Principals in the Shadows: How Japan's Supreme Court Holds Conspirators Fully Liable for a Crime
If a group of people plots a murder, but only a few of them carry out the actual killing, are the planners sitting miles away as guilty as those who wield the weapons? Can a person be a principal perpetrator of a crime they never physically touched? On May 28, 1958, the Grand Bench of the Supreme Court of Japan answered these fundamental questions with a resounding "yes" in one of the most important rulings in modern Japanese criminal law. Known as the "Nerima Case," this decision formally established the doctrine of "conspiracy as co-perpetration" (共謀共同正犯 - kyōbō kyōdō seihan), providing a powerful legal framework for holding all members of a criminal plot fully responsible for its outcome.
The Facts: A Labor Dispute Turns Deadly
The case arose from a bitter and violent labor dispute at a factory in Nerima, Tokyo, in the winter of 1951. Two rival unions were locked in conflict. Tensions escalated dramatically after members of the first union were arrested for allegedly assaulting members of the second, leading to intense animosity toward the rival union's leader, V, and a local police officer, W.
This resentment boiled over into a coordinated criminal plot. A group of ten men, defendants A through J, all members or supporters of the first union, decided to take revenge by physically assaulting both V and W.
The conspiracy was not a single event but a series of interconnected meetings. Defendants A and B first met with another individual to plan the assaults, with B taking a lead role in coordination. On the night of the crime, a larger group including B met to finalize the plan to attack officer W. Meanwhile, another subset of the conspirators met separately to plan the attack on the union leader V. When they were unable to locate V, they decided to join forces with the first group to carry out the assault on W.
That night, a number of the conspirators, including defendants C, D, E, F, G, I, and J, went to the scene. They lured officer W out of his police box by falsely reporting that a person had collapsed in the street. When W came to investigate, they ambushed him, beating him mercilessly with iron pipes. Officer W died from his injuries, which included a severe skull fracture and brain damage.
Crucially, two of the original plotters, defendants A and B, were not present at the scene of the crime. Their involvement was limited to the planning and coordination phase.
The Legal Challenge: Can You Be a Principal Perpetrator from Afar?
All ten men were charged as co-perpetrators of Causing Death by Injury. The defense for the absent defendants, A and B, mounted a fundamental challenge to the very idea of "conspiracy as co-perpetration." They argued that holding someone liable as a principal for a crime they did not physically commit violates the core legal principle of individual responsibility. A and B, they contended, were at most accomplices or instigators, not principals who bore full responsibility for the fatal beating.
The Supreme Court's Landmark Definition
The Supreme Court rejected this challenge and upheld the convictions of all ten men, including the absent A and B, as full co-perpetrators. In its historic decision, the Court laid out the definitive three-part test for establishing "conspiracy as co-perpetration," a test that remains the standard in Japan today.
The Court ruled that the doctrine applies when:
- Two or more persons conspire to commit a specific crime.
- This "conspiracy" (謀議 - bōgi) involves a common intent to act as a unified body, with each member agreeing to mutually use the actions of the others to carry out their own criminal will.
- The crime is then executed based on this conspiracy.
Having established this test, the Court delivered its powerful conclusion on liability:
"As long as a person is found to have participated in the conspiracy in such a relationship, even if they did not directly participate in the execution of the act, there is no reason to find a difference in criminal liability, in the sense that they committed the crime by using the actions of others as their own means."
In the Court's view, direct participation in the physical act is irrelevant to one's status as a principal perpetrator. Once you join the conspiracy, you are fully responsible for the actions of your co-conspirators.
A New Theoretical Foundation: From "Group Mind" to "Crime by Instrument"
Legal scholars note that the Nerima Case marked a crucial theoretical shift in Japanese law. While the concept of holding conspirators liable had existed before, it was often justified by a vague theory of a "common intent entity" (共同意思主体説), which treated the group as a single collective actor.
The 1958 decision, however, introduced new and vital language: "using the actions of others as... their own means" (他人の行為をいわば自己の手段として). This phrase provided a new, more solid foundation for the doctrine, grounding it in a theory similar to indirect perpetration (where a person uses an innocent party as an instrument).
Under this new framework, the off-site conspirator is a principal not because they are part of a mystical "group mind," but because they are using the on-site actors as their tools or instruments to achieve their own criminal goal. This brilliantly anchors the doctrine in the very principle the defense had invoked: individual responsibility. You are not responsible for the group's actions; you are responsible for your action of using the group to commit your crime.
The Unanswered Question and Lasting Debate
While the Nerima decision was groundbreaking, legal commentators point out that it left a critical question unanswered. The Court meticulously defined the requirements for liability but never provided a precise definition of the key term at the doctrine's heart: "conspiracy" (kyōbō) itself.
This ambiguity sparked a decades-long academic debate over what constitutes a legally sufficient conspiracy. Does it require an objective, physical meeting and discussion? Or can it be a purely subjective "meeting of the minds" between individuals who have never spoken? While this debate continues, the core principle of the Nerima decision remains unshaken.
Conclusion
The 1958 Nerima Case is one of the most significant decisions in the history of Japanese criminal law. It definitively established that individuals who plot a crime are as guilty as those who carry it out. By grounding this powerful doctrine in the principle of "using others as a means," the Court affirmed that there is no legal distinction between the hand that wields the weapon and the mind that commanded it as part of a common criminal enterprise. In the eyes of the law, those who conspire in the shadows are principals, and they bear full responsibility for the outcome.