Appealing a First Instance Judgment in Japan (Koso Appeal): What are the Possible Outcomes and How Does the "Prohibition of Disadvantageous Change" (Furieki Henkō Kinshi) Work?

Japanese Attorney at Law - Bengoshi L.L.

01 Jun 2025 • 12 min read

The Japanese judicial system provides litigants with avenues to challenge unfavorable judgments rendered by courts of first instance. The primary mechanism for this is the Koso appeal (控訴), a first-level appeal typically lodged from a District Court (地方裁判所 - Chihō Saibansho) or Summary Court (簡易裁判所 - Kan'i Saibansho) judgment to the competent High Court (高等裁判所 - Kōtō Saibansho). Unlike some appellate systems that focus solely on errors of law, a Koso appeal in Japan involves a comprehensive re-examination of the case, including factual matters. Understanding the potential outcomes of a Koso appeal and the crucial "Principle of Prohibition of Disadvantageous Change" (Furieki Henkō Kinshi no Gensoku - 不利益変更禁止の原則) is essential for any party contemplating or involved in appellate proceedings.

(It's worth noting that Japan also has a second level of appeal, the Jokoku appeal (上告), typically to the Supreme Court, which is primarily concerned with errors in constitutional interpretation or significant legal errors. Additionally, a "leapfrog appeal" (飛越上告 - hiyaku jōkoku) allows parties, by agreement and under specific conditions, to appeal directly from a first instance judgment to the final appellate court, bypassing the Koso stage, primarily for questions of law.)

The Nature and Purpose of a Koso Appeal

A Koso appeal is not merely a review of the first instance court's decision for errors. The Japanese system for Koso appeals operates under a "continuous trial system" (zokushinsei - 続審制). This means the High Court, acting as the Koso appellate court, functions as a second fact-finding instance. It is not bound by the factual findings of the first instance court and can:

Re-examine all evidence presented at the first instance.
Allow the introduction of new evidence by the parties, subject to certain restrictions (e.g., evidence that could have been presented earlier without good reason might be excluded if it would cause undue delay).
Conduct its own examination of witnesses and other evidence.

The fundamental objective of the Koso appeal is to provide an opportunity to correct any errors—whether of fact, law, or procedure—made by the first instance court, and ultimately to ensure that a just and proper judgment is rendered based on a thorough examination of the case.

Possible Judgments of the Koso Appellate Court

When a High Court adjudicates a Koso appeal, its final decision (excluding ancillary orders like those concerning provisional execution, litigation costs, or minor corrections to the judgment text) can take several forms, impacting the appeal itself and the original first instance judgment:

A. Dismissal of the Koso Appeal as Inadmissible (Kōso Kyakka - 控訴却下)

This type of judgment does not address the merits of the first instance decision or the grounds of appeal. Instead, it concludes that the Koso appeal itself is procedurally flawed and inadmissible, and that this defect cannot be rectified (Article 290 of the Code of Civil Procedure - CCP).

Common reasons for a kōso kyakka include:

The appeal being filed after the statutory two-week appeal period has expired.
The appellant lacking a legally recognized "interest to appeal" (jōso no rieki - 上訴の利益 or fufuku no rieki - 不服の利益). This can happen, for example, if the appellant was entirely successful in the first instance judgment (i.e., their claim was fully granted, or the claim against them was fully dismissed) and they are attempting to appeal a point made in the reasoning of the judgment that does not, by itself, grant them a right to appeal because it has no res judicata effect and causes them no current legal disadvantage.
Other significant procedural defects in the filing or prosecution of the appeal that are deemed incurable.

If the defect is clear and cannot be corrected, the appellate court may issue this dismissal by way of a judgment without holding oral arguments.

B. Rejection of the Koso Appeal on the Merits (Kōso Kikyaku - 控訴棄却)

This judgment is rendered when the appellate court, after reviewing the case on its merits (including any new evidence or arguments presented at the appellate stage), concludes that the first instance judgment was ultimately correct in its outcome (Article 302 CCP).

This applies if the appellate court finds that "the judgment of the first instance court is justifiable" (Art. 302(1) CCP).
It also applies "even where the judgment of the first instance court is not justifiable for its reasons, if it is justifiable for other reasons" (Art. 302(2) CCP). This means if the first instance court reached the right result but for the wrong reasons, and the appellate court finds valid alternative grounds to support that same result, it will still reject the appeal and uphold the outcome.

