What Constitutes 'Intent' or 'Negligence' Under Japanese Tort Law?

Under Japan's fault-based tort liability system, enshrined in Article 709 of the Civil Code, establishing that a tortfeasor acted with either "intent" (故意 - koi) or "negligence" (過失 - kashitsu) is a prerequisite for holding them liable for damages. These mental elements, or lack thereof in the case of negligence, are central to the legal analysis. This article explores how Japanese law defines and assesses these crucial concepts.

The principle of requiring fault reflects a balance: while individuals are entitled to freedom of action, this freedom is not absolute and is curtailed when their culpable conduct infringes upon the rights or legally protected interests of others. Understanding the nuances of intent and negligence is therefore vital for anyone involved in or assessing potential tort claims in Japan.

Intent (Koi 故意)

In Japanese tort law, "intent" signifies more than just a deliberate or purposeful act in a colloquial sense. Legal interpretation has focused on two main aspects:

1. The Requisite Level of Volition

A key question is what degree of mental commitment towards the harmful result constitutes "intent." Does it require:

• A positive desire or aim to bring about the result?
• Mere awareness or recognition that the result will (or is likely to) occur?
• Or, something in between, such as an acceptance or condonation (容認 - yōnin) of the result's occurrence, even if not actively desired?

Prevailing thought in Japanese tort law leans towards the third option: "acceptance" or "condonation" of the result is generally sufficient to establish intent. This means the actor, foreseeing the harmful outcome, proceeds with their conduct, thereby accepting the consequence.

2. Dolus Eventualis (Mihitsu no Koi 未必の故意)

A specific form of intent recognized in Japanese law (similar to its application in criminal law) is dolus eventualis, often translated as "conditional intent" or "reckless disregard." This concept applies to situations where:

• The actor does not possess a "definitive intent" (確定的故意 - kakuteiteki koi) – meaning they do not see the harmful result as a certain consequence of their actions, nor do they actively desire it.
• However, the actor recognizes the possibility that their conduct could lead to the harmful result.
• Despite this recognition, they proceed with the conduct, accepting or condoning the potential outcome.

An example often used to illustrate dolus eventualis is a truck driver who, seeing a road densely packed with pedestrians, realizes that driving into the crowd might cause injury but decides to proceed anyway, accepting that such an outcome might occur. This state of mind is generally considered to fall within the scope of "intent" for the purposes of tort liability.

Negligence (Kashitsu 過失)

"Negligence" is perhaps the more commonly encountered basis for tort liability. In everyday language, it might be equated with "fault," "carelessness," "inadvertence," or a "mistake."

Prevailing Legal Definition

The dominant legal definition of negligence in contemporary Japanese tort scholarship is the breach of a duty to take necessary measures to avoid a harmful result (結果回避義務違反 - kekka kaihi gimu ihan), despite the foreseeability of that result (結果発生の予見可能性 - kekka hassei no yoken kanōsei). This definition emphasizes an objective failure to meet a required standard of conduct.

Key Aspects in Assessing Negligence

The assessment of negligence involves several critical considerations:

A. Object of Evaluation (Kashitsu Hyōka no Taishō 過失評価の対象)

What exactly is being evaluated when determining negligence? Historically, there was a tendency to view negligence more subjectively, as a culpable mental state of inattentiveness (an "internal" lack of attention - 内心的注意・不注意). However, modern Japanese tort law has largely shifted towards an objective evaluation of conduct.

The focus is now on whether the actor's external conduct (外的注意・不注意 - gaiteki chūi・fuchūi) in a social context was legally impermissible and careless. Negligence is thus understood as a breach of a socially required duty of conduct or a failure to fulfill a duty to act (行為義務の違反 - kōi gimu no ihan) to prevent harm. This "objectification of negligence" (過失の客観化 - kashitsu no kyakkanka) was notably influenced by landmark precedents such as the Taishin-in (Great Court of Cassation) judgment of December 22, 1916 (Minroku 22-2474), often referred to as the Osaka Alkali case.

The rationale for this objective approach is twofold:

1. Balancing Freedoms and Protections: In a society where individuals interact, their freedoms can collide. The state, while guaranteeing individual liberty, also imposes certain duties of conduct to protect the rights and interests of others. These duties aim to prevent harmful friction and are ideally the minimum necessary to achieve such protection, consistent with constitutional principles. Negligence, then, is a failure to adhere to these objective standards of conduct.
2. The Trust Principle (Shinrai Sekinin 信頼責任): Many scholars also ground the objective view in the "trust principle." This perspective posits that society functions based on a mutual, implicit trust that individuals will generally act in a reasonable and non-harmful manner. A negligent act is thus a breach of this societal trust, failing to meet the behavioral expectations necessary for a well-ordered community.

