On September 27, 2023, the Osaka District Court issued its decision in the first of four class action lawsuits filed by around 1,800 plaintiffs. All of these people were denied relief under the Minamata Disease Special Measures Law, which allows for lump-sum payments and other benefits if certain standards are met.

Under the law, the government defined "boundaries" for qualification based on "geographical area affected," "age," and "time of contraction." The plaintiffs in the Osaka action were among those whose compensation claims were denied due to these stringent criteria.

Despite exhibiting certain indications of Minamata illness, the plaintiffs' original residences were beyond the target region. Or, in other situations, Minamata disease was discovered after the government's deadline for diagnosis.

In March 2024, a ruling on a part of the Kumamoto litigation, which involves 1,405 plaintiffs, is expected. There are also two more active lawsuits in Niigata (151 plaintiffs) and Tokyo (75 plaintiffs).