Who Bears the Burden of Proof in a Japanese Civil Lawsuit, and Are There Ways to Alleviate It?

Japanese Attorney at Law - Bengoshi L.L.

• 10 min read

In any legal contest, the question of who needs to prove what is fundamental. The "burden of proof" (shōmei sekinin – 証明責任) is a critical concept in Japanese civil litigation, as it determines which party bears the risk of not persuading the court on a particular factual issue. If a key fact remains unproven or in a state of ambiguity after all evidence has been presented, the party saddled with the burden of proving that fact will typically lose on that issue, and potentially the case.

This article explores how the burden of proof is allocated in Japanese civil lawsuits, the distinction between its objective and subjective aspects, and, importantly, the various legal mechanisms and judicial approaches that can serve to alleviate this burden for litigants.

Understanding the Burden of Proof in Japan

The concept of burden of proof in Japanese civil procedure has two main facets:

A. Objective Burden of Proof (Kyakkanteki Shōmei Sekinin) – The Risk of Non-Persuasion

This refers to the ultimate risk a party bears if a fact essential to their case remains in a state of non liquet (J.: shin'i fumei – 真偽不明), meaning its truth or falsity cannot be definitively determined by the court even after considering all the evidence presented.

  • No Refusal to Judge: A Japanese court cannot refuse to render a judgment simply because a crucial fact is shrouded in uncertainty. It must decide the case one way or the other.
  • Consequence of Non Liquet: When a fact remains in non liquet, the law effectively treats that fact as not existing for the purpose of the judgment. The party who would benefit from the legal effect that arises if that fact were true is the one who suffers the disadvantage of that legal effect not materializing. This ultimate risk of non-persuasion regarding a material fact is the essence of the objective burden of proof.

B. Subjective Burden of Proof (Burden of Production – Shukanteki Shōmei Sekinin / Shōko Teishutsu Sekinin)

Also known as the "burden of producing evidence" (shōko teishutsu sekinin – 証拠提出責任), this refers to the practical obligation on a party during the course of the litigation to come forward with evidence to support its factual allegations.

  • Dynamic Nature: While the objective burden of proof for a particular ultimate fact is fixed, the subjective burden of production can shift back and forth between the parties during the trial as evidence is introduced. Once a party produces sufficient evidence to make a prima facie case for a fact, the practical burden may shift to the opposing party to produce counter-evidence.
  • Relationship: Generally, the party who bears the objective burden of proof for a fact also carries the initial subjective burden of producing evidence related to that fact. However, as discussed later, considerations of fairness, good faith, or significant imbalances in access to evidence can sometimes influence the practical allocation of the burden of production.

The predominant principle guiding the allocation of the objective burden of proof in Japan is the "Legal Requirements Classification Theory" (hōritsu yōken bunrui setsu – 法律要件分類説). This theory, widely accepted in both case law and academic doctrine, dictates that each party bears the burden of proving the existence of facts that constitute the legal requirements favorable to their own position under the applicable substantive law (e.g., the Civil Code, Commercial Code, etc.).

In practice, this generally means:

  • The Plaintiff's Burden: The plaintiff typically bears the burden of proving all the facts necessary to establish their asserted right or claim (kenri konkyo jijitsu – 権利根拠事実). For example, in a breach of contract claim, the plaintiff must prove the existence of a valid contract, their own performance (if it's a condition for the defendant's duty), the defendant's breach, and the resulting damages.
  • The Defendant's Burden: The defendant, conversely, bears the burden of proving facts that would defeat the plaintiff's otherwise valid claim. These can be categorized as:
    • Facts extinguishing the right (kenri shōmetsu jijitsu – 権利消滅事実): E.g., payment of a debt, waiver of a right, rescission or cancellation of a contract, expiration of the statute of limitations (prescription).
    • Facts preventing the right from arising (kenri shōgai jijitsu – 権利障害事実): E.g., lack of legal capacity to contract, duress or mistake rendering a contract void or voidable, a fictitious declaration of intent (sham transaction).
    • Facts establishing an affirmative defense right (kenri soshi jijitsu – 権利阻止事実): E.g., the right to demand simultaneous performance in a bilateral contract.

While this classification theory is the general guide, some statutes explicitly allocate the burden of proof for specific issues, overriding the general principle. For example, the Act on Securing Compensation for Automobile Accidents (often called the Jibai Hō – 自賠法) in its Article 3 proviso effectively places the burden on the vehicle operator/owner to prove their absence of fault to escape liability in many personal injury cases. Similarly, the 2017 amendments to the Civil Code clarified that in a breach of contract claim under Article 415, the debtor (defendant) bears the burden of proving that the breach was not attributable to their fault (proviso to Art. 415).

