When Can Only Part of a Japanese Law Be Struck Down? The Doctrine of "Partial Unconstitutionality"

When a Japanese court finds that a statute conflicts with the Constitution, it does not always result in the entire law being nullified. The judiciary possesses a more nuanced tool known as "partial unconstitutionality" (部分違憲 - bubun iken, also referred to as 一部違憲 - ichibu iken, or partial invalidity, 一部無効 - ichibu mukō). This doctrine allows a court to invalidate only the specific problematic portions or applications of a statute while leaving the remainder intact and enforceable. This approach reflects a principle of judicial restraint and an effort to respect legislative intent as much as possible, while still providing a remedy for constitutional violations. The Supreme Court of Japan has increasingly utilized this technique in significant unconstitutionality rulings in recent years, making it a crucial concept for understanding the practical impact of constitutional review.

Defining Partial Unconstitutionality and its Manifestations

Partial unconstitutionality is a specific form of statutory unconstitutionality (hōrei iken) where a court identifies a constitutional flaw that affects only certain aspects of a law. This can be conceptualized in two main ways:

1. Literal Partial Unconstitutionality (文言上の部分違憲 - Mongonjō no Bubun Iken or 量的部分違憲 - Ryōteki Bubun Iken):
   This involves a finding that specific words, phrases, clauses, or subsections within a statute are unconstitutional. The offending text is, in effect, judicially excised, while the rest of the statutory provision or the law as a whole continues to operate.
   While the Overseas Japanese Citizens Voting Rights Case (Zaigai Kokumin Senkyoken Hanketsu), decided by the Supreme Court's Grand Bench on September 14, 2005 (Heisei 17), is a complex example that involved finding an omission unconstitutional, a simpler analogy (though concerning a Cabinet Order rather than a statute directly enacted by the Diet) can be found in a Supreme Court (First Petty Bench) ruling on January 31, 2002 (Heisei 14). This case dealt with a Cabinet Order under the Child Rearing Allowance Act. The Court invalidated a specific exclusionary phrase within the Order – "(excluding children recognized by the father)" – from the definition of eligible children. The effect of striking this phrase was to broaden the eligibility for the allowance to include children recognized by their fathers but born out of wedlock, a group previously excluded by that text.
2. Semantic Partial Unconstitutionality (意味上の部分違憲 - Imijō no Bubun Iken or 質的部分違憲 - Shitsuteki Bubun Iken):
   This form does not target specific textual elements but rather finds a particular meaning, scope of application, or an unstated assumption within a statutory provision to be unconstitutional. The statutory text itself may remain unchanged, but its operative effect is judicially narrowed or altered for a certain category of cases.
   The Postal Law Unconstitutionality Case (Yūbinhō Iken Hanketsu), a Grand Bench decision of the Supreme Court on September 11, 2002 (Heisei 14), provides a clear illustration. Article 68 of the Postal Law (as it then stood) significantly limited the state's liability for damages arising from the loss or damage of mail, restricting claims to specific, enumerated circumstances. The Supreme Court did not strike down Article 68 entirely. Instead, it found that:
   • For registered mail, the part of the provision's meaning that exempted the state (then operating the postal service) from liability for loss or damage caused by the intentional or grossly negligent acts of postal employees was unconstitutional, violating Article 17 of the Constitution (the right to sue the state for redress).
   • Similarly, for special delivery mail, the part of the provision's meaning that exempted the state from liability for loss or damage caused by simple negligence was also deemed unconstitutional.
     These distinctions based on the type of mail and the level of culpability were not explicitly delineated in the text of Article 68 itself but represented judicially identified unconstitutional applications or meanings embedded within the general rule of limited liability.

While these two types are distinguished conceptually, legal commentators sometimes note that the practical difference in outcome or the clarity of the distinction may not always be paramount.

