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7.3 Negligence

Learning Objectives

  1. Understand how the duty of due care relates to negligence.
  2. Distinguish between actual and proximate cause.
  3. Explain the primary defenses to a claim of negligence.

Elements of Negligence

Physical harm need not be intentionally caused. A pedestrian knocked over by an automobile does not hurt less because the driver intended no wrong but was merely careless. The law imposes a duty of care on all of us in our everyday lives. Accidents caused by negligence are actionable.

Determining negligenceA breach of the duty of due care. is not always easy. If a driver runs a red light, we can say that he is negligent because a driver must always be careful to ascertain whether the light is red and be able to stop if it is. Suppose that the driver was carrying a badly injured person to a nearby hospital and that after slowing down at an intersection, went through a red light, blowing his horn, whereupon a driver to his right, seeing him, drove into the intersection anyway and crashed into him. Must one always stop at a red light? Is proof that the light was red always proof of negligence? Usually, but not always: negligence is an abstract concept that must always be applied to concrete and often widely varying sets of circumstances. Whether someone was or was not negligent is almost always a question of fact for a jury to decide. Rarely is it a legal question that a judge can settle.

The tort of negligence has four elements: (1) a duty of due care that the defendant had, (2) the breach of the duty of due careAny act that fails to meet a standard of the person’s duty of due care toward others. The standard is usually described as the standard of behavior that is expected of a hypothetical “reasonable person” under the circumstances. Certain professionals, however, may be held to a higher standard than the ordinary person., (3) connection between cause and injury, and (4) actual damage or loss. Even if a plaintiff can prove each of these aspects, the defendant may be able to show that the law excuses the conduct that is the basis for the tort claim. We examine each of these factors below.

Standard of Care

Not every unintentional act that causes injury is negligent. If you brake to a stop when you see a child dart out in front of your car, and if the noise from your tires gives someone in a nearby house a heart attack, you have not acted negligently toward the person in the house. The purpose of the negligence standard is to protect others against the risk of injury that foreseeably would ensue from unreasonably dangerous conduct.

Given the infinite variety of human circumstances and conduct, no general statement of a reasonable standard of care is possible. Nevertheless, the law has tried to encapsulate it in the form of the famous standard of “the reasonable man.” This fictitious person “of ordinary prudence” is the model that juries are instructed to compare defendants with in assessing whether those defendants have acted negligently. Analysis of this mythical personage has baffled several generations of commentators. How much knowledge must he have of events in the community, of technology, of cause and effect? With what physical attributes, courage, or wisdom is this nonexistent person supposedly endowed? If the defendant is a person with specialized knowledge, like a doctor or an automobile designer, must the jury also treat the “reasonable man” as having this knowledge, even though the average person in the community will not? (Answer: in most cases, yes.)

Despite the many difficulties, the concept of the reasonable man is one on which most negligence cases ultimately turn. If a defendant has acted “unreasonably under the circumstances” and his conduct posed an unreasonable risk of injury, then he is liable for injury caused by his conduct. Perhaps in most instances, it is not difficult to divine what the reasonable man would do. The reasonable man stops for traffic lights and always drives at reasonable speeds, does not throw baseballs through windows, performs surgical operations according to the average standards of the medical profession, ensures that the floors of his grocery store are kept free of fluids that would cause a patron to slip and fall, takes proper precautions to avoid spillage of oil from his supertanker, and so on. The "reasonable man" standard imposes hindsight on the decisions and actions of people in society; the circumstances of life are such that courts may sometimes impose a standard of due care that many people might not find reasonable.

Duty of Care and Its Breach

The law does not impose on us a duty to care for every person. If the rule were otherwise, we would all, in this interdependent world, be our brothers’ keepers, constantly unsure whether any action we took might subject us to liability for its effect on someone else. The law copes with this difficulty by limiting the number of people toward whom we owe a duty to be careful.

In general, the law imposes no obligation to act in a situation to which we are strangers. We may pass the drowning child without risking a lawsuit. But if we do act, then the law requires us to act carefully. The law of negligence requires us to behave with due regard for the foreseeable consequences of our actions in order to avoid unreasonable risks of injury.

