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15 Oct 2004

Business & Human Rights Resource Centre

Chisso Corporation lawsuit (re Minamata disease)

Status: CLOSED

Date lawsuit was filed
15 Oct 2004
Location of Filing: Japan
Location of Incident: Japan
Type of Litigation: Domestic


Chisso Japan


Snapshot: In 1974, victims of Minamata disease won their lawsuit against Chisso Corportation, the Japanese Government, and the Kumamoto Prefecture over the health impact of the wastewater from the company's chemical factory. that contained mercury. In 1995, the Japanese Government provided a settlement for Japanese workers who had not contracted Minamata disease, most workers took the settlement. However, the Minamata Disease Kansai Patients Association refused the settlement and pursued litigation. The Patients Association won their lawsuit at the Osaka High Court and the ruling was affirmed by the Supreme Court in 2004. Liability has been extended to the Kumamoto Prefecture for other cases as well.

Between 1938 and 1968, the wastewater from Chisso Corporation’s chemical factory in the Kumamoto district of Japan flowed into Minamata Bay.  This wastewater contained mercury.  In 1956, a doctor at Chisso’s factory reported increased cases of individuals with nervous system damage, officially recognising the existence of what came to be known as Minamata disease.  Symptoms of the disease include seizures, spasms, loss of motor control, numbness, paralysis, sensory impairment and, in extreme cases, death.  The disease was caused by mercury poisoning occurring through the food chain; fish in the bay contained concentrated mercury toxins and when caught and consumed, the toxins were assimilated into the bodies of the people who ate them.

Minamata victims launched numerous legal actions against Chisso Corporation, the Japanese Government and Kumamoto prefecture.  A group of Minamata victims filed a lawsuit in 1969 against Chisso alleging corporate negligence.  The trial lasted almost four years.  The court ultimately ruled in favour of the plaintiffs and ordered Chisso to pay compensation to the victims.  As the number of victims continued to increase, the Japanese Government adopted a certification process whereby people were officially certified as suffering from Minamata disease based on a characteristic combination of symptoms. 

A former president of Chisso and a supervisor of the Minamata factory faced criminal proceedings in 1979 for causing death and serious bodily harm.  In 1979, they were sentenced to two years in prison; these decisions were upheld by the High Court and Supreme Court.  In 1995, the Japanese Government proposed a settlement plan to those who had not been certified with Minamata disease in exchange for them dropping all related litigation.  Many victims accepted this settlement.

The Minamata Disease Kansai Patients Association refused to drop their case.  In 1982, the Association sued Chisso Corporation, the Japanese Government and Kumamoto prefecture demanding recognition as Minamata disease victims and compensation for the damages they suffered.  The Osaka District Court in July 1994 ruled that neither the government nor the prefecture was responsible for the damage to the victims.  The plaintiffs appealed this decision in Osaka High Court which overturned the lower court’s decision and found that the defendants had failed to exercise their regulatory authority as required by water quality legislation and the Fisheries Coordination Regulation of Kumamoto prefecture.  This decision was appealed by the defendants to the Supreme Court which in October 2004 upheld the decision of the High Court.  The Court found that by November 1959, three years had already passed since the official discovery of Minamata disease and despite this development, the authorities had not prevented the residents from consuming contaminated fish and shellfish from the bay.  The Court found that the plaintiffs were entitled to receive compensation for the damage they suffered.

In April 2010, the Japanese Government approved a measure to provide compensation to uncertified sufferers of Minamata disease.  This measure will allow for a lump sum payment to these uncertified sufferers who have not joined a lawsuit against the government or Chisso.  Chisso will pay ¥3.15 billion to three organizations of the uncertified disease sufferers who have not joined a lawsuit.

On 31 March 2014, the Kumamoto District Court ordered the state, the Kumamoto Prefectural Government and Chisso to pay ¥106 million in damages to three uncertified sufferers who sued them. In that case, the defendants denied liability for the allegations that the plaintiffs had contracted Minamata disease due to mercury intake.

- “Relief for unrecognized Minamata victims OK'd”, Yomiuri Shimbun, 16 Apr 2010
- “Japan to Compensate More Victims of Mercury Disaster”, AFP, 3 Jul 2009
- “Court orders damages paid to Japan poisoning victims”, Kozo Mizoguchi, Associated Press, 16 Oct 2004
- “Victims Not Ready to Close Books on Minamata Saga”, Sonni Effron, Los Angeles Times, 10 Aug 1997
- “JAPAN - Victims of Mercury Poisoning Settle”, Los Angeles Times, 23 May 1996
- “Japan Mercury Victims Get Court Award”, Los Angeles Times, 27 Nov 1993
- “30 Years after Mercury Poisoning at Minamata - Ecological Disaster at Japan Village Leaves Legacy of Suffering”, Michael Weisskoff, Washington Post, 10 May 1987

- Ministry of the Environment, Government of Japan: Minamata Disease - The History and Measures, 2002
- Soshisha (the Supporting Center for Minamata Disease): Brief Chronology of the Minamata Disease Incident and Activities of the Soshisha

- Xs V Japan & Kumamoto Prefecture, Supreme Court of Japan, 15 Oct 2004