Mistake of Fact in Japanese Criminal Law: How Can a Factual Misunderstanding Affect Criminal Liability?

Criminal liability hinges not only on a prohibited act and its unlawfulness but also critically on the actor's state of mind. Intent (故意, koi) generally requires an awareness of the facts that constitute the crime. But what happens when an individual acts with a certain criminal intent, yet there's a discrepancy between the facts as they perceived or foresaw them and the facts as they actually occurred? This is known as a mistake of fact (事実の錯誤, Jijitsu no Sakugo). Japanese criminal law has developed a structured approach, primarily centered on the Legal Congruence Theory (法定符合説, Hōtei Fugō Setsu), to determine how such factual misunderstandings impact the establishment of criminal intent and, consequently, liability for the crime that actually transpired.

The core issue in mistake of fact scenarios is not to punish an individual for a crime they merely thought about, but rather to ascertain whether the intent they possessed can be deemed sufficient for the crime that actually occurred, despite the factual error. It's about defining the minimum scope of awareness and foresight necessary to hold someone accountable for the actual outcome.

The Guiding Principle: Legal Congruence Theory (Hōtei Fugō Setsu)

The dominant approach in Japanese courts and among legal scholars for resolving mistakes of fact is the Legal Congruence Theory. This theory posits that criminal intent for the actually committed offense can be affirmed if the facts as recognized or foreseen by the actor and the facts that actually occurred "coincide" or "match" (符合, fugō) within the scope of a statutory criminal definition (kōsei yōken). In simpler terms, if the essence of what the actor intended to do and what actually happened are legally the same type of crime, the mistake about specific details may not negate intent for the actual crime.

Within this overarching theory, two main variants exist:

1. Abstract Legal Congruence Theory (抽象的法定符合説, Chūshō-teki Hōtei Fugō Setsu): This is the prevailing view. It holds that intent is established if the intended act and the actual act fall under the same abstract statutory definition of a crime. Minor discrepancies in the specific details of how the crime was committed or against whom are often considered irrelevant, as long as the core abstract elements of the intended crime match those of the crime committed. For example, if one intends to "kill a person" and a person is indeed killed, intent for homicide is generally affirmed, even if the specific identity of the person killed or the exact manner of death differed from the initial plan.
2. Concrete Legal Congruence Theory (具体的法定符合説, Gutai-teki Hōtei Fugō Setsu): This is a more restrictive view. It requires a closer congruence between the specifically intended facts and the actually occurring facts. While still operating within the framework of statutory definitions, it places more importance on the concrete object or victim intended.

Mistakes of fact are broadly categorized into "concrete mistakes of fact" (where the intended and actual crimes fall under the same statutory provision) and "abstract mistakes of fact" (where they fall under different provisions).

1. Concrete Mistake of Fact (具体的事実の錯誤, Gutai-teki Jijitsu no Sakugo) – Same Crime, Different Details

A concrete mistake of fact occurs when the actor intends to commit a specific crime, and the crime that actually occurs falls under the very same statutory definition, but there's a mistake regarding the object, the victim, or the causal process.

A. Mistake of Object (客体の錯誤, Kyakutai no Sakugo / Error in Persona)

This occurs when the actor mistakes the identity of the object or person they are targeting. For example, an assailant intends to shoot and kill Person A but, due to misidentification, shoots and kills Person B, believing B to be A.

• Under the Abstract Legal Congruence Theory, intent for the murder of B is generally affirmed. The reasoning is that the actor intended to "kill a person" (the abstract element of homicide), and they did, in fact, "kill a person" (B). The specific identity of the person is considered legally irrelevant for the purpose of establishing intent for homicide. A Daishin-in (Great Court of Cassation) ruling of February 4, 1922, supports this line of reasoning.
• The Concrete Legal Congruence Theory might also affirm intent for killing B, but often on a slightly different basis: the actor aimed at the "person before them" (who happened to be B), albeit under the mistaken belief that this person was A. The concrete intent to kill the physically present individual is seen as sufficient.

Thus, in most cases of mistake of object within the same crime category, Japanese law will find the requisite intent for the crime actually committed.

B. Mistake in the Method/Strike (方法の錯誤, Hōhō no Sakugo / 打撃の錯誤, Dageki no Sakugo / Aberratio Ictus)

This type of mistake arises when the actor correctly identifies their target but, due to an error in the execution of their act, harms a different object or person. For instance, the actor shoots at Person A but misses, and the bullet strikes and kills Person B instead.

