Complicity in Japanese Criminal Law: Understanding Liability as an Accomplice or Joint Principal

Criminal offenses are not always the work of a single individual. Often, multiple parties are involved in planning, instigating, executing, or assisting in the commission of a crime. Japanese criminal law provides a detailed framework for attributing responsibility in such scenarios through its doctrines of complicity (共犯, Kyōhan). This framework distinguishes between those who are deemed principals in the crime and those who play supporting roles as accomplices, with significant implications for the scope of their liability and potential punishment. Key forms of complicity include joint principals (共同正犯, Kyōdō Seihan), instigation (教唆, Kyōsa), and aiding and abetting (幇助, Hōjo or 従犯, Jūhan).

1. The Foundation: Why Punish Complicity?

The rationale for punishing complicity is to ensure that all individuals who contribute to the occurrence of a criminal harm can be held accountable, even if they do not personally carry out every element of the crime as defined by statute (kōsei yōken). Complicity provisions effectively extend the reach of criminal law to capture the broader network of individuals involved in a criminal enterprise. This is often referred to as a "punishment-expanding ground" (処罰拡張事由, shobatsu kakuchō jiyū).

The theoretical basis for punishing accomplices (instigators and aiders) has been a subject of considerable academic discussion. While older theories focused on concepts like shared culpability or shared illegality with the primary offender, a prominent modern view, often termed the Causation-Based Complicity Theory (因果共犯論, Inga Kyōhan Ron or 惹起説, Jakki Setsu), posits that an accomplice is punished because their actions indirectly caused the criminal result (the infringement of a legal interest) by influencing or assisting the principal offender who directly brought it about. From this perspective, the distinction between a sole principal and an accomplice often lies in the directness of their causal contribution to the harm.

2. Joint Principals (共同正犯, Kyōdō Seihan): Acting in Concert

Article 60 of the Japanese Penal Code states: "When two or more persons jointly commit a crime, they are all principals." Joint principals are considered to have primary liability for the crime, on par with a sole perpetrator. Their liability is not merely derivative of another's.

A. The Traditional Model: Joint Execution of the Criminal Act

The classic understanding of joint principalship involved each participant performing a part of the criminal act (jikkō kōi) that constitutes the offense. For example, in a robbery, one person might use force while another takes the property. Each contributes to fulfilling the objective elements of the crime.

B. Joint Principals by Conspiracy (共謀共同正犯, Kyōbō Kyōdō Seihan): The Expanded Scope

A significant development in Japanese criminal law has been the expansion of joint principalship to include those who participate in a conspiracy (共謀, kyōbō) to commit a crime and play an essential role in the criminal enterprise, even if they are not physically present or do not directly perform a part of the actus reus during its execution. This is known as Kyōbō Kyōdō Seihan.

The Supreme Court of Japan has affirmed this doctrine in numerous cases (e.g., Daishin-in ruling of May 28, 1936; Supreme Court ruling of May 28, 1958, the Nerima Case). The key elements for establishing joint principalship by conspiracy are generally understood to be:

1. A Conspiracy: An agreement or mutual understanding among two or more persons to commit a specific crime. This involves a joint criminal intent and an agreement to mutually utilize each other's actions to achieve the common criminal purpose. This conspiracy need not be explicit; an implicit or unspoken understanding can suffice (Supreme Court ruling, May 1, 2003).
2. Execution of the Crime based on the Conspiracy: At least one of the conspirators must actually commence the commission of the agreed-upon crime pursuant to the conspiracy.
3. Essential Contribution by the Conspirator: The individual charged as a joint principal by conspiracy must have made an essential contribution to the formulation or execution of the criminal plan. They are seen as "committing their own crime" by using the joint enterprise and the actions of others as their means.

This doctrine allows for those who mastermind or play a critical organizational role in a crime to be held liable as principals, even if they delegate the actual execution to others.

C. Differing Intents Among Joint Principals

What happens if joint principals have different levels of intent or intend slightly different crimes?