During the course of the twentieth century, the courts have constantly expanded the notion of “foreseeability,” so that today many more people are held to be within the zone of injury than was once the case. For example, it was once believed that a manufacturer or supplier owed a duty of care only to immediate purchasers, not to others who might use the product or to whom the product might be resold. This limitation was known as the rule of privity. And users who were not immediate purchasers were said not to be in privity with a supplier or manufacturer. In 1916, Judge Benjamin N. Cardozo, then on the New York Court of Appeals, penned an opinion in a celebrated case that exploded the theory of privity, though it would take half a century before the last state—Mississippi in 1966—would fall in line.

Determining a duty of care can be a vexing problem. Physicians, for example, are bound by principles of medical ethics to respect the confidences of their patients. Suppose a patient tells a psychiatrist that he intends to kill his girlfriend. Does the physician then have a higher legal duty to warn prospective victim? The California Supreme Court has said yes.Tarasoff v. Regents of University of California, 551 P.2d 334 (Calif. 1976).

Establishing a breach of the duty of due care where the defendant has violated a statute or municipal ordinance is eased considerably with the doctrine of negligence per seAn act of the defendant that violates a statute regulation or ordinance can be used to establish a breach of the duty of due care., a doctrine common to all US state courts. If a legislative body sets a minimum standard of care for particular kinds of acts to protect a certain set of people from harm and a violation of that standard causes harm to someone in that set, the defendant is negligent per se. If Harvey is driving sixty-five miles per hour in a fifty-five-mile-per-hour zone when he crashes into Haley’s car and the police accident report establishes that or he otherwise admits to going ten miles per hour over the speed limit, Haley does not have to prove that Harvey has breached a duty of due care. She will only have to prove that the speeding was an actual and proximate cause of the collision and will also have to prove the extent of the resulting damages to her.

Causation: Actual Cause and Proximate Cause

“For want of a nail, the kingdom was lost,” as the old saying has it. Virtually any cause of an injury can be traced to some preceding cause. The problem for the law is to know when to draw the line between causes that are immediate and causes too remote for liability reasonably to be assigned to them. In tort theory, there are two kinds of causes that a plaintiff must prove: actual cause and proximate cause. Actual cause (causation in fact)The actual cause of negligence is sometimes called the “but for” event that is a breach of duty on the part of the defendant. can be found if the connection between the defendant’s act and the plaintiff’s injuries passes the “but for” test: if an injury would not have occurred “but for” the defendant’s conduct, then the defendant is the cause of the injury. Still, this is not enough causation to create liability. The injuries to the plaintiff must also be foreseeable, or not “too remote,” for the defendant’s act to create liability. This is proximate causeSometimes known as legal cause, proximate cause must be shown as well as actual cause, so that an act of the defendant will not result in liability if the consequences of the negligent act are too remote or unforeseeable.: a cause that is not too remote or unforseeable.

Suppose that the person who was injured was not one whom a reasonable person could have expected to be harmed. Such a situation was presented in one of the most famous US tort cases, Palsgraf v. Long Island Railroad (Section 7.5 "Cases"), which was decided by Judge Benjamin Cardozo. Although Judge Cardozo persuaded four of his seven brethren to side with his position, the closeness of the case demonstrates the difficulty that unforeseeable consequences and unforeseeable plaintiffs present.


For a plaintiff to win a tort case, she must allege and prove that she was injured. The fear that she might be injured in the future is not a sufficient basis for a suit. This rule has proved troublesome in medical malpractice and industrial disease cases. A doctor’s negligent act or a company’s negligent exposure of a worker to some form of contamination might not become manifest in the body for years. In the meantime, the tort statute of limitations might have run out, barring the victim from suing at all. An increasing number of courts have eased the plaintiff’s predicament by ruling that the statute of limitations does not begin to run until the victim discovers that she has been injured or contracted a disease.

The law allows an exception to the general rule that damages must be shown when the plaintiff stands in danger of immediate injury from a hazardous activity. If you discover your neighbor experimenting with explosives in his basement, you could bring suit to enjoin him from further experimentation, even though he has not yet blown up his house—and yours.

Problems of Proof

The plaintiff in a tort suit, as in any other, has the burden of proving his allegations.

