The Tokyo High Court is scheduled to hand down a ruling Wednesday on three former executives of Tokyo Electric Power Company over the 2011 accident at the utility's Fukushima Daiichi nuclear power plant.
Former TEPCO chairman Katsumata Tsunehisa and former vice presidents Takekuro Ichiro and Muto Sakae were indicted in 2016 on charges of professional negligence resulting in death and injury by court-appointed lawyers acting as prosecutors.
The indictment was based on a decision by a prosecution inquest panel composed of randomly chosen citizens.
The prosecution alleged the three former executives were responsible for the deaths of 44 people, including patients at a hospital in Fukushima Prefecture, during evacuations after the nuclear accident.
A lower court had previously acquitted them, saying they could not have foreseen risks that would have required the suspension of operations at the nuclear plant. The plaintiffs' lawyers then filed an appeal.
The focus of the trial is the reliability of a long-term assessment of possible seismic activities issued by a government panel in 2002.
In the appeals court hearing, the court-appointed lawyers acting as prosecutors argued the long-term evaluation was clearly reliable, and the three defendants could have foreseen the possibility of tsunami more than 10 meters high.
They said the former executives were obligated to build seawalls and take steps to keep water out of reactor buildings and other structures.
The defendants denied the charges, saying the long-term assessment lacked scientific credibility.
The assessment was recognized as reliable in a civil court ruling issued after the lower court acquittal.
In that ruling last July, the Tokyo District Court ordered them and another defendant to pay more than 13 trillion yen, or about 101 billion dollars, in compensation.