A kōso kikyaku requires the appellate court to have held oral arguments and considered the substance of the appeal. It's important to distinguish this from a kōso kyakka: if, for example, the first instance judgment was a procedural dismissal of the action (uttae kyakka - 訴え却下), and the appellate court agrees with this procedural outcome, the correct judgment on appeal is a rejection of the Koso appeal (kōso kikyaku), not a dismissal of the Koso appeal itself.

However, there are two key exceptions where the appellate court will not simply issue a kōso kikyaku even if it agrees with the ultimate outcome of the first instance judgment. These occur when the res judicata effect of the appellate judgment would differ significantly from that of the first instance judgment, even if the "bottom line" (e.g., claim dismissed) is the same:

If the first instance court dismissed the action on procedural ground A (uttae kyakka), but the appellate court finds that the dismissal was correct but should have been based on a different procedural ground B. Since the res judicata of a procedural judgment often attaches to the specific ground for dismissal, the appellate court should reverse the first instance judgment and issue its own procedural dismissal detailing ground B.
If the first instance court dismissed the plaintiff's claim based on the defendant's successful defense of set-off (sōsai no kōben - 相殺の抗弁), but the appellate court concludes that the claim should have been dismissed because it was non-existent from the outset (for reasons independent of the set-off). The res judicata effects are different: a dismissal based on set-off creates res judicata on both the plaintiff's primary claim (extinguished) and the defendant's counter-claim used for set-off (also extinguished up to the amount offset – Article 114(2) CCP). A dismissal based on the primary claim's initial non-existence only creates res judicata regarding that primary claim. To ensure the correct res judicata scope, the appellate court should reverse the first instance judgment and issue its own substantive dismissal based on the non-existence of the primary claim, thereby avoiding the Article 114(2) res judicata on the set-off claim.

C. Reversal (Torikeshi - 取消し) or Modification (Henkō - 変更) of the First Instance Judgment

This is the outcome when the appellate court finds the first instance judgment to be incorrect in its result—due to errors of fact, misapplication of law, or significant procedural errors that affected the outcome—and therefore upholds the appeal (at least in part). The main text of the appellate judgment will typically state that the first instance judgment is "reversed" (全部取消し - zenbu torikeshi, full reversal; 一部取消し - ichibu torikeshi, partial reversal) or "modified."

When a first instance judgment is reversed or modified, the appellate court, in its capacity as a fact-finding court under the zokushinsei system, must then take further dispositive action. This generally takes one of three forms:

Rendering Its Own Judgment (Jihan - 自判): This is the primary and most common course of action following a reversal. The High Court, having re-examined the facts and law (including any new evidence and arguments from the Koso stage), will render its own comprehensive judgment on the merits of the case. A judgment that "modifies" the first instance decision is, in substance, a partial reversal followed by the appellate court's own new judgment for the modified parts.
Remand to the First Instance Court (Sashimodoshi - 差戻し): In certain situations, instead of deciding the case itself, the appellate court will reverse the first instance judgment and send the case back to the first instance court for further proceedings.
- Mandatory Remand (Article 307 CCP): If the first instance judgment had improperly dismissed the action itself on procedural grounds (uttae kyakka), and the appellate court finds this dismissal to be erroneous (i.e., the action was, in fact, procedurally admissible), it must reverse the dismissal and remand the case to the first instance court. This is to protect the parties' "benefit of instances" (shinkyū no rieki - 審級の利益), ensuring they have the opportunity for two full levels of factual adjudication on the merits.
  - Exceptions to Mandatory Remand: Remand is not required under Article 307 if the appellate court, despite finding the procedural dismissal erroneous, also determines that the plaintiff's claim is clearly without any merit on its face, or if the first instance court, despite its procedural dismissal, had already substantially examined the merits of the case such that a remand would not offer any additional benefit of instances. Furthermore, if the appellate court finds a different procedural defect that still warrants dismissal of the action, it can issue its own procedural dismissal (jihan) rather than remanding.
- Discretionary Remand (Article 308, Paragraph 1 CCP): If the appellate court reverses a first instance judgment that did decide on the merits, but finds that substantial further oral argument or fact-finding is necessary and is best conducted at the first instance level, it may (at its discretion) remand the case. This might occur, for example, if a deemed admission at the first instance is overturned on appeal, requiring extensive new evidence and examination on that now-disputed point, or if the first instance completely failed to address a critical issue.
Transfer to a Competent Court (Isō - 移送) (Article 309 CCP): If the first instance judgment is reversed specifically because the first instance court lacked exclusive jurisdiction over the case, the appellate court must transfer the case by judgment to the first instance court that does possess proper (exclusive) jurisdiction. A transfer is to a different first instance court, not a remand to the same (but non-competent) court.