• Partial Crime Co-execution Theory (部分的犯罪共同説, bubun-teki hanzai kyōdō setsu): If their intended crimes overlap in terms of a lesser included offense, they can be held as joint principals for that overlapping lesser crime. For example, if A intends murder and B (acting with A) intends only serious assault, and the victim dies, B might be a joint principal for assault resulting in death, while A is liable for murder (if A's act caused death). The Supreme Court adopted this approach in its ruling of April 13, 1979, where individuals who conspired to commit assault were held liable as joint principals for assault resulting in death when one member, with an intent that went beyond the others', killed the victim. A similar approach was seen in a Supreme Court ruling on July 4, 2005.

3. Instigation (教唆, Kyōsa): Inducing Another to Commit a Crime

Article 61, Paragraph 1 of the Penal Code provides: "A person who instigates another to commit a crime shall be dealt with as a principal." This means an instigator (教唆者, kyōsasha) is subject to the same range of punishment as the person who actually commits the crime (the principal or 正犯, seihan).

Instigation involves:

1. Creating the Criminal Intent: The instigator must cause a person who previously had no intent to commit a particular crime to form that criminal intent. Merely encouraging someone who already intends to commit a crime would typically be aiding, not instigation.
2. Commission of the Crime by the Instigated Person: The instigated person (the principal) must then actually commit the crime (or at least attempt it, if the attempt is punishable).

The instigator's act must be a cause of the principal's decision to commit the crime. Instigation can also occur indirectly; Article 61, Paragraph 2 punishes a person who instigates an instigator ("indirect instigation").

4. Aiding and Abetting (幇助, Hōjo / 従犯, Jūhan): Assisting the Principal

Article 62, Paragraph 1 of the Penal Code states: "A person who aids a principal offender is an accessory (従犯, jūhan)." Article 63 mandates that the punishment for an accessory "shall be reduced from that of the principal."

Aiding (幇助, hōjo) involves:

1. Facilitating the Principal's Crime: The aider must assist the principal in the commission of their crime. This assistance can be physical (e.g., providing tools, acting as a lookout) or psychological (e.g., giving encouragement or advice that strengthens the principal's resolve).
2. Causation: The aid provided must actually make the principal's commission of the crime easier or more likely. If the "aid" is useless or has no bearing on the crime's commission, liability for aiding does not attach. A Daishin-in ruling of July 9, 1913, established that the aid need not be a "but-for" cause of the crime, but it must have facilitated it.

Unlike joint principalship, which typically requires mutual understanding, unilateral aiding (片面的幇助, henmen-teki hōjo)—where the principal is unaware of the aid being provided—is generally considered possible and punishable if it objectively assists the commission of the crime (Daishin-in ruling, January 22, 1925). Aiding an aider ("indirect aiding") is also punishable (Supreme Court, July 17, 1969), but aiding an instigator generally is not, due to the lack of a specific provision.

5. The Principle of Dependence (従属性, Jūzokusei): Linking Accomplice to Principal

The liability of instigators and aiders (often referred to as "narrow complicity" or kyōgi no kyōhan) is generally considered dependent to some extent on the actions of the principal offender. This is known as the Principle of Dependence (Jūzokusei). Joint principals, being principals themselves, are not subject to this form of dependence.

The prevailing view in Japanese law and scholarship is the Limited Dependence Theory (制限従属性説, Seigen Jūzokusei Setsu). This theory holds that for an instigator or aider to be liable:

1. The principal's act must correspond to a statutory criminal definition (構成要件該当性, kōsei yōken gaitōsei). This means the principal must have at least commenced the commission of the crime (i.e., reached the stage of a punishable attempt).
2. The principal's act must also be unlawful (違法性, ihōsei). If the principal's act is justified (e.g., self-defense), then those who instigated or aided that justified act cannot be criminally liable.

Crucially, under the Limited Dependence Theory, the principal offender does not need to be personally culpable (e.g., they could be insane, a minor under the age of criminal responsibility, or acting under duress that negates their culpability). As long as the principal commits an act that fulfills the elements of a crime and is unlawful, the instigator or aider who culpably (i.e., with intent) contributed to that act can be held liable. This separation of the accomplice's culpability from the principal's culpability is a key feature.