In situations where the classification of a particular legal requirement is not straightforward, courts may also consider underlying principles of fairness, policy objectives, and which party typically has better access to evidence concerning that fact. Examples from case law show this nuanced application, such as the Supreme Court judgment of February 2, 1960, which placed the burden of proving the good faith of a third party (in a dispute over a fictitious declaration) on the party alleging the transaction was null and void against that third party.

Mechanisms for Alleviating the Burden of Proof

Recognizing that a rigid application of the burden of proof can sometimes lead to inequitable outcomes, especially in situations where there is a significant imbalance in information or resources between parties, Japanese law and judicial practice incorporate several mechanisms to alleviate this burden:

A. Shifting the Burden of Proof (Shōmei Sekinin no Tenkan – 証明責任の転換)

This involves a formal reallocation of the objective burden of proof from the party who would normally bear it to the opposing party.

  • Legislative Shifts: As mentioned, specific statutes can explicitly shift the burden of proof for certain claims or defenses. The Automobile Accidents Compensation Act is a prime example of such a policy-driven shift to protect victims.
  • Judicial Shifts (Interpretive): In certain types of "modern lawsuits" such as medical malpractice, environmental pollution, or complex product liability cases, plaintiffs often face severe difficulties in accessing information necessary to prove negligence or causation, as much of this information is held by the defendant (e.g., hospitals, manufacturers). While there is no general doctrine allowing courts to freely shift the burden of proof by interpretation in all such cases, there is ongoing academic discussion and some judicial inclination, in very specific circumstances and often through the use of presumptions (discussed below), to effectively place a higher burden of explanation or rebuttal on the defendant who possesses superior knowledge or control over the evidence.

Substantive law itself often establishes legal presumptions that can significantly aid a party in meeting their burden of proof.

  • Definition: A legal presumption dictates that if a party proves certain basic, prerequisite facts (Fact A and Fact B), then another fact (Fact C, often the ultimate fact in issue or a legal right) is deemed to be true, unless and until the opposing party adduces sufficient evidence to prove the contrary (i.e., the non-existence of Fact C).
  • Effect: The party benefiting from the presumption is relieved of the burden of directly proving the presumed fact; they only need to prove the foundational facts. The burden of disproving the presumed fact then effectively shifts to the opponent.
  • Examples from the Civil Code:
    • Presumption of continuation of possession between two points in time if possession at both points is proven (Art. 186(2)).
    • Presumption that a possessor of a thing possesses it with the intent to own, peacefully, openly, and in good faith (Art. 186(1)).
    • Presumption that a child conceived by a wife during marriage is the child of her husband (Art. 772).
    • Presumption that a possessor exercises the right they possess lawfully (Art. 188).

C. Factual Presumptions / Prima Facie Evidence (Ichidan no Suitei – 一応の推定 or Jijitsujō no Suitei – 事実上の推定)

Even in the absence of a specific statutory presumption, courts can, and often do, draw strong inferences of fact based on common experience and logical reasoning. This is often referred to as ichidan no suitei (literally, "presumption for the time being" or prima facie evidence) or factual presumption.

  • Mechanism: If a party establishes a set of foundational facts which, according to ordinary human experience, strongly suggest the existence of the ultimate fact they need to prove, the court may infer that ultimate fact to be true, unless the opposing party comes forward with a credible explanation or evidence that rebuts this inference.
  • Effect: While this does not formally shift the objective burden of proof, it practically shifts the subjective burden of production (or burden of going forward with evidence) to the opponent. The opponent must then offer evidence to negate the inference or provide a plausible alternative explanation for the foundational facts. This process of rebuttal is sometimes referred to as offering "indirect rebuttal evidence" (kansetsu hanshō – 間接反証).
  • Case Law Examples:
    • If someone is found to have felled trees on another person's land, it might be presumed, prima facie, that this act was done either intentionally or negligently (Great Court of Cassation judgment, February 25, 1918).
    • In a medical context, if a patient develops an abscess at an injection site shortly after receiving an injection, and there is no other obvious cause, a court might infer some fault in the sterilization procedures, even if the precise point of failure (e.g., needle, skin, medication) cannot be pinpointed by the plaintiff (Supreme Court judgment, July 28, 1964). This is akin to res ipsa loquitur reasoning in common law.

D. Adverse Inferences from Spoliation or Non-Production of Evidence (Shōmei Bōgai – 証明妨害)

When a party improperly hinders the other party's access to proof, Japanese law provides for potential adverse consequences.

