Active Cyber Defense Japan Law 2025-2026: Complete Guide
Corporate LawLast updated: 2026-04-062 min readLawyer-Reviewed

Active Cyber Defense Japan Law 2025-2026: Complete Guide

Key Takeaways

  • The Cyber Response Capability Enhancement Act legalizes "active cyber defense" from October 2026
  • Critical infrastructure operators must report cyber incidents to the government
  • Three pillars: public-private cooperation, communications intelligence, and attack server neutralization
  • An independent oversight commission monitors the balance with communications secrecy
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Overview of the Active Cyber Defense Act

The Cyber Response Capability Enhancement Act (commonly called the Active Cyber Defense Act), scheduled for enforcement in October 2026, fundamentally strengthens Japan's national cybersecurity posture. It shifts from a reactive approach to proactive defense that aims to prevent attacks before they occur.

The act was passed during the 2025 ordinary Diet session and is scheduled for implementation within 18 months of promulgation.

Three Pillars

1. Strengthened Public-Private Cooperation

Critical infrastructure operators (electricity, telecommunications, finance, transportation, healthcare) face new obligations:

  • Mandatory incident reporting: Prompt government notification of significant cyberattacks
  • Information sharing: Structured sharing of attack methods and vulnerability data
  • Covered entities: Telecom carriers, power companies, banks, railways, medical institutions

2. Communications Intelligence

The government gains authority to analyze communications metadata (IP addresses, connection destinations) to detect cyberattack indicators:

  • Communications content is excluded (protecting constitutional secrecy of communications)
  • Analysis limited to metadata only
  • Monitored by the independent Cyber Communications Information Oversight Commission

3. Attack Server Neutralization

The state gains authority to access and neutralize (e.g., remove malware from) attack-origin servers:

  • Executed by police and Self-Defense Forces
  • Requires prior review by an independent body
  • Covers both domestic and foreign servers
  • Post-hoc review permitted in emergencies

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What Businesses Need to Do

Critical Infrastructure Operators

ActionDetails
Incident reportingEstablish 24-hour initial response capability
Information sharingJoin industry ISACs and sharing organizations
Security standardsComply with government-set criteria

General Businesses

Even companies outside critical infrastructure should consider:

  • Strengthening security against supply chain attacks
  • Developing and regularly drilling incident response plans
  • Meeting security requirements if partnering with critical infrastructure entities

Impact on Individuals

No direct obligations are imposed on individuals. However, the government's use of communications metadata has prompted privacy discussions. Safeguards include independent oversight and the exclusion of communications content.

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This article provides general legal information and does not constitute legal advice. For specific legal issues, please consult with a qualified attorney.

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