The Rationale and Significance of Partial Unconstitutionality

The doctrine of partial unconstitutionality serves several important functions within the Japanese system of judicial review:

• Minimizing Judicial Interference with Legislative Authority: By invalidating only the offending part of a statute, courts avoid overstepping their role and show deference to the legislative branch. It presumes that the legislature would have intended the constitutional portions of the law to remain in effect.
• Promoting Legal Stability: Wholesale invalidation of a statute can create a legal vacuum and disrupt established social or economic arrangements. Partial unconstitutionality helps to maintain legal continuity by preserving the valid aspects of the law.
• Providing Tailored and Effective Remedies: It allows courts to provide specific relief to litigants whose rights have been infringed by an unconstitutional aspect of a law, without unsettling the entire legislative scheme. It offers a more precise and proportionate remedy.

Distinguishing Partial Unconstitutionality from Related Judicial Doctrines

It is important to differentiate partial unconstitutionality from other judicial techniques used to address constitutional concerns:

1. Constitutionally Limited Interpretation (Gōken Gentei Kaishaku):
   • Similarity: Both doctrines aim to resolve a conflict between a statute and the Constitution by neutralizing the unconstitutional aspect of the law's reach.
   • Difference: The crucial distinction lies in the outcome for the statute itself. With partial unconstitutionality, a segment of the law (whether textual or semantic) is declared unconstitutional and void. In contrast, with constitutionally limited interpretation, the court construes the ambiguous or overly broad language of the statute narrowly so that, as interpreted, the entire statute is deemed constitutional and remains fully in effect. The former involves a finding of partial invalidity; the latter involves a validating interpretation.
   • For instance, the Hiroshima City Ordinance Regulating Motorcycle Gangs (Bōsōzoku) Case (Supreme Court, Third Petty Bench, September 18, 2007 (Heisei 19)) saw the majority adopt a constitutionally limited interpretation, narrowing the scope of regulated persons from "any person" to "motorcycle gangs and similar groups" to avoid constitutional issues of vagueness and overbreadth. An alternative approach, had the Court found such an interpretation unfeasible, might have been to declare the ordinance partially unconstitutional insofar as it applied to persons other than clearly defined motorcycle gangs.
2. As-Applied Unconstitutionality (Tekiō Iken):
   • Similarity: Both address situations where a law's application in specific contexts is constitutionally problematic.
   • Difference: While the lines can sometimes blur, contemporary legal scholarship tends to view "as-applied unconstitutionality" as a finding that a law is unconstitutional specifically in its application to the unique facts of the case before the court, often resulting from a review focused on adjudicative facts. "Partial unconstitutionality," on the other hand, frequently emerges from a more general (or facial) assessment of the law's structure or content, leading to the invalidation of a defined category or type of application, often based on legislative facts.
   • An "as-applied" ruling is typically understood to invalidate the law only for that particular instance or for instances with virtually identical facts. "Partial unconstitutionality," by defining a segment of the law (textual or semantic) as void, generally has a broader effect, nullifying that aspect for an entire class of applications. The first instance judgment in the Saruhashi Case, which identified a specific type of public servant and political activity for which the law was unconstitutional, though formally an "as-applied" ruling, had substantive characteristics akin to a finding of partial unconstitutionality due to its categorical nature.

Conditions and Limitations for Employing Partial Unconstitutionality

The remedy of partial unconstitutionality is not universally available. Its application is subject to important conditions and limitations:

1. Feasibility of Constitutionally Limited Interpretation: Consistent with the principle of judicial restraint and the desire to avoid constitutional questions where possible, if a statute can be rendered constitutional through a reasonable and textually plausible limiting interpretation, that method is generally preferred over finding any part of the law unconstitutional. Partial unconstitutionality is typically considered when such a saving interpretation is not feasible.
2. Clear Delineation of the Unconstitutional Part (違憲部分の明確な定式化 - Iken Bubun no Meikakuna Teishikika): A fundamental prerequisite is that the court must be able to clearly and precisely identify and articulate the specific portion, meaning, or application of the law that is unconstitutional. If the unconstitutional element cannot be clearly demarcated, a finding of partial unconstitutionality would create unacceptable legal uncertainty, fail to provide adequate guidance to the legislature and public, and risk inadvertently invalidating constitutionally sound applications.
3. The Crucial Test of Severability (法令の可分性 - Hōrei no Kabunsei):
   This is often the most critical and complex condition. The unconstitutional part of a statute must be "severable" from the rest. Severability means two things:
   • The remaining valid portions of the statute must be capable of standing alone and functioning meaningfully as a coherent legislative scheme.
   • Excising the unconstitutional part must not fundamentally alter the core legislative purpose or create a result that the legislature would not have intended. The court, in effect, asks whether the legislature would have enacted the valid portions even without the unconstitutional part.
     If the unconstitutional and constitutional parts are so inextricably intertwined in purpose and function that they cannot be separated without destroying the legislative scheme or creating an absurd result, then the entire statute (or at least the relevant overarching provision) may have to be declared unconstitutional.

A Special Challenge: Partial Unconstitutionality and Beneficial Statutes (Entitlements)

Applying partial unconstitutionality becomes particularly sensitive when dealing with beneficial statutes—those that grant entitlements, benefits, or qualifications—and the constitutional flaw lies in a restrictive condition or an exclusion. If a court strikes down such a restrictive condition, it can appear as though the court is effectively creating a new, broader entitlement that the legislature itself did not enact, thereby encroaching upon the legislative domain.

The Nationality Law Unconstitutionality Case (Kokusekihō Iken Hanketsu), a Grand Bench decision of the Supreme Court on June 4, 2008 (Heisei 20), starkly illustrates this challenge. The former Article 3(1) of the Nationality Law allowed a child born out of wedlock to a Japanese father and a non-Japanese mother to acquire Japanese nationality by notification only if two conditions were met: (1) the Japanese father acknowledged paternity, AND (2) the child's parents subsequently married. The Supreme Court found the second condition (parental marriage) to be an unconstitutional discrimination based on birth status, violating Article 14 of the Constitution (equality under the law). It then declared this marriage requirement—a specific meaning or condition within the provision—partially unconstitutional. Consequently, children who met only the first condition (paternal acknowledgment) could acquire nationality by notification, even if their parents never married.

This ruling sparked debate. Did the Court merely remove an unconstitutional impediment to an existing entitlement, or did it effectively legislate a new category of entitlement (nationality for non-marital children acknowledged after birth whose parents did not marry), a category the Diet had not previously established? The Supreme Court's majority justified its approach by arguing that applying the law with only the acknowledgment requirement remaining was consistent with a rational legislative intent underlying the Nationality Law's broader aim of linking nationality to substantial ties with Japan. However, dissenting opinions contended that this was an impermissible act of judicial legislation, arguing that the original provision was an indivisible set of requirements for a specific status (akin to "quasi-legitimation"), and invalidating one part created a legislative gap that only the Diet could properly fill.

The feasibility of partial unconstitutionality in such beneficial statute contexts often hinges on whether the court can convincingly demonstrate that the remaining statutory framework reflects a severable, rational, and intended legislative scheme, rather than one judicially constructed. If a law clearly sets out a general principle and an exception, and only the exception is found unconstitutional, it is generally easier to apply the remaining general principle.

Conclusion

The doctrine of partial unconstitutionality is a vital and increasingly prominent instrument in the toolkit of the Japanese constitutional judiciary. It enables courts to address constitutional infirmities in legislation with precision, balancing the imperative to uphold constitutional norms against the principles of judicial restraint, respect for legislative authority, and the maintenance of legal stability. By allowing for the targeted invalidation of only the flawed components or applications of a statute, it avoids the often disruptive consequences of wholesale statutory nullification.

However, the application of this doctrine is not without its complexities. It is governed by stringent conditions, most notably the requirement of clear delineation of the unconstitutional element and the critical principle of severability. These conditions aim to ensure that courts are meticulously remedying specific constitutional violations rather than improperly engaging in judicial legislation. As Japanese constitutional law continues to evolve, the nuanced application of partial unconstitutionality will undoubtedly remain a key area of judicial and academic focus.