Essential Elements of the Tort of Negligence

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The field of negligence is delineated by considerations of whether it is appropriate, or fair, for a duty of care to be imposed. Modern courts have worked to define and elaborate this duty. In so doing, they have sought to define and describe the essential aspects of the duty of care. This article examines the features of the tort of negligence, and the tests and rules that have developed and refined the tort, by applying them to a hypothetical scenario involving an automobile accident.


Any honest person will readily admit to acting negligently from time to time. We don’t floss as often as we know we should. We don’t consume enough green vegetables. We don’t always check the tires before we drive across town. Inadequate dental hygiene and poor eating habits are unlikely to harm anyone but ourselves. A chronically under-inflated tire, however, will be at risk of blowing out, with potentially disastrous—and tortious—results. Because one knows that a worn tire may blow out, and that one may lose control of a vehicle with a blown tire, and that an uncontrollable vehicle can cause serious injury and property damage—because these consequences are readily foreseeable—one will be in breach of one’s duty of care to others if one drives on a worn tire. If I do in fact injure a pedestrian or damage a storefront because I had failed to maintain my vehicle, this negligence will be the factual cause of the damages arising from this failure. And because the risk of these types of damages are obvious and predictable, this negligence could not be considered too remote, but rather would be considered a cause in law. This is a simple or straightforward scenario (especially as it ignores the role of insurers) which contains the three ‘ingredients’ of negligence: 1) the harm is foreseeable; 2) the pedestrian and storefront are proximate; and 3) it is ‘fair, just and reasonable’ to impose a duty of care on me, the negligent operator of the unsafe vehicle.

The analysis of an action for negligence typically begins with the ‘but for’ test. The test poses an either-or question: would the injury not have happened ‘but for’ the negligent act or omission? If the same injury would have occurred even without the defendant’s negligence, then that negligence is not a ‘necessary cause’ of the damage or loss to the claimant. In the scenario described above, my negligence vis automobile maintenance would be a necessary cause of the damage which resulted from the vehicle crashing into the shop: but for the breach, the façade would look as it did before it was rammed by my car.

There are cases, however, where an either-or approach will not allow for a fair outcome. Where there is more than one potential cause of the loss, other approaches are adopted. Where a worker is exposed to a toxin over a number of years at more than one place of employment, for example, and the worker contracts a disease known to be caused by exposure to the toxin, it would be inappropriate (or unfair) for any one employer to be held solely responsible for the harm. For such cases, courts have developed the ‘material contribution to damage’ test for factual cause. With this test, it is not necessary to show that any one breach caused the disease; this would be impossible, in any event. Instead, it is necessary only to show that a particular breach contributed to the harm. The quantum of damages for each defendant would be proportionate to factors such as levels and duration of exposure to the toxin.

There are other types of cases where the application of the ‘but for’ test has been considered inappropriate or unfair. Some have argued that ‘quasi-indeterministic’ cases are appropriately dealt with through a ‘loss of chance’ analysis. An event is quasi-indeterministic if it is not humanly possible to predict it. To paraphrase, where a fact is unknowable, it is unfair to ask a claimant to prove it. Thus far, courts have been largely unwilling to use an ‘opportunity lost’ test for claims of this type; however, it can be argued that it is unjust (i.e. unfair) to employ an ‘all or nothing’ approach when it could not be known how a patient would have fared had he not lost the opportunity of prompt medical treatment, for example. For a negligent act to be considered a cause at law, a ‘chain of causation’ must be shown. To return to the scenario above, the causation may be described as follows:

• I fail to replace the tires on my car.
• As a result, the tires become worn out.
• As a result, a tire blows out as I am driving through town.
• As a result, I lose control of the car.
• As a result, the car crashes into a storefront.
• As a result, the building is damaged.

