The Osaka High Court overturned on Thursday a 2010 ruling that backed an 86-year-old woman's claim that she be granted public aid as a victim of Minamata disease.
A focal point in the case was whether the criteria for recognition of Minamata victims are appropriate.
The plaintiff, a native of Minamata, Kumamoto Prefecture, who now lives in Osaka Prefecture, asked the prefectural government in 1978 to recognize her as a Minamata disease vicitm. The prefecture refused, citing the criteria the central government set the previous year.
She joined a group of plaintiffs who sought damages in connection with the disease caused by mercury-laced waste water that chemical maker Chisso Corp. released into Minamata Bay.