He must show that the defendant took the actions complained of as negligent, demonstrate the circumstances that make the actions negligent, and prove the occurrence and extent of injury. Factual issues are for the jury to resolve. Since it is frequently difficult to make out the requisite proof, the law allows certain presumptions and rules of evidence that ease the plaintiff’s task, on the ground that without them substantial injustice would be done. One important rule goes by the Latin phrase res ipsa loquiturLiterally, “the thing speaks for itself.” In tort cases, res ipsa loquitur creates a presumption that the defendant was negligent because he or she was in exclusive control of the situation and that the plaintiff would not have suffered injury but for someone’s negligence. Res ipsa loquitur shifts the burden to the defendant to prove that he or she was not negligent., meaning “the thing speaks for itself.” The best evidence is always the most direct evidence: an eyewitness account of the acts in question. But eyewitnesses are often unavailable, and in any event they frequently cannot testify directly to the reasonableness of someone’s conduct, which inevitably can only be inferred from the circumstances.

In many cases, therefore, circumstantial evidenceEvidence that is not “direct” but that provides judges and juries with facts that tend to show legal liability. (evidence that is indirect) will be the only evidence or will constitute the bulk of the evidence. Circumstantial evidence can often be quite telling: though no one saw anyone leave the building, muddy footprints tracing a path along the sidewalk are fairly conclusive. Res ipsa loquitur is a rule of circumstantial evidence that permits the jury to draw an inference of negligence. A common statement of the rule is the following: “There must be reasonable evidence of negligence but where the thing is shown to be under the management of the defendant or his servants, and the accident is such as in the ordinary course of things does not happen if those who have the management use proper care, it affords reasonable evidence, in the absence of explanation by the defendants, that the accident arose from want of care.”Scott v. London & St. Katherine Docks Co., 3 H. & C. 596, 159 Eng.Rep. 665 (Q.B. 1865).

If a barrel of flour rolls out of a factory window and hits someone, or a soda bottle explodes, or an airplane crashes, courts in every state permit juries to conclude, in the absence of contrary explanations by the defendants, that there was negligence. The plaintiff is not put to the impossible task of explaining precisely how the accident occurred. A defendant can always offer evidence that he acted reasonably—for example, that the flour barrel was securely fastened and that a bolt of lightning, for which he was not responsible, broke its bands, causing it to roll out the window. But testimony by the factory employees that they secured the barrel, in the absence of any further explanation, will not usually serve to rebut the inference. That the defendant was negligent does not conclude the inquiry or automatically entitle the plaintiff to a judgment. Tort law provides the defendant with several excuses, some of which are discussed briefly in the next section.


There are more excuses (defenses) than are listed here, but contributory negligence or comparative negligence, assumption of risk, and act of God are among the principal defenses that will completely or partially excuse the negligence of the defendant.

Contributory and Comparative Negligence

Under an old common-law rule, it was a complete defense to show that the plaintiff in a negligence suit was himself negligent. Even if the plaintiff was only mildly negligent, most of the fault being chargeable to the defendant, the court would dismiss the suit if the plaintiff’s conduct contributed to his injury. In a few states today, this rule of contributory negligenceActions of a plaintiff that contribute to his or her own injuries. In a few states, comparative negligence is a complete bar to the plaintiff’s recovery. is still in effect. Although referred to as negligence, the rule encompasses a narrower form than that with which the defendant is charged, because the plaintiff’s only error in such cases is in being less careful of himself than he might have been, whereas the defendant is charged with conduct careless toward others. This rule was so manifestly unjust in many cases that most states, either by statute or judicial decision, have changed to some version of comparative negligenceIn most states, the negligence of the plaintiff is weighed against the negligence of the defendant, and where the defendant’s negligence outweighs the plaintiff’s, the plaintiff can recover against the defendant even though the plaintiff has caused some of his or her own injuries.. Under the rule of comparative negligence, damages are apportioned according to the defendant’s degree of culpability. For example, if the plaintiff has sustained a $100,000 injury and is 20 percent responsible, the defendant will be liable for $80,000 in damages.

Assumption of Risk

Risk of injury pervades the modern world, and plaintiffs should not win a lawsuit simply because they took a risk and lost. The law provides, therefore, that when a person knowingly takes a risk, he or she must suffer the consequences.

