What Is Level 4 Autonomous Driving?
Autonomous driving technology is classified into six levels (Level 0 through Level 5) based on the SAE International standard. Level 4 (High Driving Automation) means the system handles all driving tasks without any human intervention within a defined Operational Design Domain (ODD).
| Level | Name | Who Drives | Legal Status in Japan |
|---|---|---|---|
| Level 1-2 | Driver Assistance | Human | Driver bears responsibility under the Road Traffic Act |
| Level 3 | Conditional Automation | System (partial human) | Addressed by the 2020 amendment (Article 75-2 et seq.) |
| Level 4 | High Automation | System | Codified as "Specified Autonomous Driving" by the 2023 amendment |
| Level 5 | Full Automation | System | Not yet addressed (under policy discussion) |
The "Specified Autonomous Driving" System Under the Revised Road Traffic Act
Legislative Background
The revised Road Traffic Act (Act No. 32 of 2022) was enacted in April 2022 and took effect on April 1, 2023. The revision added provisions on "Specified Autonomous Driving" (Articles 75-12 through 75-28) to the Road Traffic Act.
Legal Definition
Article 2(1)(xvii)-2 of the revised Road Traffic Act defines "Specified Autonomous Driving" as:
> Operating an automobile equipped with an automated driving device on a road, using that device within its designated conditions of use, in a state where no driver is present.
Unlike Level 3, this system presupposes operation without a driver inside the vehicle.
The Permit System
To conduct Specified Autonomous Driving, a permit from the prefectural Public Safety Commission is required (Article 75-12).
| Item | Details |
|---|---|
| Applicant | The entity intending to conduct Specified Autonomous Driving |
| Authority | The Public Safety Commission of the prefecture covering the operational area |
| Key requirements | Designated routes/areas, safety measures, remote monitoring infrastructure |
| Remote monitor | Mandatory appointment of a Specified Autonomous Driving Supervisor (Article 75-23) |
| Accident response | The operator must report and provide rescue assistance (Article 75-24) |
Remote Monitoring and the Specified Autonomous Driving Supervisor
Because no driver is present in the vehicle for Level 4 operation, the remote monitor (Specified Autonomous Driving Supervisor) plays a critical role. This supervisor continuously monitors the vehicle's driving status remotely and takes measures to bring the vehicle to a safe stop in the event of an anomaly (Article 75-23). Notably, a driver's license is not required for this role, though completion of a training course designated by the Public Safety Commission is mandatory.
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Try for free →Amendments to the Road Transport Vehicle Act
The Road Transport Vehicle Act was also amended to accommodate Level 4. A 2020 revision explicitly added "automated driving devices" (Article 41(2)) to the scope of safety standards. In coordination with the 2023 Road Traffic Act amendments, type approval and inspection standards for Level 4 vehicles were established.
Automated driving devices installed in vehicles must receive type designation from the Minister of Land, Infrastructure, Transport and Tourism. Cybersecurity and software update management are also included in safety standards (compliant with UN Regulation WP.29).
Liability for Accidents and Compulsory Auto Insurance
Civil Liability
The following legal frameworks govern civil liability for Level 4 autonomous driving accidents:
| Liable Party | Legal Basis | Scope |
|---|---|---|
| Vehicle owner (operational provider) | Automobile Liability Security Act, Art. 3 | Operational provider liability (near strict liability) |
| Specified Autonomous Driving operator | Road Traffic Act Art. 75-24, Civil Code Art. 709 | Tort liability for breach of safety management duty |
| Vehicle manufacturer | Product Liability Act, Art. 3 | Product liability based on defects in the automated driving device |
Application of the Automobile Liability Security Act (ALSA)
Critically, the ALSA applies to Level 4 autonomous driving. The "operational provider" liability under ALSA Article 3 is imposed on those who "provide a vehicle for their own operational use," which includes owners and operators of autonomous vehicles.
The government has made clear its policy to extend compulsory automobile liability insurance (CALI) to Level 4, ensuring no gap in victim relief. For accidents caused by hacking of automated driving devices, relief through the government indemnity program (ALSA Article 72) is also under consideration.
Criminal Liability
Because no driver is present in Level 4 vehicles, traditional criminal liability for "drivers" (negligent driving causing death or injury) does not directly apply. Instead, the application of professional negligence causing death or injury (Penal Code Article 211) to the Specified Autonomous Driving operator who fails in safety management duties is being discussed.
Deployment Status as of 2026
Eiheiji Town, Fukui Prefecture: Japan's First Level 4 Approval
In May 2023, the "ZEN Drive" service in Eiheiji Town, Fukui Prefecture, obtained Japan's first Level 4 Specified Autonomous Driving permit. Low-speed electric carts operating at 12 km/h or below run unmanned under remote supervision along an approximately 2 km pedestrian path. As of 2026, the service has logged tens of thousands of trips with no serious accidents reported.
Demonstration Tests in Tokyo
From 2025 through 2026, multiple companies have been conducting Level 4 autonomous bus demonstration tests in Tokyo's waterfront areas and designated zones. The Tokyo Metropolitan Government aims for social implementation during fiscal year 2026, working to expand routes and resolve regulatory challenges.
Other Regions
Level 4 demonstration tests are also underway in depopulated rural areas, airports, and port districts nationwide. Expectations are growing for autonomous driving as a solution to regional transportation challenges in collaboration with local governments.
Challenges Toward Full Automation (Level 5)
Level 5 (Full Driving Automation) — where the system drives in any situation regardless of location or conditions — is not yet addressed by current law. Key challenges for future legislation include:
| Challenge | Details |
|---|---|
| Eliminating the ODD | Level 5 removes geographic limitations, requiring fundamental revision of the permit system |
| Ultimate liability allocation | Redefining responsibility among manufacturers, operators, and owners |
| International harmonization | Participation in UN/WP.29 international standard development and domestic implementation |
| Cybersecurity | Strengthening legal responses to remote control and hacking risks |
| Legal framework for ethical AI decisions | Developing guidelines for AI decision-making in accident avoidance scenarios |
The government has indicated it will pursue phased legislative reform based on the "Outline for Institutional Development on Autonomous Driving" formulated in 2025.
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*Houritsu no Mikata Editorial Team | Published April 29, 2026*
