Introduction

The doctrine of supervening cause, also referred to as superseding cause, occupies a critical juncture in tort law, particularly within the analysis of proximate causation. It addresses situations where an intervening force or act occurs after a defendant's negligent conduct and contributes to the plaintiff's harm. This article provides a scholarly analysis of the supervening cause doctrine as it applies in United States federal and state jurisdictions. Drawing extensively upon seminal case law and established legal principles, including the Restatement (Second) of Torts, this article will explore the definition, essential elements, and application of supervening cause, its interplay with related concepts such as proximate cause and comparative negligence, and the public policy considerations that shape its contours. The objective is to elucidate how courts distinguish between an intervening act that merely contributes to an injury alongside the original negligence and one that is so potent and independent as to sever the causal chain, thereby relieving the initial tortfeasor of liability.

Defining Supervening Cause

At its core, a supervening cause is an intervening act or force that is deemed legally sufficient to break the causal connection between an initial wrongdoer's negligence and the ultimate injury suffered by a plaintiff. This concept is pivotal in determining the scope of a defendant's liability.

The Restatement (Second) of Torts Framework

Many U.S. jurisdictions look to the Restatement (Second) of Torts for guidance on this doctrine. Section 440 of the Restatement defines a superseding cause as "an act of a third person or other force which by its intervention prevents the actor from being liable for harm to another which his antecedent negligence is a substantial factor in bringing about" (Restatement (Second) of Torts § 440, as cited in CRAIG v. DRISCOLL, 2003; WARTNICK v. MOSS BARNETT, 1992; MORGAN v. PENNSYLVANIA GENERAL INS. CO, 1979). The Supreme Court of Minnesota, in WARTNICK v. MOSS BARNETT (1992), explained that the doctrine recognizes that "although an actor's negligent actions may have put the plaintiff in the position to be injured, and therefore contributed to the injury, the actual injury may have been caused by an intervening event. That intervention prevents the original negligent actor from being liable for the final injury."

Purpose and Effect

The doctrine serves as a crucial demarcation in tort law. As articulated by the Supreme Court of Connecticut in CRAIG v. DRISCOLL (2003), "If the third person's negligence is determined to be a superseding cause of the plaintiff's injury, that negligence, rather than the negligence of the party attempting to invoke the doctrine of superseding cause, is said to be the sole proximate cause of the injury." The doctrine thus "serves as a device by which one admittedly negligent party can, by identifying another's superseding conduct, exonerate himself from liability by shifting the causation element entirely elsewhere" (CRAIG v. DRISCOLL, 2003). An intervening cause becomes the direct cause of the injury, breaking the causal connection to the defendant's alleged negligence (CONTROL TECHNIQUES, INC. v. JOHNSON, 2002).

Elements and Application of Supervening Cause

Several factors are critical in determining whether an intervening act qualifies as a supervening cause. Among these, foreseeability is paramount, alongside the independence and nature of the intervening act.

Foreseeability of the Intervening Act

A cornerstone of supervening cause analysis is the foreseeability of the intervening act. Generally, if an intervening act is foreseeable, it will not break the chain of causation and relieve the original tortfeasor of liability. Conversely, an unforeseeable intervening act is more likely to be deemed superseding. The Court of Appeals of New York in DERDIARIAN v. FELIX CONTR CO (1980) emphasized that an intervening act must be "extraordinary or unforeseeable" to sever the causal link. In that case, a driver's epileptic seizure was an intervening act, but it was not considered so unforeseeable as to absolve the contractor whose inadequate safety measures created a foreseeable risk of vehicular accidents at a construction site. The court noted that "the exact manner of an accident need not be foreseeable, only the type of harm."

This principle is echoed in other jurisdictions. The Supreme Court of Alabama stated, "[A]n [act] is superseding only if it is unforeseeable. A foreseeable intervening [act] does not break the causal relationship between the defendants' actions and the plaintiffs' injuries" (S.B. v. ST. JAMES SCHOOL, 2006). Similarly, Ohio law, as discussed in ALLEN E. ADAMS v. LIFT-A-LOFT, CORPORATION (1999), citing Cascone v. Herb Kay Co., holds that "only an intervening act that was unforeseeable was sufficient to break the chain of causation," and the foreseeability of an employer's intervening negligence was a genuine issue for the jury. Indiana law also provides that if a defendant "could have reasonably foreseen the actions of the third party or agency, then the defendant can still be liable" (CONTROL TECHNIQUES, INC. v. JOHNSON, 2002). However, where injuries are "unforeseeable and completely attenuated from the alleged negligence," liability may not attach, as found in HENNIGAN v. JOHNSON (1997), where the plaintiff's act of kicking her way out of a camper and breaking her leg was deemed unforeseeable.

