A US federal court has ruled that neither Union Carbide Corporation (UCC) nor its former chairman Warren Anderson were liable for any environmental remediation or pollution-related claims made by the victims of the 1984 Bhopal gas tragedy.

In one of the world's worst disasters at the Bhopal plant, formerly owned and operated by Union Carbide India Limited, an entity once owned by UCC, leaked poisonous gases killed an estimated 22,000 people in the December 1984 accident.

In his ruling Wednesday, US district Court Judge John F. Keenan concluded that -- even when viewing the evidence in the most favourable light for the plaintiffs -- UCC is not directly liable, nor liable as an agent of Union Carbide India Limited (UCIL), nor liable under a veil-piercing analysis.

The court concluded that "It is beyond dispute that Union Carbide India Limited" -- and not UCC -- "generated and disposed of the waste which allegedly polluted plaintiffs' drinking water".

Additionally, the court found that UCC did not direct remediation efforts that occurred after the Bhopal plant was closed by the Indian government.

Citing a 1998 court verdict in a case involving KFC, the court said that legally the mere assertion that a corporate parent is or was involved in the decision-making process of its subsidiary, or that it controlled the legitimate policies of its subsidiary, will not shift liabilities among distinct corporate entities.

Plaintiffs Janki Bai Sahu and others had alleged that "toxic substances seeped into a ground aquifer, polluting the soil and drinking water supply in residential communities surrounding the former Bhopal plant site".

They alleged that exposure to soil and drinking water polluted by hazardous waste produced Union Carbine India Ltd caused injuries.

In a press release, UCC said the court's decision not only dismisses plaintiffs' claims against UCC, but also clarifies that UCC has no liability related to the plant site.

It also acknowledges the matter of site ownership and liability as being the responsibility of the Madhya Pradesh state government, it said.