• This is where the Abstract and Concrete Legal Congruence Theories most clearly diverge.
  • The Abstract Legal Congruence Theory generally affirms intent for the killing of Person B. The logic remains that the actor intended to "kill a person," and a person (B) was indeed killed as a direct result of that criminal enterprise. The misdirection of the attack does not negate the fundamental intent to commit homicide. The Supreme Court ruling of July 28, 1978, where an assailant intending to kill A injured A but also injured B with the same attack, affirmed intent for the injury to B, reflecting this approach.
  • The Concrete Legal Congruence Theory, on the other hand, would typically negate intent for the killing of B, because B was not the specific person targeted. Under this view, the actor would be liable for an attempted crime against A and, potentially, for negligent homicide or injury concerning B (if negligence can be established).
• The prevailing judicial practice in Japan aligns with the Abstract Legal Congruence Theory, thus tending to affirm intent for the unintended victim in aberratio ictus scenarios if the harm is of the same legal type as intended.

C. Mistake as to Causation (因果関係の錯誤, Inga Kankei no Sakugo)

This occurs when the actor achieves the intended result against the intended object or victim, but the causal process unfolds differently from what was envisioned. For example, A intends to poison B, but B, after ingesting a non-fatal dose, stumbles and dies from a fall induced by the initial effects of the poison, rather than from the poison's direct toxicity as planned by A.

• Generally, under both variants of the Legal Congruence Theory, if the deviation in the causal process is not so fundamental as to sever the legal link between the act and the result (i.e., if the "realization of danger" from the initial act can still be established for the actual result), intent is usually upheld. Minor or foreseeable deviations in how the result comes about do not negate intent.
• Special Cases within Causal Mistakes:
  • "Weber's General Intent" Cases (Mistaken Sequence): This classic scenario involves a two-act situation where the actor believes the intended result was achieved by their first act, but it was actually brought about by a second, subsequent act. For example, an actor strangles a victim (Act 1) and, mistakenly believing the victim to be dead, disposes of the body by throwing it into a river (Act 2), where the victim then drowns. A Daishin-in ruling of April 30, 1923, addressed such a situation. Courts often find intent for the completed crime (e.g., homicide) if the entire sequence of events can be viewed as a single transaction driven by the initial criminal intent, or if the initial act is causally linked to the final result, even through the unintended mechanism of the second act. The focus is on whether the actor's initial criminal plan and danger creation ultimately led to the intended type of harm.
  • Premature Realization of Elements (早すぎた構成要件の実現, Hayasugita Kōsei Yōken no Jitsugen): This is the inverse scenario. The actor intends to achieve the criminal result through a later act (Act 2) but inadvertently achieves it through an earlier preparatory or initial act (Act 1). For example, A intends to render B unconscious with chloroform (Act 1) and then drown B (Act 2), but B dies from the chloroform application itself. A Supreme Court ruling of March 22, 2004, dealt with such facts. If Act 1 already possessed the objective danger necessary to constitute a criminal attempt (e.g., attempted murder), and the intended type of result (death) ensues from it, intent for the completed crime is generally affirmed. The mistake about which of the planned acts would be fatal is considered a non-essential deviation in the causal process.

2. Abstract Mistake of Fact (抽象的事実の錯誤, Chūshō-teki Jijitsu no Sakugo) – Different Crimes Intended vs. Committed

An abstract mistake of fact arises when the crime the actor intended to commit and the crime that actually occurs fall under different statutory provisions (i.e., they have different constituent elements or kōsei yōken). For example, intending to cause property damage (e.g., by setting a small fire) but actually causing an occupied dwelling to burn (arson of an inhabited structure, a much graver offense).

A. Penal Code Article 38, Paragraph 2

The Japanese Penal Code, in Article 38, Paragraph 2, provides a specific rule: "A person who, when committing an act that is to constitute a grave crime, did not know at the time of the act that it was to constitute such grave crime, shall not be punished for the grave crime." This directly addresses situations where the actor was unaware of facts that would make their conduct a more serious offense than they envisioned. They would instead be punished for the less serious crime they intended (if its elements are met by their actions and the actual result).

B. The Role of "Substantive Overlap" (実質的重なり合い, Jisshitsuteki Kasanariai)

Beyond the specific provision of Article 38(2), the Abstract Legal Congruence Theory resolves abstract mistakes of fact by looking for a "substantive overlap" or "commonality" between the constituent elements of the crime intended and the crime actually committed.

