The government is considering legislation that would allow a 20-year prison term for people who deliberately design or construct illegal buildings whose collapse leads to fatalities, according to government sources.
A maximum 15-year term is being considered for designers, structural engineers, developers and builders who build properties whose collapse lead to injury, the sources said.
The current Building Standard Law does not include prison terms for violators whose conduct causes death or injury.
But proving that a building has collapsed due to illegal construction would be difficult, making it uncertain whether such punishment will be included in a bill to be presented to the Diet during the current session running through June 18.
Under current law, the heaviest punishment for building a structure that doesn't meet safety codes, regardless of collapse, is a 500,000 yen fine.
The government wants to boost the fine to a maximum 3 million yen along with a maximum three years in prison, the sources said.
The penalties are being discussed by the Land, Infrastructure and Transport Ministry in response to the fabrication of earthquake-resistance data by disqualified building structural engineer Hidetsugu Aneha.