This article introduces and evaluates the judgment of the International Court of Justice (ICJ) regarding the case concerning certain activities carried out by Nicaragua in the Border Area (Costa Rica v. Nicaragua) proceedings joined with construction of a road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica) from an environmental point of view. The case was one of the latest environmental related affairs before the ICJ and the Hungarian literature had been looking forward with great expectation regarding the Court’s award. The conclusion of this essay is that in spite of the nature of the dispute, the symmetry of the conflict and the constant need for the improvement of the general international environmental law, the ICJ missed the opportunity to develop international environmental customary law and the case will stay in the shadow of the ICJ’s previous judgement on Pulp Mills on the River Uruguay.