B. Standard for Judging Negligence (Kashitsu Handan no Kijun 過失の判断基準)

Several criteria are employed to determine if an actor's conduct was negligent:

1. Whose Capacity is the Standard? (誰の能力を基準とするか)
Unlike criminal negligence, which may consider the specific, subjective capacities of the individual actor, civil negligence in Japan is generally judged by an objective standard. The benchmark is the degree of care that a "reasonable person" (合理人 - gōrijin) or a "person exercising the care of a good manager" (善良な管理者の注意 - zenryō na kanrisha no chūi – a traditional Roman law concept) would have exercised in the same circumstances. This is often referred to as "abstract negligence" (抽象的過失 - chūshōteki kashitsu).

However, this "reasonable person" standard is not monolithic. It is relativized and typified based on the group to which the tortfeasor belongs. Factors such as profession, social status, locality, and experience can shape the specific standard of care expected. For example, the standard of care for a medical doctor will vary depending on whether they practice in a cutting-edge university hospital, a regional core hospital, or a small local clinic, as well as their specialty and the prevailing medical environment in their area of practice. The law expects conduct commensurate with the typical capabilities and knowledge of that specific group.

2. At What Point in Time is Capacity Judged? (いつの時点での能力を基準とするか)
The critical moment for assessing negligence is the time of the allegedly tortious act (行為時 - kōiji). The question is: what conduct could have been reasonably expected of the tortfeasor at that specific point in time, given the knowledge and standards then prevailing?

Crucially, scientific or technical knowledge that only became available after the act, or socio-economic conditions that changed subsequently, cannot be used to retroactively establish a duty of care or find negligence. The scope of an individual's freedom of action is determined by what could be reasonably expected of them when they acted. For instance, if a particular medical treatment was not considered standard practice in the year 2000, a doctor cannot be found negligent for not employing it in 2000, even if that treatment became the standard of care by 2015.

This principle also allows for the concept of "phased negligence" (段階的過失 - dankaiteki kashitsu). In a complex incident that unfolds over time (e.g., a period of medical treatment), there might be multiple distinct points or phases where negligence could have occurred. Each phase or decision point would need to be assessed independently for a breach of the duty of care applicable at that specific juncture.

3. Prerequisites for Negligence Assessment: Concrete Danger and Foreseeability (具体的危険、予見可能性)
For an individual to be deemed negligent for breaching a duty of conduct, it must have been reasonable to expect them to act appropriately to avoid the harm. This "expectability" hinges on two key prerequisites:

• Existence of a Concrete Danger (具体的危険 - gutaiteki kiken): There must have been a specific, tangible risk of harm, not just a vague, abstract possibility or a general sense of unease. Some academic debate exists regarding whether, for socially useful but inherently risky activities (like the development of new pharmaceuticals), foreseeability of an abstract danger might suffice, drawing parallels with certain theories in criminal law. However, generally, a more concrete risk is required.
• Foreseeability of that Concrete Danger (予見可能性 - yoken kanōsei): The concrete danger must have been foreseeable to a reasonable person in the actor's position at the time of the act. If a specific danger, although objectively present, was not something a reasonable person would have anticipated, then the basis for finding negligence is typically absent.

In certain types of cases, particularly those involving mass harm from industrial pollution or drug-induced side effects where victims faced immense difficulty in proving that corporations could foresee specific harms, courts developed the concept of a "duty to foresee" (予見義務 - yoken gimu). This doctrine suggests that if a company becomes aware of a potential (even if abstract) danger associated with its activities, it incurs a duty to gather information (情報収集義務 - jōhō shūshū gimu) and conduct necessary research (調査研究義務 - chōsa kenkyū gimu). If the company fails to diligently fulfill this duty, it may be treated as if it had foreseen the concrete dangers that proper investigation would have revealed. Landmark cases such as the Kumamoto Minamata disease litigation (Kumamoto District Court, March 20, 1973, Hanrei Jihō 696-15) and the Tokyo SMON (Subacute Myelo-Optic Neuropathy) litigation (Tokyo District Court, August 3, 1978, Hanrei Jihō 899-48) applied this reasoning, often demanding a very high level of investigation from corporate defendants. However, this "duty to foresee" framework has generally been confined to cases of widespread, severe personal injury resulting from socially useful but hazardous activities, due to concerns about excessively restricting corporate freedom of action if applied too broadly.

