Laying the Foundation: Understanding the Legal Basis for Using Prior Inconsistent Statements in Japanese Trials

I. Introduction: The Evidentiary Tightrope of Prior Statements

In the intricate dance of a Japanese criminal trial, a witness's prior inconsistent statement can be a moment of high drama and critical legal maneuvering. When a witness on the stand tells a story that diverges from an earlier account given to investigators or in other formal settings, it presents a prime opportunity for the opposing counsel to challenge their credibility. However, the use of such statements is not a free-for-all; it is tightly governed by a foundational provision in the Code of Criminal Procedure (CCP)—Article 328—and a set of nuanced procedural rules (Criminal Procedure Rules, or CPR). Understanding this legal framework is essential for any practitioner seeking to effectively use, or defend against the use of, prior inconsistent statements for impeachment in Japan. This article offers a deep dive into these provisions, their legislative intent, key judicial interpretations, and ongoing debates surrounding their practical application.

II. Article 328 CCP: The Gateway to Impeachment with Prior Statements

The cornerstone for admitting prior inconsistent statements for impeachment purposes in Japanese criminal trials is Article 328 of the Code of Criminal Procedure. It reads:

"Even if a document or statement cannot be used as evidence pursuant to the provisions of Articles 321 through 324 [the hearsay rules], it may be used as evidence to challenge the credibility of the testimony of the accused, a witness, or other persons in trial preparation or on a trial date."

This provision is fundamental because it carves out a specific exception to the general prohibition against hearsay evidence, but only for a very particular purpose.

A. Legislative Intent and Core Principle

The inclusion of Article 328 in the post-war Code of Criminal Procedure was a deliberate effort to enhance the tools available for testing the reliability of testimony. Commentators involved in the drafting process, such as Yokoi Daizo (a key figure in formulating the Code), emphasized that this article was designed to make cross-examination more effective. The underlying principle is rooted in common sense and logic: if a person provides conflicting accounts of the same event at different times, their overall reliability on that subject comes into question. The inconsistency itself becomes evidence relevant to assessing the credibility of their current, in-court testimony.

B. Scope of "Challenging Credibility"

Article 328 permits the use of prior statements "to challenge the credibility" (供述の証明力を争うためには, kyōjutsu no shōmeiryoku o arasou tame ni wa) of a witness. This phrase, also found in Criminal Procedure Rule 199-6 which deals with the scope of cross-examination, encompasses several aspects of credibility. Primarily, it relates to potential deficiencies in the witness's:

  • Observation of the events.
  • Memory or recollection of those events.
  • Expression or articulation of their account.

However, it can also extend to challenging credibility based on the witness's potential biases, personal interest in the case's outcome, or any preconceived notions that might color their testimony. The inconsistency in statements can be a symptom of these underlying issues.

C. Key Judicial Clarifications – The Supreme Court Ruling of November 7, 2006

The application of Article 328 has been significantly shaped by judicial interpretation, most notably by a landmark Supreme Court of Japan decision on November 7, 2006 (Keishu Vol. 60, No. 9, p. 561). This ruling brought crucial clarity and, in doing so, revised prior, sometimes more lenient, case law. Key takeaways from this judgment include:

  1. Limitation to Self-Contradictory Statements: The Court affirmed that Article 328 is specifically for impeaching a witness with their own prior statement that contradicts their current testimony. It is not a general license to introduce any contradictory hearsay statement from any source merely because it conflicts with the witness on the stand. The focus is on the witness's own inconsistency.
  2. Formal Requirements for Prior Statements: For a prior statement contained in a document (such as a police statement or deposition) to be admissible for impeachment under this article, it generally must be authenticated as the witness's statement. This typically means the document should bear the witness's signature or personal seal (判子, hanko), evidencing that they acknowledged it as their statement at the time it was made or recorded. Unsigned or unverified notes or summaries may not qualify.

This ruling underscored the need for a reliable link between the prior statement and the witness being impeached.

D. Impeachment vs. Augmentation/Rehabilitation

The predominant interpretation of Article 328, supported by its wording ("to challenge credibility") and influential lower court decisions (e.g., Osaka High Court, October 9, 1990), is that its application is limited to diminishing a witness's credibility. It is generally not intended to be used to augment or bolster credibility, for instance, by introducing prior consistent statements to show the witness has always told the same story. To allow such use for augmentation could risk circumventing the hearsay rule by bringing in prior statements for their truth value under the guise of supporting credibility. The Supreme Court's 2006 ruling also implicitly supports this restrictive view.

