What Exactly Is Being Litigated? Defining the "Subject Matter of Litigation" (Soshobutsu) in Japanese Civil Procedure and Its Impact on Your Case

When a legal dispute enters the courtroom in Japan, one of the most fundamental concepts that shapes the entire proceedings is the "subject matter of litigation," known in Japanese as soshobutsu (訴訟物). This is not merely an academic term; how the soshobutsu is defined and identified has profound practical implications for litigants. It determines the scope of the court's examination, the preclusive effect of the judgment (res judicata), the permissibility of amending claims, and the prohibition against duplicative lawsuits (lis alibi pendens). For any party involved in or contemplating litigation in Japan, a clear understanding of the soshobutsu is essential for effective strategy and case management.

The Theoretical Underpinnings: Old vs. New Theories of Soshobutsu

At its core, the soshobutsu is the specific right or legal relationship for which a party seeks judicial determination. However, Japanese civil procedure scholarship has seen considerable debate over how precisely to conceptualize and identify it. Two main theories have historically vied for prominence:

1. The Old Theory of Soshobutsu (旧訴訟物理論 - kyu-soshobutsu-riron): Also known as the substantive law theory, this view posits that the soshobutsu is identical to the substantive legal right asserted by the plaintiff. For example, if a plaintiff sues for damages based on a breach of contract, the soshobutsu is the specific contractual right to claim those damages. If there are multiple distinct substantive rights (even arising from the same overall incident), they constitute separate soshobutsu.
2. The New Theory of Soshobutsu (新訴訟物理論 - shin-soshobutsu-riron): This procedural law theory takes a broader view, often identifying the soshobutsu based on the societal or economic dispute underlying the claim, or the type of relief sought, rather than strictly adhering to the contours of individual substantive rights. It might, for instance, view all claims arising from a single traffic accident as a single soshobutsu for procedural purposes, even if multiple substantive rights (e.g., property damage, personal injury, psychological distress) are technically involved. The rationale is often to achieve a more comprehensive and unified resolution of the underlying dispute in a single proceeding.

While these theories have generated extensive academic discussion, Japanese court practice has predominantly and consistently favored the Old Theory of Soshobutsu. This means that, in most cases, courts identify the subject matter of litigation by looking at the specific substantive legal right or legal relationship alleged in the "facts constituting the cause of action" (seikyū no gen'in) and the "relief sought" (seikyū no shushi) as stated in the plaintiff's complaint.

The practical consequence of this prevailing approach is that if a plaintiff fails to assert a particular substantive right in their initial claim, a judgment on that claim generally will not preclude a subsequent lawsuit based on a different substantive right, even if both rights arise from the same factual background. This contrasts with broader claim preclusion rules found in some other jurisdictions, such as the "transaction or occurrence" test common in the United States.

Identifying the Soshobutsu in Practice: Criteria and Examples

Given the dominance of the Old Theory, the identification of the soshobutsu hinges on the specific substantive right being asserted. This often involves a careful analysis of the elements required to establish that right under Japanese substantive law (e.g., the Civil Code, Commercial Code).

Single vs. Multiple Soshobutsu from the Same Incident

A key area where the definition of soshobutsu becomes crucial is when multiple types of harm or multiple legal grounds for a claim arise from a single event.

Damages in Tort Cases:
In tort actions, such as those arising from accidents or product liability, a plaintiff may suffer various types_of_damage. The Supreme Court of Japan, in its decision of April 5, 1973 (Minshu Vol. 27, No. 3, p. 419), provided important guidance. It held that when property damage and non-pecuniary damage (e.g., pain and suffering, or慰謝料 - isharyō) arise from the same accident and the same infringement of bodily integrity, they stem from a common factual cause and a common infringed interest. Therefore, the right to claim compensation for both is considered a single soshobutsu. This means that if a plaintiff sues for medical expenses and later tries to sue for pain and suffering from the same physical injury in a separate lawsuit, the second suit would likely be barred by res judicata if the court deems the soshobutsu to be singular and encompassing all damages from that specific infringement.

The Court emphasized that the "infringed interest" (higai rieki) and the "causal facts" (gen'in jijitsu) are key criteria. If these are common, the soshobutsu is generally singular.

Multiple Infringed Rights:
Conversely, if a single act infringes upon multiple, distinct legal rights, these may give rise to separate soshobutsu. For instance, the Supreme Court, in its decision of May 30, 1986 (Minshu Vol. 40, No. 4, p. 725), dealt with a copyright infringement case. It clarified that if an act infringes both the economic rights of a copyright holder (e.g., the right of reproduction) and their moral rights (e.g., the right to integrity), these are considered distinct infringed interests. Consequently, claims for damages based on these separate infringements constitute different soshobutsu, even if they arise from the same infringing act.

Latent Injuries and Subsequent Claims (The "Partial Claim" Approach):
What happens if, after a judgment for damages becomes final, a previously unforeseen consequential injury (e.g., a latent medical condition from an accident) manifests? If the soshobutsu were strictly singular and encompassed all potential harm from the outset, a subsequent claim might be barred. However, the Supreme Court, in a case concerning subsequent claims for after-effects of an injury (decision of July 18, 1967, Minshu Vol. 21, No. 6, p. 1559), adopted a flexible approach, often treating the initial claim as a "partial claim" (ichibu seikyū) with respect to damages that were not reasonably foreseeable or quantifiable at the time of the first litigation. This allows for a subsequent claim for the later-discovered damages, effectively carving out a separate soshobutsu or treating the initial judgment as not having covered these specific, unforeseeable aspects. This approach acknowledges the practical difficulties in predicting all future consequences of an injury.

