Defining the "Subject Matter of Litigation" (訴訟物): Why is this Concept Crucial in Japanese Lawsuits?

When a lawsuit is filed in Japan, one of the most fundamental yet conceptually challenging aspects for legal professionals, especially those from different legal traditions, to grasp is the "Subject Matter of Litigation," known as Soshōbutsu (訴訟物). This is not merely a descriptive term for what the lawsuit is "about" in a general sense; rather, it is a precise legal concept that defines the core claim or legal right for which a judicial determination is sought. The identification and definition of the Soshōbutsu have profound implications for various critical stages of a lawsuit, from the initial pleadings to the preclusive effect of the final judgment. Understanding this concept is therefore indispensable for effectively navigating Japanese civil procedure.

I. Defining the "Subject Matter of Litigation" (Soshōbutsu) in Japanese Civil Procedure

A. What is Soshōbutsu?

At its core, the Soshōbutsu is the specific legal claim, right, or legal relationship that the plaintiff requests the court to adjudicate and make a binding pronouncement upon. It is the "object" of the lawsuit, the central issue that the court is asked to resolve. It represents the plaintiff's demand for a particular judicial outcome concerning a defined legal interest.

For instance:

• In a claim for payment of an unpaid invoice, the Soshōbutsu might be defined as "the plaintiff's contractual right to receive JPY X from the defendant based on invoice number Y."
• In an action to confirm ownership of a piece of land, the Soshōbutsu would be "the plaintiff's ownership right concerning parcel Z."
• In an action to annul a shareholders' resolution, the Soshōbutsu is the claim for the judicial invalidation of that specific resolution.

B. Why is Soshōbutsu a Crucial Concept? Its Key Functions

The precise identification of the Soshōbutsu is critically important because it serves several key functions throughout the lifecycle of a lawsuit and beyond:

1. Determining the Scope of Adjudication: The Soshōbutsu defines the boundaries of what the court is required to examine and decide. The court's judgment must address the Soshōbutsu as presented by the plaintiff.
2. Defining the Objective Scope of Res Judicata (Kihan-ryoku 既判力): This is perhaps its most significant function. A final and binding judgment has res judicata effect only with respect to the Soshōbutsu that was adjudicated. This means that the court's determination on the existence or non-existence of that specific Soshōbutsu cannot be re-litigated between the same parties. (Code of Civil Procedure, Art. 114(1)).
3. Guiding Joinder and Amendment of Claims:
   • Joinder of Claims (Uttae no heigō 訴えの併合): Whether multiple claims (multiple Soshōbutsu) can be joined in a single lawsuit depends on rules relating to their connection (Code of Civil Procedure, Art. 136).
   • Amendment of Claims (Uttae no henkō 訴えの変更): Whether a plaintiff can change their claim during the litigation is assessed based on whether the "basis of the claim" (seikyū no kiso 請求の基礎) remains the same, a concept closely related to, though not always identical with, the original Soshōbutsu (Code of Civil Procedure, Art. 143). The theory of Soshōbutsu influences how this "sameness" is evaluated.
4. Basis for Prohibition of Double Litigation (Nijū kiso no kinshi 二重起訴の禁止): A party is prohibited from filing a new lawsuit concerning a Soshōbutsu that is already the subject of a pending action between the same parties in another court (Code of Civil Procedure, Art. 142). Identifying the Soshōbutsu is key to determining if this prohibition applies.
5. Determining Court Fees and Other Procedural Matters: The value of the Soshōbutsu often determines the amount of court fees payable and can influence subject-matter jurisdiction.

II. Theories of Soshōbutsu: Identifying the "Object" of the Lawsuit

How exactly the Soshōbutsu is identified has been a subject of extensive academic debate in Japanese civil procedure, leading to two main theoretical approaches:

A. The "Old" Subject Matter Theory (Substantive Law Theory - 旧訴訟物理論・実体法説 Kyū soshōbutsu riron / Jittai-hō setsu)

• Core Idea: This theory, historically influential, views the Soshōbutsu as the specific substantive legal right itself that the plaintiff asserts (e.g., a particular contractual right to payment under a specific contract, a tort claim for damages arising from a specific act of negligence, an ownership right over a specific item).
• Identification: The Soshōbutsu is identified by analyzing the plaintiff's requested relief as stated in the "Gist of Claim" (Seikyū no shushi 請求の趣旨) and the factual allegations in the "Cause of Action" (Seikyū no gen'in 請求の原因) sections of the complaint, and then pinpointing the single, corresponding substantive legal right that these elements point to.
• Implication: Each distinct substantive right gives rise to a separate Soshōbutsu. For example, under this theory, a claim for payment of the principal of a loan and a claim for accrued interest on the same loan might be considered two separate Soshōbutsu because they are based on distinct (though related) substantive rights. Similarly, different legal grounds for claiming the same relief (e.g., seeking return of property based on ownership versus based on a lease agreement) would constitute different Soshōbutsu.

B. The "New" Subject Matter Theory (Procedural Law Theory / Two-Limbed Theory / Disputed Facts Theory - 新訴訟物理論・訴訟法説・二分肢説・紛争事実説 Shin soshōbutsu riron / Soshō-hō setsu / Nibunshi-setsu / Funsō jijitsu setsu)

• Core Idea: This more modern and now prevailing set of theories views the Soshōbutsu not just as the abstract substantive right, but more as the plaintiff's concrete demand for a specific judicial pronouncement (relief) based on a particular factual grievance or dispute unit presented to the court.
• Identification: The Soshōbutsu is typically identified by the combination of:
  1. The specific type and content of the relief sought by the plaintiff (e.g., payment of a sum, delivery of an item, declaration of a status, formation of a legal relationship).
  2. The essential factual allegations underpinning that request for relief, often viewed as a single "dispute unit" or "social grievance."
• Implication (under a common formulation of the new theory, often called the "two-limbed theory" - nibunshi-setsu): A single set of core underlying social facts or a single transactional event should generally give rise to only one Soshōbutsu, even if substantive law might offer multiple legal characterizations or remedies based on those facts. For instance, if a single act of non-performance under a contract causes various types of damages, the claim for damages arising from that single breach might be considered one Soshōbutsu, regardless of how the damages are itemized or legally categorized. The focus is more on the "claim for relief" as a whole unit presented for judicial resolution.

C. Prevailing View in Japan

The new subject matter theory, in its various formulations (particularly the two-limbed theory or approaches focusing on the concrete demand for judgment), is now the dominant view among Japanese legal scholars and is largely reflected in the practice of the courts, including the Supreme Court. This approach is generally seen as better serving the functions of Soshōbutsu, especially in defining the scope of res judicata more broadly to prevent piecemeal litigation of what is essentially a single underlying dispute.
However, the influence of the old theory is not entirely absent, and the application can be quite nuanced and flexible depending on the specific context of the case and the type of claim involved. The courts often strive for a practical identification that aligns with the purpose of resolving the actual dispute comprehensively.

III. How Soshōbutsu is Identified and Specified in Practice

Regardless of the theoretical nuances, the Soshōbutsu is practically identified and delineated by the plaintiff through their initial pleading:

• The Complaint (Sojō 訴状):
  • "Gist of Claim" (Seikyū no shushi 請求の趣旨): This section precisely states the judgment sought from the court (e.g., "The defendant shall pay the plaintiff JPY X."). It frames the ultimate relief.
  • "Cause of Action" (Seikyū no gen'in 請求の原因): This section sets out the concrete factual allegations that the plaintiff claims entitle them to the relief specified in the Seikyū no shushi. These facts must be sufficient to identify the claim and distinguish it from others.

The court and the defendant understand the Soshōbutsu based on these two components of the complaint. The plaintiff must plead with sufficient clarity for the Soshōbutsu to be identifiable.

IV. The Number of Soshōbutsu (Plurality of Claims - 訴訟物の個数 Soshōbutsu no kosū)

Determining whether a lawsuit involves one or multiple Soshōbutsu is crucial.