  • Failure to Comply with Document Production Order (CCP Art. 224): If a party fails to comply with a court order to produce a document, the court may, in its discretion, deem the opposing party's assertions about the contents of that document to be true. If the non-production was intended to obstruct the opponent's use of the document, and proving the fact in question by other means is extremely difficult for the opponent, the court can even deem the fact to be proven by that document as true (CCP Art. 224(3)).
  • Refusal by a Party to Testify (CCP Art. 208): If a party, when ordered to be examined as a witness (party-witness), refuses to appear, take an oath, or testify without justifiable reason, the court may deem the opposing party's assertions concerning the matters about which the party was to be examined to be true.
  • General Principle: Beyond these specific statutory provisions, a more general principle against "obstruction of proof" or spoliation is recognized. If a party is found to have intentionally destroyed or concealed relevant evidence, courts may draw adverse inferences against them, effectively easing the evidentiary burden on the other side. A Tokyo High Court judgment on January 30, 1991, hinted at broader potential consequences like shifting the burden of proof or lowering the standard of proof.

E. Theory of an Obligation to Cooperate in Clarifying Facts (Jian Kaimei Gimu Riron – 事案解明義務の理論)

In complex litigation scenarios characterized by significant informational asymmetry—where one party (often the defendant, such as a hospital in a medical malpractice suit or a factory in an environmental pollution case) possesses vastly more information and technical knowledge about the disputed events than the other—a legal theory known as the "obligation to clarify facts" (jian kaimei gimu riron – 事案解明義務の理論) has gained traction in academic discourse.

  • Core Idea: This theory posits that the party with overwhelmingly superior access to relevant information has a procedural duty, stemming from the overarching principle of good faith and fairness in litigation, to actively cooperate in clarifying the facts, even if they do not formally bear the burden of proof for those facts.
  • Potential Consequences of Breach: Failure to fulfill this duty of cooperation could lead to the court drawing adverse inferences, effectively easing the proving party's burden, or even, in some views, leading to a practical shift in the burden of production.
  • Judicial Recognition: While not a fully established doctrine with clearly defined parameters and automatic sanctions in general civil cases, the underlying sentiment has found some resonance. A notable Supreme Court judgment in an administrative law context (concerning the safety of a nuclear reactor, judgment of October 29, 1992) required the defendant government agency, which held all the relevant safety data, to adequately substantiate its safety determinations. The Court indicated that a failure to do so could lead to an inference that its safety judgment was unreasonable. This approach, while in an administrative case, reflects a judicial willingness to place a heavier explanatory burden on the party controlling information.

F. Court Determination of Damages When Precise Proof is Difficult (CCP Art. 248)

A specific statutory provision that alleviates the burden of proof concerns the quantification of damages. Article 248 of the CCP provides that if it is established that some damage has occurred, but it is extremely difficult, due to the nature of the damage, to prove its precise monetary amount, the court may determine a reasonable amount of damages based on the entirety of the oral arguments and the results of the evidence examination. This allows courts to award damages in situations where strict proof of quantum is impractical, such as for certain types of non-pecuniary losses or complex future damages. The Supreme Court (judgment of June 10, 2008) has affirmed that applying this provision where its conditions are met can be a duty of the court, not just a matter of discretion.

Standard of Proof (Shōmei-do – 証明度)

For a fact to be considered "proven" in a Japanese civil trial, the court must achieve a certain level of conviction. Japanese case law often describes this standard as requiring a "high degree of probability" – a level of certainty where an ordinary person, after considering all the evidence and in light of common experience, would harbor no reasonable doubt about the truthfulness of the fact (e.g., Supreme Court judgment, October 24, 1975). This standard is generally considered to be higher than the "preponderance of the evidence" standard typically used in U.S. civil cases, though precise comparisons between verbal formulations of proof standards across different legal cultures can be challenging.

Conclusion

The allocation of the burden of proof is a critical determinant of outcomes in Japanese civil litigation. While the Legal Requirements Classification Theory provides the foundational framework, Japanese law and judicial practice have evolved several important mechanisms—ranging from explicit statutory burden-shifting and legal presumptions to more flexible factual presumptions, adverse inferences for evidentiary misconduct, and an emerging emphasis on duties of factual clarification in cases of informational imbalance. These tools aim to ensure that the burden of proof, while a necessary component of the adversarial process, does not lead to substantively unjust results, particularly where one party faces inherent disadvantages in accessing or proving crucial facts.

For businesses, including U.S. companies, litigating in Japan, a sophisticated understanding of not only who formally bears the burden for each element of a claim or defense but also how these various burden-alleviating principles and presumptions might come into play is essential for accurately assessing litigation risks and formulating effective trial strategies.