Independence and Nature of the Intervening Act

For an act to be superseding, it must typically be a "new or independent cause" (S.B. v. ST. JAMES SCHOOL, 2006). If the defendant's negligence created or increased the foreseeable risk of harm through the intervention of another force, and the defendant's negligence itself is a substantial factor in causing the harm, then "such intervention of any nature whatsoever is not a superseding cause" (VEGA BY MUNIZ v. PIEDILATO, 1998, quoting Speiser, The American Law of Torts).

The intervening act is often that of a third party (CRAIG v. DRISCOLL, 2003; MORGAN v. PENNSYLVANIA GENERAL INS. CO, 1979; CONTROL TECHNIQUES, INC. v. JOHNSON, 2002). For instance, in GRAHAM v. KEUCHEL (1993), the Oklahoma Supreme Court discussed scenarios where the negligence of a third-party driver was held to be the supervening cause of injuries, despite the defendant's antecedent negligence in parking a vehicle, because the defendant's vehicle was clearly visible and the third party had sufficient warning. In a unique context, WARTNICK v. MOSS BARNETT (1992) involved an argument that a legislative enactment creating a new cause of action was a superseding cause, highlighting the diverse nature of acts that might be considered intervening.

Substantial Factor Test

The defendant's antecedent negligence must be a "substantial factor in bringing about the harm" for the issue of supervening cause to arise (CRAIG v. DRISCOLL, 2003). Pennsylvania law, as cited in JENNIFER M. STRAW v. KIRK A. FAIR (2018), similarly frames proximate cause in terms of whether the conduct was "a substantial factor in bringing about the harm." If an intervening act is deemed superseding, it effectively negates the original defendant's conduct as a substantial factor in the eyes of the law for liability purposes.

Relationship with Other Legal Concepts

The doctrine of supervening cause does not exist in a vacuum; it is intricately related to other fundamental tort law concepts.

Proximate Cause

Supervening cause is fundamentally a component of proximate cause analysis. As the Pennsylvania Superior Court noted in JENNIFER M. STRAW v. KIRK A. FAIR (2018), "Proximate cause is a question of law to be determined by a judge and must be established before the question of actual cause can be submitted to a jury." If an intervening act is found to be a superseding cause, it means the defendant's original negligence is no longer considered the proximate, or legal, cause of the plaintiff's injury (DERDIARIAN v. FELIX CONTR CO, 1980; S.B. v. ST. JAMES SCHOOL, 2006). Proximate cause requires a "foreseeable and natural connection between negligence and harm" (DERDIARIAN v. FELIX CONTR CO, 1980). The "elusive nature of proximate cause" was acknowledged in DERDIARIAN, citing PAGAN v. GOLDBERGER.

Plaintiff's Conduct: Contributory and Comparative Negligence

Courts often distinguish between a supervening cause attributable to a third party and the plaintiff's own conduct. The Supreme Court of Wisconsin in MORGAN v. PENNSYLVANIA GENERAL INS. CO (1979) clarified that a "superseding cause is an act by a third party, while the plaintiff's conduct is considered under the umbrella of contributory negligence." This distinction is crucial. The Supreme Court of New Jersey in VEGA BY MUNIZ v. PIEDILATO (1998) suggested that "When the plaintiff's conduct is at issue, the doctrine of comparative negligence is the best framework within which to determine whether the plaintiff's actions preclude his or her recovery in tort," rather than labeling the plaintiff's own negligence as a superseding cause.

