Kenzo Koshijima, head of the plant at the time of the accident, received a three-year sentence, suspended for five years, and a fine of Yen 500,000 ($4200). The other five employees were handed suspended prison terms ranging between two and three years. JCO was fined Yen 1 million ($8500) for violating the Nuclear Reactor Regulation Law.
The defence attempted to argue that safety inspections by the Science and Technology Agency (now incorporated into the Education, Science and Technology Ministry) were flawed, thereby making the government partially responsible. Furthermore, the defence claimed that the former Power Reactor and Nuclear Fuel Development Corporation, now the Japan Nuclear Cycle Development Institute (JNC), had made unreasonable demands that put undue pressure on JCO. The panel of three judges rejected these arguments, saying the defence was trying to shift the blame. Chief judge Hideyuki Suzuki said the defendants acted illegally by not ensuring that the plant workers had received proper safety training.
JCO and the defendants indicated that they would not launch an appeal.