• If a plaintiff has several distinct claims against the same defendant, these may constitute multiple Soshōbutsu which can potentially be joined in a single lawsuit (objective joinder of claims).
• Example 1 (Loan): If a plaintiff claims repayment of loan principal and, separately, accrued interest, under the old theory, these might be two Soshōbutsu. Under the new theory, if both arise from the same loan agreement and the same factual context of non-payment, they might be seen as components of a single, broader claim for monies due under that loan, or at least very closely related claims stemming from one dispute unit.
• Example 2 (Contract Termination vs. Damages): A claim seeking termination of a contract and a separate claim seeking damages for past breaches of that same contract are generally treated as two distinct Soshōbutsu because they seek different types of relief based on different (though related) legal evaluations of the facts.
• Example 3 (Property): A claim for the return of property based on ownership right (shoyūken ni motozuku henkan seikyū 所有権に基づく返還請求) is a different Soshōbutsu from a claim for the return of the same property based on a possessory right under a lease (chinshakuken ni motozuku henkan seikyū 賃借権に基づく返還請求).

The identification of the number of Soshōbutsu has direct implications for the application of rules on joinder of claims, the possibility of rendering partial judgments, the scope of amendments, and, critically, the extent of res judicata.

V. Impact of Soshōbutsu on Key Procedural Aspects

1. Res Judicata (Objective Scope):
   As stated, the preclusive effect of a final judgment is defined by the Soshōbutsu. The new theory, by potentially defining the Soshōbutsu more broadly around a "dispute unit," can lead to a wider preclusive effect. This means that if a plaintiff sued based on a certain set of facts but failed to claim all available remedies related to that core factual grievance, they might be barred by res judicata from bringing a subsequent suit for those other remedies if they are deemed part of the same Soshōbutsu that was (or should have been) resolved in the first action. This promotes comprehensive dispute resolution.
2. Amendment of Claims (Uttae no henkō 訴えの変更) (Art. 143 CCP):
   A plaintiff may amend their claim (which can involve changing the Soshōbutsu) provided that the "basis of the claim" (seikyū no kiso 請求の基礎) remains the same. The Soshōbutsu theory influences how courts assess whether the underlying factual foundation is sufficiently common to permit an amendment. A broader conception of the factual dispute unit under the new theory might allow for more flexibility in amendments.
3. Prohibition of Double Litigation (Nijū kiso no kinshi 二重起訴の禁止) (Art. 142 CCP):
   This rule prohibits filing an action when an identical action (same parties, same Soshōbutsu) is already pending in another court. The definition of Soshōbutsu is therefore critical for determining if an action is "identical."

VI. Strategic Importance for Businesses

Understanding the concept of Soshōbutsu is not merely academic; it has direct strategic importance for businesses involved in Japanese litigation:

• Framing the Initial Claim: How a business, as a plaintiff, defines its claim in the complaint (the Seikyū no shushi and Seikyū no gen'in) will determine the Soshōbutsu. This initial framing can have long-lasting consequences for what is ultimately adjudicated and what might be precluded by res judicata in the future.
• Scope of Dispute Resolution: A clear understanding of Soshōbutsu helps in deciding whether to address all related grievances stemming from a transaction in a single lawsuit or whether certain aspects might constitute separate Soshōbutsu that could be litigated independently (if permissible and strategically sound).
• Assessing Res Judicata Effects: When faced with a prior judgment, or when considering future litigation after a judgment, analyzing the Soshōbutsu of the earlier case is essential to determine what claims are now barred.
• Defensive Strategy: As a defendant, understanding the plaintiff's asserted Soshōbutsu is key to formulating an effective defense and to assessing the potential scope of the judgment's preclusive effects.

Conclusion

The "Subject Matter of Litigation," or Soshōbutsu, is a highly theoretical yet profoundly practical concept that lies at the very heart of Japanese civil procedure. It is the central organizing principle that defines the scope of judicial inquiry, dictates the reach of a final judgment's preclusive power (res judicata), and influences crucial procedural decisions regarding amendments, joinder, and the prohibition of duplicative lawsuits. While the nuances of the "old" versus "new" theories continue to be debated by scholars, the prevailing judicial practice leans towards a more encompassing definition centered on the plaintiff's specific demand for relief based on an underlying factual grievance. For businesses, a strategic appreciation of how their claims will be identified and treated as Soshōbutsu by Japanese courts is indispensable for effective litigation planning, risk management, and achieving conclusive resolution of their disputes.