However, the interplay can be complex. In STOLT v. GENERAL FOODS CORPORATION (1993), the New York Court of Appeals held that a plaintiff's alleged disobedience of instructions was not a supervening cause of his injuries under Labor Law § 240 (1), as contributory negligence is not a defense to such claims. The Kentucky Court of Appeals in RON CADLE v. ESTATE OF JANE CADLE (2013) discussed the ongoing relevance of the traditional superseding cause doctrine even with the adoption of comparative negligence, noting Kentucky's commitment to "longstanding tort principle that liability based upon negligence is premised upon the traditional prerequisites, such as proximate cause and foreseeability," and expressing skepticism about the Restatement (Third) of Torts' view that comparative negligence diminishes the rationale for superseding cause. The confusion that can arise between contributory negligence and supervening negligence was evident in BOTTARO v. SCHOENBORN (1968), where a jury required further instruction to distinguish the concepts.

Immune Parties and Supervening Cause

An interesting application of supervening cause arises when the intervening actor is immune from suit, such as an employer protected by workers' compensation laws. Delaware law, as established in Duphily v. Delaware Elec. Coop. Inc. (1995) and applied in WELLS v. DELAWARE ELEC. COOP. (2000), permits a defendant to introduce evidence that the negligence of an immune party was the supervening cause of the plaintiff's injury. This allows the defendant to argue that the immune party's actions broke the causal chain, thereby relieving the defendant of liability, even though the immune party cannot be held liable in tort for that negligence (WELLS v. DELAWARE ELEC. COOP., 2000; GENERAL MOTORS CORP. v. WOLHAR, 1996).

Crashworthiness and Specific Defenses

The doctrine has also been applied in specific contexts like crashworthiness litigation. In GENERAL MOTORS CORP. v. WOLHAR (1996), the Supreme Court of Delaware held that evidence of a plaintiff's non-use of a seat belt was admissible to establish that such non-use was the supervening cause of enhanced injuries in an action for negligently defective vehicular design. The court reasoned that preventing a manufacturer from introducing such evidence "would essentially remove the issue of proximate cause in crashworthiness litigation."

Public Policy Considerations

The application of supervening cause is not merely a mechanical exercise; it is also informed by public policy. The Supreme Court of Wisconsin in MORGAN v. PENNSYLVANIA GENERAL INS. CO (1979) outlined several public policy reasons that may preclude liability even where negligence and cause-in-fact are present. These include:

• The injury is too remote from the negligence;
• The injury is too wholly out of proportion to the culpability of the negligent tortfeasor;
• In retrospect, it appears too highly extraordinary that the negligence should have brought about the harm;
• Allowance of recovery would place too unreasonable a burden on the negligent tortfeasor; or
• Allowance of recovery would be too likely to open the way for fraudulent claims.

These considerations, deemed an element of legal cause, are "solely for judicial decision" and reflect the courts' role in drawing lines for liability based on broader societal concerns (MORGAN v. PENNSYLVANIA GENERAL INS. CO, 1979).

Conclusion

The doctrine of supervening cause serves as a critical limiting principle in U.S. tort law, ensuring that liability is not extended indefinitely to actors whose negligence is followed by an independent, unforeseeable, and causally potent intervening act. As demonstrated by the referenced federal and state jurisprudence, the determination of whether an intervening force rises to the level of a supervening cause hinges significantly on the foreseeability of that force, its independence from the original negligent act, and its role as a substantial factor in bringing about the harm. Courts like those in New York (DERDIARIAN v. FELIX CONTR CO, 1980), Connecticut (CRAIG v. DRISCOLL, 2003), and Alabama (S.B. v. ST. JAMES SCHOOL, 2006) consistently emphasize foreseeability, while others, such as in Wisconsin (MORGAN v. PENNSYLVANIA GENERAL INS. CO, 1979) and New Jersey (VEGA BY MUNIZ v. PIEDILATO, 1998), carefully distinguish the plaintiff's own conduct from third-party interventions.

The application of the doctrine is nuanced, often fact-intensive, and reflects an ongoing judicial effort to balance the principle of holding negligent actors accountable with the need to avoid imposing liability for consequences that are too remote or that result from truly independent and extraordinary subsequent events. The interaction of supervening cause with comparative negligence, as highlighted in Kentucky (RON CADLE v. ESTATE OF JANE CADLE, 2013), and its application in specialized areas like crashworthiness (GENERAL MOTORS CORP. v. WOLHAR, 1996 in Delaware) or involving immune parties (WELLS v. DELAWARE ELEC. COOP., 2000 in Delaware), further illustrates the doctrine's dynamic nature. Ultimately, the concept of supervening cause remains an indispensable tool for courts in delineating the scope of legal responsibility in a complex world of multiple contributing factors to injury.