4. Factors in Judging Breach of Duty of Conduct (行為義務違反の判断因子)
When determining whether a breach of the duty of conduct (negligence) occurred, courts and scholars sometimes refer to factors similar to those in the "Learned Hand Formula" (B < P x L, where B is the burden of adequate precautions, P is the probability of harm, and L is the gravity of the resulting loss).

The interpretation and weight of these factors, especially the "Burden" (B), can vary:

• Some emphasize economic efficiency, viewing B as the monetary cost of prevention.
• Others advocate for a broader interpretation of B, including not only the tortfeasor's disadvantages but also the social utility or public nature of the conduct in question. The perspective on social utility (e.g., whether it's viewed from a lens of protecting vulnerable parties or promoting economic development) can significantly alter the calculus.
• There are also arguments that the B factor might be inappropriate in certain types of cases, or that the entire formula should be reframed not through an economic lens, but as a tool for balancing constitutionally protected rights (the victim's right to safety versus the tortfeasor's freedom of action) under a proportionality principle.

C. Pleading and Proving Negligence (Kashitsu no Shuchō Risshō Sekinin 過失の主張・立証責任)

It is a common statement that the victim (plaintiff) bears the burden of pleading and proving the tortfeasor's negligence. However, "negligence" itself is a legal conclusion or evaluation made by the judge; it is not a "fact" in the same way that, for example, an action occurring is a fact.

Therefore, what the plaintiff must actually plead and prove are the specific underlying facts that would lead a court to evaluate the defendant's conduct as negligent (過失があったとの評価を根拠づける具体的事実 - kashitsu ga atta to no hyōka o konkodukeru gutaiteki jijitsu). These are the "elemental facts" (要件事実 - yōken jijitsu) that support the legal conclusion of negligence. Each of these specific factual allegations becomes subject to admission or denial by the defendant.

Conversely, the defendant can present, as a defense, specific facts that would hinder or negate an evaluation of negligence (過失があったとの評価を妨げる具体的事実 - kashitsu ga atta to no hyōka o samatageru gutaiteki jijitsu). In this context, negligence is often referred to as a "normative requirement" (規範的要件 - kihanteki yōken) – a legal standard whose satisfaction is determined by evaluating specific proven facts against that standard.

Special Provisions: The Act on Liability for Fire (Shikka Sekinin Hō 失火責任法)

A significant statutory modification to the general principles of negligence concerns liability for accidental fires. The Act on Liability for Fire (明治31年法律第40号), enacted in 1898, provides that Article 709 of the Civil Code (general tort liability) does not apply to damage caused by an accidental fire unless the person who caused the fire was grossly negligent (重大ナル過失 - jūdai naru kashitsu).

This means that if a fire is caused by mere "simple" negligence, the person responsible will typically not be liable for the resulting damage under general tort principles. The victim must prove either intent or gross negligence.

The rationale for this special Act stems from historical and social conditions in Japan at the time of its enactment:

1. The prevalence of wooden houses, which meant fires could easily spread and cause extensive, often catastrophic, damage.
2. The fact that the person who started an accidental fire often suffered significant losses themselves, including the loss of their own property.
   The Act was intended to limit the potentially ruinous liability that could arise from accidental fires caused by simple carelessness.

"Gross negligence" under this Act is interpreted strictly by the courts. The Supreme Court, in a judgment on July 9, 1957 (Minshu 11-7-1203), defined it as "a state of marked lack of attention, almost akin to intent, where the illegal and harmful result could have been easily foreseen with even slight attention, but was nonetheless overlooked." Common examples that might constitute gross negligence include carelessly smoking in bed or leaving a deep-frying pan unattended on a high flame.

The Fire Liability Act's application can become complex in various scenarios, such as fires in leased properties, fires caused by persons lacking legal capacity, or fires caused by employees (where employer liability might also be an issue). In each case, the determination of whose conduct is assessed for gross negligence (the actor, the supervisor, the employer) is a critical point of analysis.

Conclusion

The concepts of "intent" and "negligence" are the lynchpins of Japan's fault-based tort liability system. While "intent" encompasses not only direct desire for a harmful outcome but also the acceptance of a foreseen possibility of such harm (dolus eventualis), "negligence" has evolved into an objective assessment of conduct against a relativized "reasonable person" standard, evaluated at the time of the act. The crucial elements of concrete danger and foreseeability underpin the negligence inquiry, with judicial adaptations like the "duty to foresee" addressing specific societal challenges. The burden of proving facts supporting a finding of negligence generally rests with the victim, though special laws like the Act on Liability for Fire introduce important modifications for specific types of harm. A clear understanding of these principles is essential for navigating the complexities of tort claims under Japanese law.