This article analyses the growing resistance to judgments of the International Court of Justice arising out of domestic law in Latin America, through a study of challenges to the authority of the Court’s judgments regarding territorial and maritime delimitation in the region. These challenges are based upon the ‘territory clauses’ found in many Latin American constitutions, which were used to set national boundaries following colonial independence. Territory clauses that once developed international law doctrines such as uti possidetis iuris are now being used against prevailing international law rules, in a process described in this article as ‘constitutional resistance’.

This article explains the nature of ‘territory clauses’ in Latin America, i.e., clauses that constitutionally define the national territory in reference to international law. It then describes the process of ‘constitutional resistance’, by which local authorities have used these clauses to oppose ICJ judgments, leading to various results, such as non-appearance in further proceedings, constitutionalizing exclusively favourable judgments, deferring the implementation of a judgment to the Constitutional Court or implementing only certain ICJ judgments, while creating legal barriers to the implementation of judgments that, in the State’s view, negatively affect their territory.

These challenges based on territory clauses are studied through prominent ICJ cases involving Nicaragua, Honduras, El Salvador, and Colombia. The article also explores how the lack of a strong territory clause eased the implementation of the Peru v. Chile judgment, and how the recent non-appearance of Venezuela in its current ICJ proceedings with Guyana, is partly based on constitutional justifications.