Third-Party Intervention in Japanese Lawsuits: What are the Court Fee Consequences for Independent Party Intervention?

In the course of litigation between two parties—a plaintiff and a defendant—it sometimes becomes apparent that a third party has a direct and substantial interest in the subject matter of the dispute or the outcome of the lawsuit. Japanese civil procedure, under Article 47 of the Code of Civil Procedure (CCP), provides a mechanism for such a third party to enter the ongoing lawsuit not merely as an observer or assistant, but as a full, independent party asserting their own rights. This is known as "independent party intervention" (独立当事者参加 - dokuritsu tōjisha sanka). While this procedure promotes comprehensive dispute resolution, it raises important questions regarding court fees, specifically, what financial obligations the intervening third party incurs.

Understanding Independent Party Intervention (CCP Article 47)

Independent party intervention allows a third party to join an existing lawsuit by filing their own claims against one or both of the original litigating parties. The primary purpose of this procedural device is to facilitate the resolution of multi-polar disputes—where three or more distinct interests are in conflict over the same subject matter—within a single, consolidated proceeding, thereby ensuring consistent judgments and avoiding duplicative litigation.

To achieve this consistency, Article 47(4) of the CCP mandates that the procedural rules applicable to "necessarily joined parties" (those for whom a single, unified judgment is required, as per CCP Article 40(1)-(3)) are applied by analogy to all parties involved after an independent intervention. This means, for example, that actions taken by one party might affect others, and the judgment must be consistent across all claims.

There are two main types of independent party intervention recognized under CCP Article 47(1):

1. Intervention to Prevent Fraudulent or Prejudicial Litigation (詐害防止参加 - sagai bōshi sanka):
   This occurs when the third party alleges that the ongoing lawsuit between the original plaintiff and defendant is collusive, fraudulent, or will otherwise unjustly prejudice the third party's rights. For instance, a creditor might intervene if they suspect a lawsuit involving their debtor is designed to wrongfully divest the debtor of assets that could satisfy the creditor's claim. The intervener's primary goal here is to protect their existing rights from being undermined by the outcome of the original suit.
2. Intervention to Assert One's Own Right (権利主張参加 - kenri shuchō sanka):
   This type of intervention happens when the third party claims that the legal right, or a part of it, being disputed between the original plaintiff and defendant actually belongs to the intervener. Alternatively, the intervener might assert that they possess a superior or incompatible right concerning the subject matter of the original lawsuit. A common example cited in the source text is where Plaintiff X sues Defendant Y for a debt (e.g., a sales price of ¥2 million), and a third party, Z, intervenes claiming that X had assigned this very receivable to Z prior to the lawsuit. In this scenario, Z would typically sue X for a declaration that the receivable now belongs to Z, and sue Y for the payment of the ¥2 million.

While traditionally envisioned for three-sided disputes, Japanese law now explicitly allows for "one-sided intervention" (片面的参加 - henmen-teki sanka), where the intervener directs their claims against only one of the original litigating parties.

The author of the source text notes an interesting point regarding the scope of the intervener's claims: historically, mainstream views did not necessarily require an intervener to formally demand the dismissal of the original plaintiff's claim against the original defendant. However, the author argues that allowing the intervener to make such demands concerning the original claim (e.g., that X's claim against Y in the example above be dismissed because the right belongs to Z) is logical and aligns with the intervention's purpose, especially in cases of intervention to prevent prejudicial litigation.

Court Fee Calculations for the Independent Party Intervener

The act of intervening as an independent party carries court fee implications for the intervener.

Jurisdictional "Value of Suit" (So'gaku)

The question of jurisdictional so'gaku is not a primary concern for the act of intervention itself. This is because the intervention occurs within a lawsuit that is already pending before a court that has jurisdiction over the original dispute.

Court Fee "So'gaku" (手数料訴額 - Tesūryō So'gaku) – The General Rule

Despite the intervention taking place within an existing procedural framework, the Civil Procedure Costs Act (民事訴訟費用等に関する法律 - Minso Hiyōhō), in its Appended Table 1, Item 7, generally treats the independent party intervener's application as the initiation of their own, new claims. Consequently, the intervener is typically required to pay court fees based on the "value of suit" (so'gaku) of the specific claims they are asserting through their intervention, calculated as if they were filing a separate, new lawsuit.

• Calculating the Intervener's So'gaku: The so'gaku is determined by the value of the claims the intervener lodges against the original plaintiff and/or defendant. If the intervener brings multiple claims, the standard rules for so'gaku calculation for joined claims apply to their set of claims. This means that if the intervener's multiple claims are economically unitary, their values are not aggregated; rather, the highest value among those unitary claims determines the intervener's so'gaku for fee purposes.
  • Revisiting the example from the source text: "X sues Y for a ¥2 million sales price. Z intervenes, claiming X assigned this ¥2 million receivable to Z. Z might sue X for a declaration that the receivable belongs to Z (valued, for instance, at ¥2 million) and sue Y for payment of the ¥2 million (also valued at ¥2 million). Since both of Z's claims concern the same underlying ¥2 million economic interest (the receivable), these claims by Z are considered economically unitary. Thus, Z's so'gaku for calculating their intervention fee would be ¥2 million (representing the core economic interest), not an aggregated ¥4 million."
• Intervention at the Appeal Stage: If an independent party intervention occurs for the first time at the appeal stage, the court fee payable by the intervener for their claims is typically 1.5 times the fee that would have been due had those same claims been filed in the first instance.

Critique of the Current Fee Rule for Interveners (Author's Perspective from the Source Text)

The author of the source text raises a significant theoretical and practical critique of the rule requiring independent interveners to pay full separate court fees as if initiating a new action.

• The core issue identified is that this rule seems to overlook the principle of economic unity when the intervener's claim is substantially identical to, or directly competes for, the same economic interest already being litigated by the original plaintiff. For instance, if both the original plaintiff and the intervening party are claiming the same debt from the defendant, the current system could result in the court system being compensated twice for adjudicating what is, in economic substance, a single disputed sum.
• The Civil Procedure Costs Act's rationale appears to emphasize the independent litigant status of the intervener, who can pursue their claims without being bound by the litigation conduct or admissions of the original parties. While this independent status is undeniable, the author argues that it is a separate matter from the principle of not double-counting the economic "object" (対象 - taishō) of the dispute for so'gaku purposes when there is clear economic overlap.
• The author suggests that this rule, as stipulated in Appended Table 1, Item 7 of the Civil Procedure Costs Act, warrants reconsideration from both legislative and interpretive perspectives to better align with the underlying principles of fairness in court fee assessment and the economic realities of multi-polar disputes resolved through intervention.

Conclusion

Independent party intervention under Article 47 of the CCP is a vital procedural mechanism in Japan that allows third parties with direct legal interests to become active participants in ongoing lawsuits, ensuring that all related claims are resolved comprehensively and consistently. However, those considering such intervention must be aware of the court fee implications. Current Japanese law, through the Civil Procedure Costs Act, generally requires independent interveners to pay court fees based on the value of their own asserted claims, as if they were initiating a new lawsuit. While this reflects their status as autonomous litigants, legal commentators have pointed out potential inequities when the intervener's claim is economically coextensive with that of an original party, suggesting that the principles of economic unity, which prevent fee aggregation in other contexts, might ideally be given more consideration here.