At the instigation of non-governmental organizations (NGOs), the chief judicial magistrate of Bhopal, India, has issued a third criminal summons to Dow Chemical over the deadly 1984 gas leak at its now-wholly owned subsidiary Union Carbide (UCC).

The well-publicized accident killed 22,000 people and exposed more than 570,000 to high levels of toxic gas.

Dow has been called to appear in Indian court on Nov. 12, 2014, to explain why UCC has not appeared before the court. 

Under a treaty between India and the US, the latest summons will be communicated by the Indian government to the US government for service on Dow at its Midland, Michigan headquarters.

Indian law requires the US chemical giant to respond to the summons once properly served. Reports said the second summons, issued in February 2014, was not properly served. 

Since it acquired UCC in 2001, Dow has maintained that the two companies are entirely separate and that it bears no responsibility for Bhopal.

According to Amnesty International, Dow's management has also used US securities rules to block a shareholder resolution of May 2014 asking for a report on the financial, reputational and operational impact of the catastrophe on Dow's business. 

Amnesty noted that before its acquisition by Dow UCC "repeatedly ignored orders to appear before the Indian courts to answer criminal charges concerning the disaster. Refusing to comply with the summons would be to treat the Indian justice system with contempt, undermining Dow's credibility as an investor in India," the organization said.

Along with the criminal case, UCC and Dow are embroiled in two civil suits in India relating to the gas leak and contamination at Bhopal. A related US civil suit was recently dismissed, but is being appealed.