6. Complicity in Business and Corporate Crimes

The doctrines of complicity are highly relevant to crimes committed in a corporate or business setting:

• Conspiracy and Joint Principalship in Corporate Misconduct: Complex financial frauds, environmental crimes, or anti-competitive practices (like price-fixing or bid-rigging, often prosecuted under specific laws such as the Anti-Monopoly Act) frequently involve multiple individuals within a corporation, or across different corporations, acting in concert. The doctrine of Kyōbō Kyōdō Seihan (joint principals by conspiracy) is often used to hold accountable not just those who directly executed the illegal acts but also senior executives or managers who planned, authorized, or played an essential role in the scheme.
• Executive Liability for Instigation or Aiding: A superior who directs a subordinate to perform an illegal act (e.g., falsify records, make a corrupt payment) could be liable as an instigator. An executive who knowingly approves or provides resources for an illegal activity initiated by others could be liable for aiding.
• Professional Aiders: External professionals such as lawyers, accountants, or consultants can face liability for aiding and abetting if they knowingly provide services that materially assist in the commission of a corporate crime (e.g., structuring illegal transactions, concealing illicit funds).
• "Willful Blindness": While not a formally defined category of complicity itself, a manager who is willfully blind to ongoing criminal conduct by subordinates, especially where there is a clear duty to supervise and intervene, might face scrutiny. Depending on the specific facts, this could be interpreted as a form of psychological aiding (by creating an environment where crime is tolerated) or could form the basis for direct supervisory negligence if specific statutes apply.
• Joint Principals in Negligence (Kashitsu-han no Kyōdō Seihan): Japanese law also recognizes the concept of joint principals in crimes of negligence (Supreme Court ruling, January 23, 1953). This can occur, for instance, in workplace accidents where multiple individuals (e.g., managers from different departments) through their collective and interrelated breaches of duties of care contribute to a single harmful outcome.

7. Other Important Issues in Complicity

• Mistake (Sakugo): If an instigator or aider intends for the principal to commit Crime A, but the principal actually commits Crime B:
  • If Crime B is more serious than Crime A, the accomplice is typically liable only for complicity in the lesser Crime A (to the extent its elements were part of the principal's actions) (Supreme Court, July 11, 1950 - the Gotton-shi Case).
  • If Crime B is less serious, the accomplice is generally liable for complicity in the actual (lesser) Crime B.
• Successive Complicity (Shōkei-teki Kyōhan): This involves joining a criminal enterprise that is already in progress. Generally, one is liable only for the part of the crime to which they contributed or for consequences flowing from the point of their joining. Liability for prior acts of co-conspirators is usually not imputed unless the late-joiner specifically adopts or utilizes those prior acts in a way that makes them part of their own essential contribution to a continuing offense. Case law on this is complex and fact-dependent. The Supreme Court, in a ruling on November 6, 2012, showed reluctance to broadly affirm successive complicity for an injury that might have occurred before the defendant's involvement.
• Withdrawal from Complicity (Kyōhan Kankei kara no Ridatsu): It is possible for an individual to withdraw from a conspiracy or an ongoing complicity arrangement and thereby avoid liability for the subsequently committed crime. However, mere mental repudiation is insufficient. Effective withdrawal typically requires timely communication of the withdrawal to co-conspirators and, more importantly, actions that effectively neutralize or negate one's prior contribution to the criminal enterprise, especially if that contribution has created an ongoing danger or provided essential means.

Conclusion

The Japanese Penal Code provides a comprehensive, albeit theoretically nuanced, framework for addressing crimes involving multiple participants. The distinction between principals (including those acting jointly through direct execution or by conspiracy) and accomplices (instigators and aiders) is fundamental. For instigators and aiders, their liability is generally dependent on the commission of an unlawful act fulfilling a criminal definition by a principal, though not necessarily on the principal's personal culpability. The expansive doctrine of joint principalship by conspiracy ensures that those who orchestrate and essentially control a criminal enterprise can be held fully accountable as principals. For businesses and their legal counsel, understanding these varying degrees of participation and the conditions for liability is essential for assessing risks and ensuring compliance, as corporate misconduct often involves the coordinated actions of multiple individuals within and sometimes outside the organization.