A Cornerstone of Appellate Practice: The Prohibition of Disadvantageous Change (Furieki Henkō Kinshi no Gensoku)

A fundamental principle governing Koso appeals in Japan is the "Prohibition of Disadvantageous Change" (Furieki Henkō Kinshi no Gensoku - 不利益変更禁止の原則). This principle is primarily rooted in Article 304 CCP, which states, "An appeal may not be made with regard to any part of a judgment of prior instance against which the appellant has no ground for complaint."

The Principle Explained: In essence, an appellant (the party who filed the Koso appeal) cannot be put in a worse legal position as a result of their own appeal than they were under the original first instance judgment.

Condition: This protection is sacrosanct unless the appellee (the other party, who did not initiate the Koso appeal) also challenges the first instance judgment by filing their own timely Koso appeal or, more commonly, by filing a cross-appeal (futai kōso - 附帯控訴) under Article 293 CCP after the appellant has filed their appeal. A cross-appeal by the appellee can seek modifications unfavorable to the original appellant, thereby expanding the scope of the appellate court's review.
Limitation on Appellate Court's Power: The appellate court's authority to review and alter the first instance judgment is generally confined to the scope of the grievance(s) actually raised by the appealing party (or parties, if both sides appeal or cross-appeal). It cannot, on its own initiative, worsen the appellant's position beyond what they suffered in the first instance judgment if the appellee has not sought such a change.
Corresponding "Prohibition of Advantageous Change": Conversely, a party who did not appeal or cross-appeal cannot typically receive a more favorable outcome from the appellate court than they received at first instance, even if the appellate court believes they were entitled to more. This is an application of the Principle of Disposition (当事者主義 - tōjisha shugi / 処分権主義 - shobunken shugi, under Article 246 CCP) at the appellate level: the court only rules on what is put before it by a party's appeal.
Policy Rationale: This principle encourages parties to exercise their right to appeal by assuring them that, barring action by the other side, their appeal will not result in a net loss compared to the original judgment. It aims to make the appellate process a tool for seeking improvement, not a gamble with the risk of a worse outcome solely due to one's own initiative.

Practical Implications:

Example 1 (Plaintiff Appeals for More, Defendant Pays and Stays Silent): Plaintiff (P) sues Defendant (D) for ¥10 million and the first instance court awards P ¥8 million. P, dissatisfied, files a Koso appeal seeking the remaining ¥2 million. D does not appeal or file a cross-appeal. After the first instance judgment, D pays the ¥8 million awarded. In the Koso appeal, D argues that this payment should be considered. The High Court re-examines the case and concludes that P's original claim was indeed only worth ¥8 million (so the additional ¥2 million P is appealing for is not due), and further notes that D has now paid this ¥8 million.
- Can the High Court modify the judgment to reflect that D now owes ¥0? No. Because only P appealed, the High Court cannot change the first instance award of ¥8 million to P's detriment (i.e., reduce it). P appealed only the ¥2 million they didn't get. The High Court will find that this ¥2 million is not owed and will therefore reject P's Koso appeal (kōso kikyaku). The original ¥8 million judgment effectively stands, even if it has been substantively satisfied post-judgment. For D to get judicial recognition of the payment's effect on the ¥8 million award within that same appellate proceeding, D would have needed to file a cross-appeal.
Example 2 (Alternative Claims and Appeals): P sues D, making a primary claim (e.g., for payment of a ¥10 million sales price) and, in the alternative (preliminarily), a claim for the return of the goods sold if the sales contract is found invalid. The first instance court dismisses P's primary claim but upholds P's preliminary claim for the return of the goods.
- If P alone appeals (challenging the dismissal of the primary sales price claim):
  - If the High Court finds that the primary claim should be upheld (and consequently the preliminary claim for return of goods should be dismissed as its condition – invalidity of contract – is not met), the prevailing view is that the High Court should reverse both parts of the first instance judgment (the dismissal of the primary claim AND the upholding of the preliminary claim). It would then issue its own judgment upholding the primary claim. This is done to avoid the logically inconsistent appearance of P winning both the sales price and the return of the same goods.
  - If the High Court finds that both the primary claim and the preliminary claim should be dismissed: P appealed only the dismissal of the primary claim. P did not appeal the part where they won (the preliminary claim for return of goods). Therefore, under the Prohibition of Disadvantageous Change, the High Court cannot overturn P's victory on the preliminary claim to P's detriment. Since the High Court agrees with the first instance that the primary claim should be dismissed, P's appeal concerning that part is rejected. The net result is that P's entire Koso appeal is rejected, and the first instance judgment (primary claim dismissed, preliminary claim upheld) effectively stands.
- If D alone appeals (challenging the upholding of the preliminary claim for return of goods), and P does not appeal or cross-appeal the dismissal of their primary claim: Suppose the High Court agrees with D that the preliminary claim should have been dismissed, but simultaneously believes that P's primary claim (for the sales price) should have been upheld.
  - According to the prevailing view and Supreme Court precedent (e.g., Supreme Court, March 22, 1983, Hanrei Jihō No. 1074, p. 55), the High Court can only address the part of the judgment D appealed against – i.e., it can reverse the first instance decision on the preliminary claim and dismiss P's claim for return of goods. It cannot, in the absence of an appeal or cross-appeal from P, overturn the first instance dismissal of P's primary claim and rule in P's favor on that point. Doing so would be an advantageous change for the non-appealing P, beyond the scope of D's appeal. P should have filed a cross-appeal if they wanted the dismissal of their primary claim reviewed.

Tension Point: Prohibition of Disadvantageous Change vs. Uniformity of Judgment in Necessary Co-litigation

A significant tension arises when the Prohibition of Disadvantageous Change intersects with the requirement for "Uniformity of Judgment" (gōitsu kakutei - 合一確定) in cases of indispensable necessary co-litigation (where Article 40 CCP applies) or in certain types of independent party intervention (where Article 47, Paragraph 4 CCP also applies Article 40 rules). If achieving a single, consistent judgment for all essential parties necessitates modifying the first instance judgment in a way that affects a non-appealing co-litigant (either to their advantage or disadvantage), which principle prevails?

The Supreme Court has addressed this in key decisions (e.g., Supreme Court, July 20, 1973, Minshu Vol. 27, No. 7, p. 863, concerning independent party intervention; and Supreme Court, March 16, 2010, Minshu Vol. 64, No. 2, p. 498, concerning indispensable co-litigation). The consistent stance is that the requirement for Uniformity of Judgment (gōitsu kakutei) generally takes precedence over a strict application of the Prohibition of (Dis)Advantageous Change with respect to non-appealing co-litigants who are subject to the Article 40 regime.

This means an appellate court can (and often must) modify the first instance judgment concerning a non-appealing indispensable co-litigant if such modification is essential to achieve a legally coherent and uniform outcome for all the indispensable parties involved in that specific relationship. The rationale is that the very nature of such co-litigation demands a single, indivisible judgment, and the procedural rules of appeal must bend to accommodate this overriding substantive and procedural necessity. The scope of the appeal is effectively broadened by the imperative of ensuring a unified adjudication for all parties who must be bound consistently by the outcome.

Conclusion

The Koso appeal provides a crucial opportunity for a comprehensive re-examination of first instance judgments in the Japanese civil justice system. High Courts, acting as a second fact-finding instance, have a range of powers, from dismissing procedurally flawed appeals to fully re-adjudicating cases and issuing their own judgments. Central to navigating this appellate stage is the Prohibition of Disadvantageous Change, a principle that protects appellants from being worsened by their own initiative to appeal, unless the opposing party also seeks changes. However, this principle itself operates within the broader procedural landscape and can be modified by overriding concerns such as the need for uniform judgments in complex multi-party litigation. A thorough understanding of these potential outcomes and guiding principles is indispensable for any party involved in or contemplating a Koso appeal in Japan.