseeable; foreseeable intervening causes do not cut off liability.

How do I practice negligence: causation questions?

The fastest way to improve on negligence: causation is targeted, adaptive practice — working questions that focus on your specific weak spots within this sub-topic, getting immediate feedback, and revisiting items you missed on a spaced-repetition schedule. Neureto's adaptive engine does this automatically across the UBE; start a free 7-day trial to see your sub-topic mastery climb in real time.

What's the most important distinction to remember for negligence: causation?

Cause-in-fact (factual link) versus proximate cause (policy-driven foreseeability limit). A defendant whose breach is a but-for cause can still escape liability if the harm is outside the scope of the foreseeable risk; conversely, a defendant who is a but-for cause of a foreseeable harm cannot escape just because the chain of events is unusual.

Is there a memory aid for negligence: causation questions?

Two gates, in order: BUT-FOR (or substantial factor / alternative liability) → FORESEEABLE SCOPE OF RISK. If both gates open, causation is met. Mnemonic for proximate-cause flagging: 'TYPE, VICTIM, NOT-SUPERSEDED' — type of harm foreseeable, plaintiff a foreseeable victim, no unforeseeable break in the chain.

What's a common trap on negligence: causation questions?

Skipping straight to proximate cause without first establishing cause-in-fact

What's a common trap on negligence: causation questions?

Treating any unusual intervening event as superseding when it is actually foreseeable

Related UBE sub-topics

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