Both Union Carbide and the Indian government had the ethical obligation of non-maleficence; their obligation was to avoid harm to employees of the plant as well as citizens living in Bhopal. Additionally, Union Carbide and the Indian government had the ethical obligation to ensure that safety precautions were taken in daily operations of the plant as well as making corrections to known safety deficiencies.
The Indian employees had the ethical obligation of fixing the problems that were pointed out or shutting the plant down until the American owners fixed it. The Indian employees reported that the problems had been fixed or were currently being fixed, which was not true. This is an example of the ethics principle of autonomy; telling the truth, disclosure, voluntariness of action. However, the Indian employees lied in order to continue production.
Their ethical obligation should have been to be honest in their report. American employees of Union Carbide had various ethical obligations. They failed to ensure the Bhopal plant was held at the same standards of the American plants. After the first inspection, the Americans should have put some eyes and ears into the plant to make sure things were running properly. Waiting a year to do another inspection when so many things were wrong was way too long.
They were obligated to supervise the situation more than they did to make sure things were being run properly. The ethical principle the American employees should have used would be non-maleficence; avoiding harms, avoiding unjustified paternalism. American employees also had the ethical obligation of weighing the benefits and burdens to prevent dangerous conditions for employees. Union Carbide-USA (UC-USA) and Union Carbide-India (UC-India) should both be held responsible for what happened before the disaster.
UC-USA had a responsibility to ensure that UC-India corrected the safety deficiencies that it found during the inspection process. UC-India had a responsibility to correct the deficiencies that were pointed out. It is possible that the Indian government has a stake in this too. Without knowing the reasons for the exception to the law it would be difficult to say for certain whether the government had any extra responsibility in making sure that a foreign, majority-held company operated like all of the other companies in the country.