Plaintiffs demanding a halt to Hokkaido Electric Power Co.’s Tomari nuclear plant are celebrating a major victory that came more than 10 years after they first launched their legal battle.

But while some think this could mark a turning point in how courts handle stalled lawsuits against nuclear plants, the plaintiffs’ long fight also appears not to be over.

The utility is vowing to appeal and pressure is increasing within the government to step up nuclear power generation amid rising fuel costs.

The Sapporo District Court ruled on May 31 that the plant is not equipped with sufficient safeguards against the most powerful tsunami that could hit it, marking the country's first court decision to pull the plug on a nuclear plant based on the threat posed by tsunami.

“The decision was only appropriate and easy to understand,” said Morihiro Ichikawa, who headed a group of lawyers representing the plaintiffs at a news conference after the court handed down its verdict. “The court heard our plea to stop the restart due to safety concerns.”

The lawsuit, filed in 2011 after the Fukushima nuclear disaster struck earlier that year, dragged on as Hokkaido Electric repeatedly failed to argue its case with credible documentation. The proceedings coincided with an ongoing safety review of the plant by the government’s Nuclear Regulation Authority.

The court abruptly ended the hearings in January, despite the utility’s earlier pledge that it would prove the plant’s safety by February. It concluded the company was unlikely to do so in a timely manner, if ever, given how previous hearings had unfolded.

Presiding Judge Tetsuya Taniguchi said in the ruling, “It was difficult to justify continuing court hearings, as it was unclear whether and when Hokkaido Electric would ever finish substantiating its assertions.”

Ichikawa said the manner in which the district court handled the case could have a significant impact on other lawsuits against nuclear plants.

“The court issued the ruling, instead of the NRA, as the court believed it should not wait any longer,” Ichikawa said.

“There are a number of lawsuits that the court stalled on, citing the pending NRA safety screenings,” he said. “But the latest decision showed that the court can close the case and deliver a ruling if its safety has not been established.”

Although there were three points of contention in the case, the court ruling was delivered based on the decision that the nuclear plant, which has three reactors, does not have a sea wall that can likely protect it from the most powerful tsunami expected there.

The court ruled the utility has yet to prove that the existing sea wall and a new one to replace it would meet the new safety standards adopted in 2013.

The NRA had pointed out the possibility that the sea wall, which was built in 2014 and stands 16.5 meters from the sea surface, sits on ground that could give way in an earthquake.

In response, Hokkaido Electric announced a plan to build a new sea wall.

But the court decided that the company had not backed up its argument that the ground on which the new sea wall will be built is solid. On top of that, details about the wall’s structure and other key aspects about it remain unclear.

As of April, 34 lawsuits are being fought over nuclear plants at district courts and high courts across the country, according to the national network of lawyers for lawsuits aimed at moving away from reliance on nuclear power.

Hokkaido Electric released a statement on May 31 saying it will "promptly start with procedures to appeal” the decision.

“We find it extremely regrettable and unacceptable that the court did not show understanding to our arguments,” it read.

The district court decision comes as calls are growing within the government for boosting supply from nuclear plants in light of a steep surge in fuel prices following Russia’s invasion of Ukraine as well as the global trend toward decarbonization. 

Prime Minister Fumio Kishida is expected to push for the “maximum use” of nuclear plants in his economic policy, given the government’s pitch that nuclear energy is a “stable source of power.”

But the Sapporo District Court’s ruling highlights the legal risks facing nuclear plant operators in a country prone to powerful earthquakes, tsunami and volcanic eruptions.

Some reactors were unable to go back into operation for up to two years due to court injunctions after plaintiffs sought their suspensions, citing risks related to natural disasters, a lack of workable evacuation plans and inadequate safeguards.

According to the government’s basic energy plan, approved in October, nuclear power is expected to account for 20-22 percent of Japan’s energy output in fiscal 2030.

That means all 27 reactors that utilities are seeking to restart through applications to the NRA would have to go back online. But so far, only 10 have.