The issue of using prior consistent statements for "rehabilitation evidence" (回復証拠, kaifuku shōko)—i.e., to restore credibility after it has been attacked by an allegation of recent fabrication or improper motive—is a more complex area with ongoing debate, though majority opinion and some case law lean towards allowing it under specific, limited circumstances, distinct from the primary impeachment function of Article 328.

E. The Crucial Distinction: Impeachment, Not Substantive Proof

This is perhaps the most critical aspect of Article 328 for practitioners to grasp: a prior inconsistent statement admitted under this article is solely for impeachment. It cannot be used by the court (judges or lay judges) as substantive evidence of the truth of the facts asserted within that prior statement.

The Supreme Court affirmed this principle as early as February 17, 1953. For example, if a witness previously told police, "The getaway car was blue," but testifies in court, "The getaway car was red," the defense can introduce the prior "blue car" statement. However, this statement is only admissible to argue that the witness's current "red car" testimony is unreliable due to the inconsistency. The court cannot use the prior statement to conclude that the car was, in fact, blue. That would require separate, admissible substantive evidence. This limitation is a direct consequence of the hearsay rule, which Article 328 only partially pierces for the narrow purpose of assessing credibility.

III. The Act of "Using as Evidence": More Than Just Document Submission

The phrase "it may be used as evidence" (これを証拠とすることができる, kore o shōko to suru koto ga dekiru) in Article 328 implies an active process within the trial, not merely the passive submission of a document into the record after testimony is complete. Legal scholars and historical commentaries, including those by the Code's drafter Yokoi Daizo, indicate that the provision was intended to empower effective cross-examination by allowing the prior statement to be used during the questioning of the witness.

The objective is to:

  • Confront the witness with their own words in real-time.
  • Allow the court to observe the witness's demeanor and reaction when faced with the inconsistency.
  • Clearly highlight the contradiction for the trier of fact.

Simply filing the contradictory document later often lacks the same dramatic and persuasive impact as a live confrontation during cross-examination. Therefore, understanding how to properly present or "show" this prior statement to the witness in court becomes a critical procedural question, governed by the Criminal Procedure Rules.

IV. Criminal Procedure Rule 199-10: The Primary Procedural Tool for Presentation

Criminal Procedure Rule 199-10(1) provides a key avenue for presenting documents to a witness during examination:

"A party concerned may, when it is necessary in questioning a witness with regard to a document or object concerning its establishment, identity, or other similar matters, show the document or object to the witness."

Significantly, an attorney invoking this rule does not need prior permission from the presiding judge to show the document.

Application to Prior Inconsistent Statements:
The prevailing argument among many Japanese defense attorneys is that showing a prior inconsistent statement squarely falls under CPR 199-10. The reasoning is as follows:

  • Establishing "Identity" or "Similar Matters": When an attorney presents a prior statement (e.g., a signed police deposition), they are effectively asking the witness to confirm:
    1. "Is this document the statement you gave on [date]?" (Establishing its identity).
    2. "Does this statement, which bears your signature, contain the words '...'?" (Establishing its content, which is a "matter similar" to its identity as a record of their past assertion).
  • The Witness's Testimony "Helps the Document": In this context, the witness's in-court responses (confirming the signature, acknowledging the words, or reacting to the inconsistency) are what give the document its immediate relevance for impeachment. The document itself is being examined through the witness.
  • No Undue Influence for This Purpose: The rationale for not requiring judicial permission under CPR 199-10 is that when questioning about a document's authenticity or identity, showing it is usually essential, and the risk of unduly influencing the witness's substantive testimony about the underlying facts of the case is minimal for this specific purpose of authentication/identification.

"Omissions" (ketsuraku) as Impeachable Inconsistencies under CPR 199-10:
This framework also extends to situations where a witness testifies in court about an important fact that was conspicuously omitted from a comprehensive prior statement. If the prior statement was, for instance, a detailed account of an event where the now-asserted fact would logically have been mentioned if true and remembered, its absence can be treated as an inconsistency. To effectively impeach with an omission, the cross-examiner must first establish the importance of the omitted fact and why it would have been natural to include it in the prior statement. Then, using CPR 199-10, the prior statement can be shown to the witness to confirm the absence of the currently asserted detail, highlighting the "omission inconsistency."

V. Criminal Procedure Rule 199-11: Misunderstandings and Misapplications

A significant point of procedural debate and, at times, confusion in Japanese courtrooms revolves around CPR 199-11(1):

"A party concerned may, when it is necessary for refreshing the memory of a witness with regard to matters for which said witness's memory is unclear, show the witness a document (excluding a document recording a statement) or an object and question the witness, with the permission of the presiding judge."

