Japan has released a guideline that states self-driving vehicles cannot be tested on public roads without the presence of a human driver.

According to the National Police Agency, this move has been taken to ensure road safety.

The release of the guideline is expected to bolster the process of testing self-driving cars.

"The police agency expects to set up a panel this year to look into issues such as who should be legally responsible if there is an accident."

The NPA also urged for the use of black boxes on autonomous vehicles being tested.

These vehicle drive recorders can help in ascertaining causes of the accidents, which in turn helps in taking preventive measures.

The police agency expects to set up a panel this year to look into issues such as who should be legally responsible if there is an accident, how to adapt the driver's license to the new driveless vehicle future and what kind of measures are needed to prevent cyberattacks.

The government has come up with a classification system.

As per this system, a self-driving vehicle comes under level 4 if it can carry out all safety-critical driving functions autonomously.

Vehicles with limited self-driving automation come under level 3. In this classification, a driver ought to have control of the vehicle when it is necessary though maneuvering can be autonomous.

Level 2 is aplicable if several functions such as control, acceleration and steering are automated.

A vehicle comes under level 1 if only some of its functions are automated.