The assumption of risk doctrine comes up in three ways. The plaintiff may have formally agreed with the defendant before entering a risky situation that he will relieve the defendant of liability should injury occur. (“You can borrow my car if you agree not to sue me if the brakes fail, because they’re worn and I haven’t had a chance to replace them.”) Or the plaintiff may have entered into a relationship with the defendant knowing that the defendant is not in a position to protect him from known risks (the fan who is hit by a line drive in a ballpark). Or the plaintiff may act in the face of a risky situation known in advance to have been created by the defendant’s negligence (failure to leave, while there was an opportunity to do so, such as getting into an automobile when the driver is known to be drunk).

The difficulty in many cases is to determine the dividing line between subjectivity and objectivity. If the plaintiff had no actual knowledge of the risk, he cannot be held to have assumed it. On the other hand, it is easy to claim that you did not appreciate the danger, and the courts will apply an objective standard of community knowledge (a “but you should have known” test) in many situations. When the plaintiff has no real alternative, however, assumption of risk fails as a defense (e.g., a landlord who negligently fails to light the exit to the street cannot claim that his tenants assumed the risk of using it).

At the turn of the century, courts applied assumption of risk in industrial cases to bar relief to workers injured on the job. They were said to assume the risk of dangerous conditions or equipment. This rule has been abolished by workers’ compensation statutes in most states.

Act of God

Technically, the rule that no one is responsible for an “act of God,” or force majeure as it is sometimes called, is not an excuse but a defense premised on a lack of causation. If a force of nature caused the harm, then the defendant was not negligent in the first place. A marina, obligated to look after boats moored at its dock, is not liable if a sudden and fierce storm against which no precaution was possible destroys someone’s vessel. However, if it is foreseeable that harm will flow from a negligent condition triggered by a natural event, then there is liability. For example, a work crew failed to remove residue explosive gas from an oil barge. Lightning hit the barge, exploded the gas, and injured several workmen. The plaintiff recovered damages against the company because the negligence consisted in the failure to guard against any one of a number of chance occurrences that could ignite the gas.Johnson v. Kosmos Portland Cement Co., 64 F.2d 193 (6th Cir. 1933).

Vicarious Liability

Liability for negligent acts does not always end with the one who was negligent. Under certain circumstances, the liability is imputed to others. For example, an employer is responsible for the negligence of his employees if they were acting in the scope of employment. This rule of vicarious liability is often called respondeat superior, meaning that the higher authority must respond to claims brought against one of its agents. Respondeat superior is not limited to the employment relationship but extends to a number of other agency relationships as well.

Legislatures in many states have enacted laws that make people vicariously liable for acts of certain people with whom they have a relationship, though not necessarily one of agency. It is common, for example, for the owner of an automobile to be liable for the negligence of one to whom the owner lends the car. So-called dram shop statutes place liability on bar and tavern owners and others who serve too much alcohol to one who, in an intoxicated state, later causes injury to others. In these situations, although the injurious act of the drinker stemmed from negligence, the one whom the law holds vicariously liable (the bartender) is not himself necessarily negligent—the law is holding him strictly liable, and to this concept we now turn.

Key Takeaway

The most common tort claim is based on the negligence of the defendant. In each negligence claim, the plaintiff must establish by a preponderance of the evidence that (1) the defendant had a duty of due care, (2) the defendant breached that duty, (3) that the breach of duty both actually and approximately has caused harm to the plaintiff, and (4) that the harm is measurable in money damages.

It is also possible for the negligence of one person to be imputed to another, as in the case of respondeat superior, or in the case of someone who loans his automobile to another driver who is negligent and causes injury. There are many excuses (defenses) to claims of negligence, including assumption of risk and comparative negligence. In those few jurisdictions where contributory negligence has not been modified to comparative negligence, plaintiffs whose negligence contributes to their own injuries will be barred from any recovery.


  1. Explain the difference between comparative negligence and contributory negligence.
  2. How is actual cause different from probable cause?
  3. What is an example of assumption of risk?
  4. How does res ipsa loquitur help a plaintiff establish a case of negligence?