Proximate cause

Other factors

There are several competing theories of proximate cause.

Foreseeability

The most common test of proximate cause under the American legal system is foreseeability. It determines if the harm resulting from an action could reasonably have been predicted. The test is used in most cases only in respect to the type of harm. It is foreseeable, for example, that throwing a baseball at someone could cause them a blunt-force injury. But proximate cause is still met if a thrown baseball misses the target and knocks a heavy object off a shelf behind them, which causes a blunt-force injury.

This is also known as the "extraordinary in hindsight" rule.

In the United Kingdom, a "threefold test" of foreseeability of damage, proximity of relationship and reasonableness was established in the case of Caparo v Dickman (1990) and adopted in the litigation between Lungowe and others and Vedanta Resources plc (Supreme Court ruling 2019).

Direct causation

Direct causation is a minority test, which addresses only the metaphysical concept of causation. It does not matter how foreseeable the result as long as what the negligent party's physical activity can be tied to what actually happened. The main thrust of direct causation is that there are no intervening causes between an act and the resulting harm. An intervening cause has several requirements: it must 1) be independent of the original act, 2) be a voluntary human act or an abnormal natural event, and 3) occur in time between the original act and the harm.

Direct causation is the only theory that addresses only causation and does not take into account the culpability of the original actor.

Risk enhancement/causal link

The plaintiff must demonstrate that the defendant's action increased the risk that the particular harm suffered by the plaintiff would occur. If the action were repeated, the likelihood of the harm would correspondingly increase. This is also called foreseeable risk.

Harm within the risk

The harm within the risk (HWR) test determines whether the victim was among the class of persons who could foreseeably be harmed, and whether the harm was foreseeable within the class of risks. It is the strictest test of causation, made famous by Benjamin Cardozo in Palsgraf v. Long Island Railroad Co. case under New York state law.

The first element of the test is met if the injured person was a member of a class of people who could be expected to be put at risk of injury by the action. For example, a pedestrian, as an expected user of sidewalks, is among the class of people put at risk by driving on a sidewalk, whereas a driver who is distracted by another driver driving on the sidewalk, and consequently crashes into a utility pole, is not.

The HWR test is no longer much used, outside of New York law. When it is used, it is used to consider the class of people injured, not the type of harm. The main criticism of this test is that it is preeminently concerned with culpability, rather than actual causation.

The "Risk Rule"

Referred to by the Reporters of the Second and Third Restatements of the Law of Torts as the "scope-of-the-risk" test, the term "Risk Rule" was coined by the University of Texas School of Law's Dean Robert Keeton. The rule is that “[a]n actor’s liability is limited to those physical harms that result from the risks that made the actor’s conduct tortious.” Thus, the operative question is "what were the particular risks that made an actor's conduct negligent?" If the injury suffered is not the result of one of those risks, there can be no recovery. Two examples will illustrate this principle:

• The classic example is that of a father who gives his child a loaded gun, which she carelessly drops upon the plaintiff's foot, causing injury. The plaintiff argues that it is negligent to give a child a loaded gun and that such negligence caused the injury, but this argument fails, for the injury did not result from the risk that made the conduct negligent. The risk that made the conduct negligent was the risk of the child accidentally firing the gun; the harm suffered could just as easily have resulted from handing the child an unloaded gun.
• Another example familiar to law students is that of the restaurant owner who stores rat poison above the grill in his luncheonette. The story is that during the lunch rush, the can explodes, severely injuring the chef who is preparing food in the kitchen. The chef sues the owner for negligence. The chef may not recover. Storing rat poison above the grill was negligent because it involved the risk that the chef might inadvertently mistake it for a spice and use it as an ingredient in a recipe. The explosion of the container and subsequent injury to the chef was not what made the chosen storage space risky.

The notion is that it must be the risk associated with the negligence of the conduct that results in an injury, not some other risk invited by aspects of the conduct that in of themselves would not be negligent.

Controversy

The doctrine of proximate cause is notoriously confusing. The doctrine is phrased in the language of causation, but in most of the cases in which proximate cause is actively litigated, there is not much real dispute that the defendant but-for caused the plaintiff's injury. The doctrine is actually used by judges in a somewhat arbitrary fashion to limit the scope of the defendant's liability to a subset of the total class of potential plaintiffs who may have suffered some harm from the defendant's actions.

For example, in the two famous Kinsman Transit cases from the 2nd Circuit (exercising admiralty jurisdiction over a New York incident), it was clear that mooring a boat improperly could lead to the risk of that boat drifting away and crashing into another boat, and that both boats could crash into a bridge, which collapsed and blocked the river, and in turn, the wreckage could flood the land adjacent to the river, as well as prevent any traffic from traversing the river until it had been cleared. But under proximate cause, the property owners adjacent to the river could sue (Kinsman I), but not the owners of the boats or cargoes which could not move until the river was reopened (Kinsman II).

Therefore, in the final version of the Restatement (Third), Torts: Liability for Physical and Emotional Harm, published in 2010, the American Law Institute argued that proximate cause should be replaced with scope of liability. Chapter 6 of the Restatement is titled "Scope of Liability (Proximate Cause)." It begins with a special note explaining the institute's decision to reframe the concept in terms of "scope of liability" because it does not involve true causation, and to also include "proximate cause" in the chapter title in parentheses to help judges and lawyers understand the connection between the old and new terminology. The Institute added that it "fervently hopes" the parenthetical will be unnecessary in a future fourth Restatement of Torts.

Efficient proximate cause

A related doctrine is the insurance law doctrine of efficient proximate cause. Under this rule, in order to determine whether a loss resulted from a cause covered under an insurance policy, a court looks for the predominant cause which sets into motion the chain of events producing the loss, which may not necessarily be the last event that immediately preceded the loss. Many insurers have attempted to contract around efficient proximate cause through the use of "anti-concurrent causation" (ACC) clauses, under which if a covered cause and a noncovered cause join to cause a loss, the loss is not covered.

ACC clauses frequently come into play in jurisdictions where property insurance does not normally include flood insurance and expressly excludes coverage for floods. The classic example of how ACC clauses work is where a hurricane hits a building with wind and flood hazards at the same time. If the evidence later shows that the wind blew off a building's roof and then water damage resulted only because there was no roof to prevent rain from entering, there would be coverage, but if the building was simultaneously flooded (i.e., because the rain caused a nearby body of water to rise or simply overwhelmed local sewers), an ACC clause would completely block coverage for the entire loss (even if the building owner could otherwise attribute damage to wind v. flood).

A minority of jurisdictions have ruled ACC clauses to be unenforceable as against public policy, but they are generally enforceable in the majority of jurisdictions.