The Pulp Mills case arose from an allegation by Argentina that Uruguay had violated its obligations under the 1975 Statute of the River Uruguay and other rules of international law by the fact that Uruguay had unilaterally authorised the construction of two pulp mills on the River Uruguay, which forms the boundary between the two countries. Argentina claimed that Uruguay had violated both the procedural and substantive obligations of the Statute. First Argentina argued that Uruguay had failed to follow the correct procedures laid down in the Statute before authorizing the construction of two pulp mills and a port on the river. Second, Argentina alleged that the mills would cause various types of pollution to the river ecosystem and to the environment more generally. The judgment of the Court was delivered on Tuesday 20 April. Argentina were successful in their arguments on the procedural aspects of the dispute but the Court found that there was not sufficient evidence to support their allegations of substantive environmental harm caused by the construction or operation of the pulp mills. The following post contains a brief summary of the judgment.