含羞草社区

Japan’s amended Whistleblower Protection Act is scheduled to come into force in December 2026. Among its various revisions, two changes are likely to have the most significant impact on corporate practice: first, shifting the burden of proof in civil proceedings; and second, introducing criminal penalties for retaliatory dismissal or disciplinary action.

Shift in burden pf proof

Under the amended act, where a whistleblower is dismissed or subject to disciplinary action within a year of reporting, it will be presumed in civil proceedings that such action is because of the whistleblowing. Unless the employer successfully rebuts this presumption, the dismissal or disciplinary action will be deemed invalid. This provision is a significant departure from prior practice, effectively lowering the evidentiary threshold for employees while imposing a substantial evidentiary burden on employers.

Criminal penalties for retaliation

The amendment also introduces criminal sanctions for dismissals or disciplinary measures taken in retaliation for whistleblowing. Individuals may face up to six months’ imprisonment or a maximum fine of JPY300,000 (USD1,880), while corporations may face fines of up to JPY30 million under dual liability provisions. The legislative objective is clear: strengthen deterrence against retaliation; enhance whistleblower protection; and promote the functioning of whistleblowing systems.

Strategic whistleblowing: Risks and warning signs

From a practical standpoint, it must be acknowledged that not all whistleblowing is motivated by a bona fide intent to remedy corporate wrongdoing. In some cases, employees – particularly those facing potential dismissal due to poor performance or misconduct – may strategically invoke whistleblowing mechanisms as a defensive measure.

Such employees may, for example, report alleged misconduct by supervisors or colleagues, and subsequently challenge adverse employment actions by relying on the above-mentioned statutory presumption.

In more contentious cases, they may also assert that disciplinary measures constitute unlawful retaliation, and seek to trigger criminal liability against corporate officers including HR and legal personnel.

Indicators of potentially abusive whistleblowing:

1. 1. Allegations concerning events that occurred more than one year earlier and were not previously regarded as problematic;
   2. Reports lacking factual credibility or substantiation; and
   3. Claims based on purely formal or technical regulatory violations that do not give rise to substantive compliance concerns.

Rebutting presumptions: Employer litigation strategies

Rebutting the statutory presumption under the amended act is likely to present a significant challenge in litigation. This is particularly so in Japan, where courts already interpret the validity of dismissals narrowly and impose a heavy burden of proof on employers. In light of these developments, companies should consider adopting the following risk mitigation measures:

1. 1. Contemporaneous documentation of pre-existing disciplinary considerations. Employers should ensure that any consideration of dismissal or disciplinary action is documented early, prior to any whistleblowing activity. Internal communications, such as reports from HR personnel to senior management, should be preserved.
   2. Comprehensive evidence collection. Employers should proactively gather objective evidence supporting disciplinary decisions including emails, contracts, internal records and witness statements.
   3. Structured decision-making records. The rationale for dismissal or disciplinary action should be clearly documented, with reference to specific facts and legal grounds.
   4. Engagement of external counsel. Where appropriate, companies should seek independent legal opinions to validate the lawfulness of proposed disciplinary measures.
   5. Separation of functions (“firewall” mechanisms). To avoid allegations of retaliatory intent, companies should establish clear separation between personnel responsible for investigating whistleblowing reports and those for making disciplinary decisions. This may involve dividing roles within HR or outsourcing investigations to legal departments or external advisers.

Japan whistleblower reforms: Governance, litigation risks

The 2025 amendment to Japan’s Whistleblower Protection Act marks a significant strengthening of protections, with far-reaching implications for corporate governance and employment practices.

While these reforms aim to foster transparency and accountability, they also introduce new litigation and compliance risks, particularly in cases involving potentially strategic or abusive whistleblowing.

Accordingly, companies operating in Japan should proactively review and enhance their internal procedures to ensure both compliance with the amended law and the defensibility of disciplinary decisions in an increasingly complex legal environment.

Kengo Nishigaki is a representative partner at GI&T Law Office in Tokyo

GI&T Law Office
23F Marunouchi Kitaguchi Building,
1-6-5 Marunouchi, Chiyoda-ku,
Tokyo 100-0005, Japan

T: +81 3 6206 3283
E: kengo.nishigaki@giandt-law.com