San Juan River 인근에서의 특정 활동과 공사에 관한 사건(코스타리카/니카라과, 2015)

In Pulp Mills on the River Uruguay (Argentina v. Uruguay) of 2010, ICJ articulated the procedural and substantive obligations under international environmental law. Five years thereafter, ICJ has another opportunity to consider and enlarge those obligations in similar context, i.e., in the context of an international river San Juan between Costa Rica and Nicaragua. The two States instituted proceedings against each other, and ICJ joined the proceedings of two cases and delivered its decision in 2015. In Costa Rica v. Nicaragua, the Court found that Costa Rica had sovereignty over the disputed territory and that Nicaragua had violated Costa Rica's territorial sovereignty by engaging in certain activities therein. However, the Court concluded that Nicaragua had not breached any procedural obligations owed to Costa Rica under treaties or the customary international law of the environment. Nor had Nicaragua, according to the Court, breached any substantive obligations concerning transboundary environmental harm. In Nicaragua v. Costa Rica, the Court found that Costa Rica had violated its procedural obligations under general international law by failing to carry out an environmental impact assessment (EIA) concerning the construction of a road along the San Juan River. However, the Court concluded that Costa Rica had not breached its substantive obligations under customary international law concerning transboundary harm. What is notable in the 2015 decision is that, in elaborating the procedural obligations under customary international law that requires States to exercise due diligence in preventing significant transboundary harm, the Court established a sequence of three obligations. That is, a State of origin must ascertain if there is a risk of significant transboundary harm, which would trigger the obligation to carry out an EIA. If the EIA confirms that there is a risk of significant transboundary harm, the State is required to notify and consult with potentially affected States. This approach of the Court could suggest wrongly that, only when the State of origin's EIA confirms that there is a risk of significant transboundary harm, that State must notify the potentially affected States. However, notification of a potentially affected State prior to the EIA may well be necessary, as evidenced by the Espoo Convention on EIA. On the other, the precautionary principle calls for lower threshold for triggering the obligation to carry out an EIA. Thus, the EIA process should be triggered even earlier than the ascertainment of the risk.