Soshobutsu and the Principle of Party Disposition (Shobunken Shugi)

The soshobutsu is intimately linked with the principle of party disposition (shobunken shugi), a cornerstone of Japanese civil procedure. This principle, largely enshrined in Article 246 of the Code of Civil Procedure, means that the parties, particularly the plaintiff, control the initiation, scope, and termination of the lawsuit. Article 246 specifically states that a court may not make a judgment on matters not presented by the parties.

This has several implications:

• Defining the Claim: The plaintiff defines the soshobutsu through their complaint, specifying the relief sought and the factual and legal grounds for it.
• Binding the Court: The court is bound by the soshobutsu as defined by the plaintiff. It cannot, for example, award more than what the plaintiff has claimed, nor can it grant relief based on a soshobutsu entirely different from what the plaintiff has asserted.

Judgments for Performance in Exchange (Hikikae Kyūfu Hanketsu)

An interesting intersection of soshobutsu and the principle of party disposition arises in the context of "judgments for performance in exchange" (hikikae kyūfu hanketsu). A common example involves lease disputes. Suppose a lessor sues a lessee for eviction from a property. Under certain circumstances, particularly in residential or commercial leases where tenant protection is a factor, the court might find that the lessor's termination of the lease is only justified if the lessor provides a "relocation payment" or "vacation fee" (tachinoki-ryō) to the lessee. This payment is considered a factor in determining whether the lessor has "just cause" (seitō jiyū) for termination under landlord and tenant law.

The question then arises: if the lessor (plaintiff) sues for eviction without offering any relocation payment, or offers an amount the court deems insufficient, can the court order eviction conditional upon the plaintiff paying a (potentially higher) relocation payment as determined by the court?

The Supreme Court addressed such a scenario in its decision of November 25, 1971 (Minshu Vol. 25, No. 8, p. 1343). In this case, the plaintiff had sought eviction and had offered a certain amount as a relocation payment. The court found that a higher amount was necessary to establish just cause. The Supreme Court upheld the lower court's judgment that ordered eviction in exchange for the plaintiff paying this higher amount. The reasoning often involves a "rational interpretation of the plaintiff's intent." That is, if the plaintiff is seeking eviction and offers some relocation payment, the court may infer that the plaintiff's primary goal is eviction and that they would be willing to pay a reasonably adjusted (even if higher) amount if it's necessary to achieve that goal. The court's power to do this is often seen as a way to achieve a fair and practical resolution, though it pushes the boundaries of a strict interpretation of Article 246.

The soshobutsu in such an eviction case is the lessor's right to demand eviction. The relocation payment is not a separate soshobutsu claimed by the defendant (lessee); rather, it's a condition attached by the court to the plaintiff's primary claim. The court’s ability to modify the amount of this payment is rationalized by interpreting the plaintiff's overall intention to secure eviction, balanced with the legal requirements for just cause, which may include a fair relocation payment. The court will typically engage in clarification (shakumei) with the plaintiff to ascertain their willingness to pay an adjusted amount before issuing such a judgment. If the plaintiff is unwilling, their claim for eviction might simply be dismissed for lack of just cause.

This demonstrates that while the plaintiff defines the soshobutsu, the court, in shaping the final judgment, can introduce conditions or modifications, particularly where substantive law (like tenant protection requiring "just cause" and consideration of relocation payments) intertwines with the procedural claim. The limits of this judicial power in relation to the principle of party disposition are a subject of ongoing academic discussion, focusing on how far the court can go in "interpreting" or "supplementing" the plaintiff's stated claim without overstepping its bounds.

Strategic Implications of Understanding Soshobutsu

A clear grasp of how the soshobutsu is defined in a Japanese context is crucial for several strategic reasons:

• Pleading the Case: Plaintiffs must carefully formulate their claims to ensure all desired substantive rights are included as part of the soshobutsu. Omissions can lead to the inability to pursue those rights later due to res judicata, or necessitate separate, potentially inefficient, lawsuits.
• Scope of Evidence and Argument: The soshobutsu dictates the relevance of evidence and legal arguments. Understanding its boundaries helps focus litigation efforts.
• Assessing Res Judicata: Before initiating a new lawsuit, parties must analyze whether a prior judgment involving similar facts or parties might have a preclusive effect based on the identity of the soshobutsu.
• Settlement Negotiations: The scope of the soshobutsu influences what is being definitively resolved by an in-court settlement, which typically has the same effect as a final judgment on the soshobutsu.
• Considering Amendments: If circumstances change or new aspects of the dispute come to light, understanding the original soshobutsu is vital for determining if and how a claim can be amended.

Conclusion

The concept of soshobutsu, or the subject matter of litigation, is a linchpin of Japanese civil procedure. While the theoretical debates between the Old and New Theories continue to inform academic understanding, the practical reality in Japanese courts is a consistent application of the Old Theory, focusing on the specific substantive legal rights asserted by the plaintiff. This approach has direct consequences for how lawsuits are framed, how judgments are rendered, and the extent to which those judgments preclude future litigation. For businesses and legal professionals navigating disputes in Japan, appreciating the nuances of the soshobutsu is not just an academic exercise but a critical component of effective legal strategy and risk management. The interplay between the soshobutsu and other fundamental principles like party disposition, especially in areas like conditioned judgments, further underscores the need for careful analysis in each specific case.