I am therefore liable for the foreseeable losses which arise such as the cost of repairing the structure and lost custom if the shop closes for a time. But what if some angry neighbour had stealthily placed a tack under the tire before I drove off? This would be a deliberate intervening act or novus actus interveniens which ‘broke’ the chain of causation. The tire would not have blown out and no damage would have occurred except for this act by a third party. True, the operator of a motor vehicle should make a careful inspection of his or her vehicle before operating it, but it was probably not reasonably foreseeable that some fool would place a tack under a tire. In this case my neighbour is solely liable. Now what if the tack punctured the tire only because I had allowed the rubber to become worn down? Would it be fair to release me from liability? This is much less clear, and it would be arguable that the malicious placement of the tack only added to the damage suffered. Finally, what if the vehicle was nearly under control by the time it struck the shop, and only bumped into the façade lightly, but because the façade was poorly constructed it came tumbling down onto the vehicle? Would it be fair then to hold the driver fully liable in this scenario? Or would the builder be liable, and the driver’s (or neighbour’s) negligence be considered the intervening act(s)? On a broad causal approach, the relevant distinction to be drawn would be between ‘normal’ and ‘abnormal’ interventions. In this last scenario, the more ‘abnormal’ intervention is likely that of the neighbour, and finding him responsible (or more responsible) would likely allow the fairest outcome for the defendants.

Not all damages caused by an act of negligence are caused in law. Some damages are simply too remote, or insufficiently proximal. If the person who above the shop was startled awake at the sound of the crash, and then had difficulty getting back to sleep, and as a result slept through his alarm, and then missed a job interview, and so failed to get the job, it would be unfair for him to bring a claim for damages for lost wages. Wages lost, for a job he had not yet secured, would not be considered reasonably foreseeable. There are (arguably) three versions of the remoteness question.

1) Is the full extent of the damage fairly attributable to the defendant’s breach of duty or other tortious intervention?

According to some authorities, fairness of attribution is interpreted in terms of ‘foreseeability’. In cases of negligence, this is meant to align remoteness with duty of care and breach.

2) Is the damage a direct consequence of the defendant’s breach, or has the chain of causation been broken?

This was the approach endorsed by the Court of Appeal of England and Wales in Re Polemis and Furness Withy & Co Ltd (1921 3 KB 560). It appears to pose a factual question, but since the ‘chain of causation’ is not a real entity, it was never anything more than a metaphor.

3) Even if the defendant’s breach is a condition of the damage suffered, so that it satisfies the ‘but for’ test, is it a ‘cause’ of that damage?

This can be seen within the broad ‘common sense causal approach’.

Other rules which courts consider relate to ‘eggshell skull’ and ‘similar in type.’ The ‘eggshell rule’ is often expressed through the saying, “a defendant must take his victim as he finds him.” Returning again to our scenario where the shop was poorly built, it would not matter that the pre-existing condition of the structure worsened the harm caused by the vehicle striking it. If the defendant driver is found liable then under this rule he is liable for the full extent of the damage his negligence caused. This may appear quite unfair to the driver, as it is extremely unlikely that he was involved in the construction of the store. The ‘similar in type’ rule may be described as the principle that the type of damage must be a foreseeable consequence of the negligent act or omission. If the person who lived above the shop suffered a heart attack as a result of the shock of the crash into the building, it would be fair to consider this similar in type, or to be expected (though an insurer would argue otherwise). If he was only awakened and had difficulty sleeping afterward, and then missed a job interview in the morning, the consequences (while unfortunate) could not be considered similar in type.

This article has examined the elements which modern courts consider essential to the tort of negligence. First it looked at the duty of care and the two types of causal analysis: causation in fact and causation in law. The article then examined tests for causes in fact: the ‘but for’ test, the ‘material contribution’ test and the ‘loss of chance’ test. It then moved to an analysis of novus actus interveniens or intervening acts. Finally, it discussed the tests for remoteness, or cause in law, with brief looks at the ‘eggshell skull’ and ‘similar in type’ principles. Negligence generates a great sea of complex case law, and navigating it can be a challenge. Familiarity with its fundamentals allows for smoother sailing.

If you have been harmed as a result of someone's negligence, a paralegal can help. If you are in the Chatham-Kent area, get in touch for a free consultation.