The crucial elements are: (a) its purpose is memory refreshment, (b) it requires the judge's permission, and (c) its parenthetical explicitly excludes "a document recording a statement" (kyōjutsu o rokushu shita shomen o nozoku) from being shown for this specific memory-refreshment purpose.

Why CPR 199-11 is Generally Not the Correct Basis for Confrontational Impeachment:
Some judges occasionally suggest that showing a prior inconsistent statement is an act of "refreshing memory" and therefore falls under CPR 199-11, requiring their permission and running afoul of the exclusionary clause for recorded statements. However, defense counsel and many legal scholars argue this is a misapplication for several reasons:

  1. Different Purposes: The primary aim of confrontational impeachment is not to help the witness recall the past more clearly or to get them to adopt the prior statement as their refreshed, true memory. Instead, it is to demonstrate the fact of the contradiction itself to undermine their current testimony's credibility. The truth or falsity of the content of the prior statement is not the focus of the cross-examiner's assertion; the existence of the inconsistency is.
  2. Rationale for CPR 199-11's Exclusionary Clause: The exclusion of "documents recording a statement" for memory refreshment under CPR 199-11 is designed to prevent a specific kind of undue influence. If a witness's memory is genuinely hazy, showing them an official-looking police statement or deposition might lead them to abandon their own faint recollections and simply adopt the recorded narrative as their "refreshed" memory, even if it wasn't their true, independent recall. This is a valid concern when the goal is genuine memory refreshment for substantive testimony.
  3. Impeachment Doesn't Trigger the Same Concern: When showing a prior inconsistent statement under CPR 199-10 for confrontation, the attorney is not asking the witness to adopt its contents as their current, truthful testimony. In fact, the attorney is often implicitly (or explicitly) suggesting the prior statement might be more reliable than the current one precisely because it is different. The risk that CPR 199-11's exclusionary clause aims to prevent (undue adoption of a prior recorded narrative as current true memory) is not engaged in the same way during confrontational impeachment.

Therefore, the argument is that presenting a prior inconsistent statement for the purpose of establishing its existence and content for impeachment properly falls under CPR 199-10, which does not require judicial permission and is not barred by CPR 199-11's parenthetical exclusion regarding recorded statements used for memory refreshment.

VI. Criminal Procedure Rule 199-12: Clarifying its Inapplicability

For completeness, CPR 199-12 allows parties, with the judge's permission, to use diagrams, photographs, models, etc., to help a witness clarify their testimony. This rule is generally not pertinent to the specific act of presenting a witness's own prior written statement for the purpose of highlighting an inconsistency with their current oral testimony. The tools and purposes are distinct.

VII. Navigating the Hearsay Labyrinth: The Limited Purpose of Impeachment

It is essential to continuously circle back to the core principle: Article 328 CCP is a carefully circumscribed exception to the hearsay rule. Its sole function is to allow otherwise inadmissible prior statements to be considered for the narrow purpose of assessing the credibility of the witness's live, in-court testimony.

This means that even if a prior inconsistent statement is successfully introduced:

  • It does not "prove" that the events described in the prior statement actually happened.
  • The trier of fact must be careful not to treat the content of the impeaching statement as substantive evidence.
  • The only legitimate use is to decide whether the witness's current testimony is believable, given that they have said something different on a previous occasion.

This distinction is a constant challenge for legal practitioners and requires clear explanation and careful handling in court to ensure that evidence admitted for the limited purpose of impeachment is not improperly used to establish the truth of the matter asserted in the out-of-court statement.

VIII. Conclusion: Precision in Law and Procedure for Effective Impeachment

The use of prior inconsistent statements is a powerful technique in the Japanese criminal defense toolkit. However, its effectiveness hinges on a precise understanding and application of the governing legal framework. Article 328 of the Code of Criminal Procedure provides the substantive gateway, allowing such statements to be used for impeachment despite their hearsay nature. Concurrently, Criminal Procedure Rule 199-10 offers the primary procedural avenue for presenting these statements to a witness during cross-examination, focusing on the establishment of the statement's identity and content as a prelude to highlighting the inconsistency.

Defense attorneys must be adept at articulating this legal basis, particularly when facing procedural objections or judicial scrutiny that might erroneously attempt to shoehorn this practice into the more restrictive confines of rules designed for memory refreshment. A firm grasp of these legal foundations, coupled with the skillful execution of techniques like the 3C method, is crucial for ensuring that the truth-seeking function of cross-examination is robustly served in Japanese criminal trials.