• If a Substantive Overlap Exists: Intent can be affirmed for the crime that corresponds to this common, overlapping part.
  • Actual Crime is Less Grave than Intended Crime: If A intends to commit Crime X (e.g., robbery) but actually commits only the elements of Crime Y (e.g., assault or theft, which are components of robbery), A is liable for Crime Y (or an attempt of X if Y is seen as part of that attempt). The intent for the more serious crime includes the intent for its less grave components.
  • Actual Crime is More Grave than Intended Crime (and Art. 38(2) applies): As stated by Article 38(2), if A intends Crime Y (less grave) but their act fulfills the elements of Crime X (more grave) due to facts unknown to A, A cannot be punished for the graver Crime X. However, A can still be punished for Crime Y, if the elements of Crime Y are encompassed within the facts of Crime X. Liability is found for the intended (or overlapping less grave) crime.
  • Crimes of Roughly Equal Gravity with Overlap: The Supreme Court ruling of March 27, 1979, is instructive. The defendant intended to import amphetamines (at the time, a restricted substance under one law) but actually imported heroin (a prohibited substance under a different narcotics law). The Court found that, despite being regulated by different statutes, the societal harm, nature of the acts, and the prescribed penalties were very similar, indicating a "substantive overlap." It affirmed conviction for the actual crime committed (heroin importation), effectively finding that the defendant's intent to import one type of illicit drug could found the intent for importing another of a similar illicit nature and gravity. A similar approach was taken in a Supreme Court ruling of June 9, 1986, concerning possession of different types of controlled substances where intent was affirmed for the lesser intended offense when a graver one was actually committed, based on the overlap.
• Determining "Substantive Overlap": This is a key analytical step and often involves comparing:
  • The legal interests protected by the respective statutes (保護法益, hogo hōeki).
  • The core nature of the prohibited conduct.
  • The prescribed penalties (as an indicator of perceived gravity).
    If these aspects are fundamentally different (e.g., intending minor property damage but causing an unintended homicide), there's no substantive overlap, and intent for the distinct, unintended crime cannot be established. The actor might be liable for an attempt of the crime they intended (if applicable) and separately for negligence concerning the crime they actually committed (if negligence for that crime is punishable).

3. Practical Implications in Business and Corporate Settings

Mistakes of fact can arise in complex business operations and potentially impact criminal liability:

• Misidentification of Assets or Counterparties: In transactions involving regulated goods or financial instruments, an employee might mistakenly deal with a prohibited item or an unauthorized counterparty, believing them to be legitimate. If the core intent was, for example, to engage in "a financial transaction" and the actual transaction, though mistaken in its specifics, still falls under a similar type of financial crime, intent might be affirmed under abstract legal congruence for the actual offense (or a related, overlapping lesser offense).
• Errors in Understanding the Nature of Information: An employee might handle sensitive data believing it to be general business information when, in fact, it constitutes legally protected personal information or a trade secret. If they disclose it with an intent that covers the general act of disclosure, but are mistaken about its specific protected status, this could lead to complex questions of intent for offenses like breach of data privacy or misappropriation of trade secrets.
• Complex Regulatory Environments: Businesses operate under numerous, often intricate, regulations. An employee might intend to comply with one set of rules but, through a factual misunderstanding (e.g., about the chemical composition of a substance, the origin of goods, or the status of a permit), inadvertently violate another, potentially more serious, regulation. The analysis of "substantive overlap" would be crucial in determining liability.
• Internal Investigations: When investigating potential wrongdoing within a company, it's vital to ascertain not just what happened, but also what the involved individuals knew and intended. A mistake of fact can be a crucial defense or a significant mitigating factor.

Conclusion

Japanese criminal law's approach to mistake of fact, primarily through the lens of the Abstract Legal Congruence Theory, seeks to strike a balance. It aims to hold individuals accountable for the general nature of the criminal wrongdoing they set out to achieve, even if specific details go awry. However, it also respects the principle that intent must be established for the core elements of the crime actually committed. For concrete mistakes, intent is often found for the actual result if it's of the same legal type as intended. For abstract mistakes, the concept of "substantive overlap" between the intended and actual offenses plays a critical role in determining the scope of liability, often resulting in conviction for the less grave of the offenses involved or for the crime corresponding to the common elements. This nuanced framework highlights the importance of a clear understanding of factual circumstances in any activity that might carry criminal law implications.