A Japanese court ruled on Thursday that three former executives of the Tokyo Electric Power (TEPSCO) should not be considered criminally negligent for the 2011 nuclear disaster at the Fukushima plant.

Japanese prosecutors accused TEPCO former-Chairman Tsunehisa Katsumata (79), former vice presidents Sakae Muto (69), and Ichiro Takekuro (73) of not adequately preparing their infrastructure to withstand a tsunami exceeding 10-meters. The prosecution argued that there were studies warning management in advance of the potential impact of tsunamis.

The court accepted the argument that the executives were not involved in day-to-day operations, trusted those managing nuclear facilities, and could not be held criminally responsible.

The prosecution had initially refused to try the case, citing insufficient evidence, forcing state lawyers to take over the case. The plaintiffs are expected to appeal the Tokyo District Court decision. The lawyer representing the 5,700 Fukushima residents said on Thursday that he expect the legal battle to last about a decade.

The 2011 9.0 earthquake triggered a massive tsunami that devastated the Fukushima Daiichi Nuclear Power Station, causing three of its six reactors to meltdown, releasing radiation over a wide area. 20,000 people died of the natural disaster and more than 160,000 were forced to flee their homes. 6,000 of the surviving residents filed a criminal complaint with the objective of closing nuclear plants.