The Tokyo High Court has overturned a lower court ruling that held former executives of Tokyo Electric Power Company Holdings Inc. (TEPCO) liable for damages over the disaster at the Fukushima Daiichi Nuclear Power Station, reversing an order for four executives to pay over 13 trillion yen (around $89.56 billion) to the company. Unless accountability for the disaster is clearly established, concerns about operating nuclear power plants in an earthquake-prone country like Japan cannot be dispelled.

The lawsuit was filed by shareholders of the company questioning the managerial responsibility of the executives. The point of contention was whether the tsunami that caused the accident could have been anticipated.

Nine years before the disaster, the government released a long-term assessment mentioning the possibility of an earthquake that could generate a massive tsunami occurring. Based on this evaluation, TEPCO's own estimates predicted a tsunami greatly exceeding the height of the plant grounds. The former managers, however, decided to verify the evaluation again with external experts, and postponed countermeasures.

The high court pointed out that the long-term assessment did not provide sufficient evidence and that there were differing opinions on the matter. It said that the only way to prevent the accident would have been to shut down the nuclear power plant, and that the lack of such a sense of urgency among executives couldn't be helped. It accordingly concluded that they did not neglect their responsibilities as directors.

This decision overturned a lower court ruling which had found the long-term assessment to be reliable and acknowledged that officials could have foreseen the tsunami. In a criminal trial of the former executives, the Supreme Court adopted the same line of thinking as that seen in the latest decision, and its ruling finding them not guilty was finalized.

However, once an accident occurs at a nuclear power plant, radioactive materials can spread over a wide area, causing enormous damage. The management of the operating power company must take all necessary measures to prevent such an event.

The high court added a supplementary opinion stating that if a nuclear accident were to occur now, given the experience of the Fukushima nuclear disaster, the directors would bear a heavier responsibility.

Nevertheless, officials must have known before the disaster that it is difficult to accurately predict a tsunami. Surely it is the responsibility of management to anticipate all risks and implement safer measures. Doubts remain about the high court's conclusion.

Fourteen years have passed since the nuclear disaster, but difficult-to-return zones remain in place, and many people continue to live as evacuees. There are no clear prospects for the decommissioning of the plant's reactors, and the final disposal site for soil removed during decontamination has not been decided.

TEPCO should face these issues head-on. Even if criminal and civil liabilities are avoided, the company cannot dodge its social responsibility for destroying people's lives and their hometowns.