In this case, the plaintiffs were the resident marine mammals which inhabit the waters in and around the Tañon Strait and were represented by their Stewards and an NGO established for the welfare of the fisher folk. The plaintiffs were challenging the decision authorizing the oil exploration activities in the Tañon Strait.
The plaintiff challenged the decision on the basis that it had an important impact on the environment as the seismic activities had reduced the amount of fish which can be found in the strait. They also alleged that not consultation or discussion with the local stakeholders had taken place prior to the issuance of the Environmental Compliance Certificate.
The Supreme Court held that in accordance to the environmental law, every Filipino is entitle to act as a steward of nature and that consequently, the plaintiff had the standing to sue. The court also considered that according to Proclamation No. 2146, the Tañon Strait is an environmentally critical area and has been declared a protected area in 1998. Consequently, no activity outside the scope of its management plan could take place without the delivery of an Environmental Compliance Certificate granted after a undergoing an Environmental Impact Assessment to determine the effect of such activity on the ecosystem. In that case, the oil company already started to conduct oil exploration activities without an Environmental Impact Assessment and before being granted and Environmental Compliance Certificate, in violation of the National Integrated Protected Areas System Act of 1992. Furthermore, the court held that the Presidential Decree No. 87 which was used as a legal basis for the service contract between the Government and the oil company in charge of the oil exploration activities was ultra vires. Indeed, because the Tañon Straits is a protected area, the contract would have required to be allowed by a law passed by the Congress. Therefore, the constitutional court cancelled the contract and all the permits related to the oil exploration in the Tañon Straits.