All appeals are dismissed.

The costs of appeal are assessed against the plaintiffs.

The grounds of appeal are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed).

1. In general, the claimant shall bear the burden of proving the causal relationship between the harmful act and the loss in a claim for damages.

However, in a lawsuit claiming compensation for damages due to air pollution or water pollution, there is a large amount of cause material discharged by a company as a medium of atmosphere or water, and there is a field in which current scientific level cannot be clarified with respect to pollution issues, so it is very difficult or impossible to prove one high interest which constitutes a causal relationship between the harmful act and the damage.

Therefore, it would be a result of the actual refusal of judicial relief due to pollution to the victim of a scientificly strict proof of the existence of a factual causal relationship in such pollution lawsuit. However, the victim company may not be exempted from liability unless it proves that the perpetrator discharges any harmful material, and if the damage was caused by reaching the damaged object, it would be difficult for the victim company to investigate the cause much more easily than the victim in technical and economic aspects, and there is a concern for covering the cause.

(See Supreme Court Decision 2009Da84608, 84608, 84615, 84622, and 84639 Decided January 12, 2012, etc.). However, even in such cases, the perpetrator discharges any harmful cause substance, at least the fact that the degree of harm exceeds the ordinary participation limit in social life, the fact that it reached the damaged object, and the burden of proof as to the fact that the victim suffered damage remains the victim.