What a Negligence Plaintiff Must Establish

Q: What is res ipsa loquitur?

Latin for the thing speaks for itself . It lets a plaintiff use circumstantial evidence to raise a presumption of negligence when the accident normally wouldn't happen without negligence and the cause was in the defendant's control.

Last reviewed: October 17, 2026. This article is general information, not legal advice. Negligence is mostly state law, so the exact wording of each element and the fault rules differ between states.

Whether you're studying for an exam or wondering whether you have a real claim after an accident, the same question comes up: what does the injured person actually have to prove? Here's a plain-English guide to the elements, with everyday examples.

Short answer: in a negligence case, the plaintiff must establish four elements: (1) the defendant owed them a duty of care, (2) the defendant breached that duty by failing to act as a reasonable person would, (3) the breach caused the harm, both as a matter of fact and as a legally recognised (proximate) cause, and (4) the plaintiff suffered actual damages. If any element is missing, the claim fails.

1. Duty of care

A duty is a legal obligation to act reasonably toward others. Wex explains that "there is a duty to act reasonably", and lists situations that can create a duty, including when the defendant created the risk, voluntarily took on the job of protecting someone, knew their conduct would harm the plaintiff, or had a special relationship such as business owner and customer or doctor and patient.

Examples: drivers owe other road users a duty to drive carefully; stores owe customers a duty to keep aisles reasonably safe.

2. Breach of duty

A breach happens when the defendant's conduct falls below what a reasonable person would have done in the same situation. Wex notes that juries ask "what a reasonable person would have done in the defendant's situation." Factors include how likely and how serious the harm was, and how hard it would have been to prevent it.

Examples: texting while driving; leaving a spill on a store floor for hours without a warning sign.

Negligence per se

If the defendant broke a safety statute, breach may be established automatically. Wex explains that a defendant who violates a statute or regulation without an excuse "is automatically considered to have breached their duty of care", and cites Restatement (Third) of Torts § 14: the statute must be designed to protect against the type of harm that happened, and the plaintiff must be someone it was meant to protect.

3. Causation

Causation has two parts, and the plaintiff must prove both.

Cause in fact ("but for" cause): the harm wouldn't have happened but for the defendant's conduct.
Proximate cause: the harm was a foreseeable result of the conduct, close enough that the law holds the defendant responsible. Wex's example: someone throws a rock off a high-rise balcony without looking and hits a pedestrian below. The harm was foreseeable, so the thrower is the proximate cause. Intervening events, such as a third party's actions, can break the chain.

4. Damages

The plaintiff must have suffered actual harm. According to Wex, harm is typically bodily injury or damage to property; purely economic loss usually isn't enough, and some states recognise emotional distress. Carelessness that causes no harm isn't a negligence claim, however dangerous it was.

Compensable damages commonly include medical bills, lost wages, property repair and, in injury cases, pain and suffering. Our guide to what makes a settlement offer reasonable explains how these are valued.

How the plaintiff proves it

Burden of proof: in civil cases, usually a preponderance of the evidence. Wex describes this as convincing the fact finder that there is a greater than 50% chance that the claim is true.
Evidence: photos, police or incident reports, witness statements, medical records, expert testimony.
Res ipsa loquitur: where direct evidence is missing, a plaintiff may rely on the inference that the accident wouldn't normally happen without negligence and the cause was under the defendant's control.

Defenses that can reduce or defeat a claim

Comparative negligence: damages are reduced by the plaintiff's share of fault. Some states use a "pure" rule; others bar recovery once the plaintiff's fault reaches a threshold (a 50% or 51% bar).
Contributory negligence: in the few jurisdictions that still use it, any fault by the plaintiff can bar recovery.
Statute of limitations: each state sets a deadline to sue. In California, for example, personal injury claims generally must be brought within two years under Code of Civil Procedure § 335.1.

Putting it together: a quick example

A driver runs a red light and hits your car. Duty: drivers must drive carefully. Breach: running the light (and possibly negligence per se, as a traffic violation). Causation: but for running the light, the crash wouldn't have happened, and a crash is a foreseeable result. Damages: your medical bills, lost wages and car repairs. If you were speeding at the time, comparative negligence might reduce your recovery.

For real-world situations, see our guides on whether you need a lawyer for a minor car accident and who the plaintiff is in a criminal case.

What are the four elements of negligence?

Duty, breach, causation and damages. Some sources split causation into two parts, cause in fact and proximate cause, which is why you may also see the elements listed as five. Cornell's Wex lists them that way.

What standard of proof applies?

In a civil negligence case, the plaintiff usually has to prove each element by a preponderance of the evidence: convincing the judge or jury that the claim is more likely true than not. That is a lower standard than beyond a reasonable doubt in criminal cases.

What is negligence per se?

When a defendant breaks a safety law designed to protect people like the plaintiff from the kind of harm that happened, many courts treat the breach as established. The plaintiff still has to prove causation and damages. Traffic violations are a common example.

What if the plaintiff was partly at fault?

Most states use comparative negligence, which reduces damages by the plaintiff's share of fault, and some bar recovery past a threshold. A few jurisdictions still use contributory negligence, where any fault by the plaintiff can bar recovery entirely; Cornell's Wex names Alabama, Maryland, North Carolina, Virginia and the District of Columbia.

What is res ipsa loquitur?

Latin for the thing speaks for itself. It lets a plaintiff use circumstantial evidence to raise a presumption of negligence when the accident normally wouldn't happen without negligence and the cause was in the defendant's control.

Sources

Negligence: Cornell LII Wex
Negligence per se (citing Restatement (Third) of Torts §§ 14–15): Cornell LII Wex
Res ipsa loquitur: Cornell LII Wex
Comparative negligence: Cornell LII Wex
Contributory negligence: Cornell LII Wex
Preponderance of the evidence: Cornell LII Wex
California Code of Civil Procedure § 335.1 (two-year limit for personal injury): FindLaw copy of the statute

In a Negligence Case, the Plaintiff Must Establish: Duty, Breach, Causation and Damages