On December 1, 2022, the International Court of Justice issued its decision in the Dispute over the Status and Use of the Waters of the Silala (Chile v. Bolivia) concerning a dispute over the Silala River, which is shared by both states, and whether it is governed by international law. The case originated in 2016 when Bolivia demanded compensation for Chile’s use of the river, arguing that Chile has no rights to the river because its only means of flowing into Chile is by artificial channels. Chile instituted ICJ proceedings that year. According to a summary from the ICJ, Chile first argued that the Silala River system is an international watercourse governed by customary international law (as neither Chile nor Bolivia are party to the 1997 Convention on the Law of the Non-Navigational Uses of International Watercourses). Though Bolivia did not disagree with this argument, Bolivia countered that Article 2 of the Convention (which includes definitions of terms such as “international watercourse”) does not form part of customary international law. It also argued that the river’s “unique characteristics” must be taken into account when applying customary rules on international watercourses to the river. Moreover, in addition to asking the Court to reject Chile’s arguments, it also asked the Court “to find that the surface flow of the Silala has been ‘artificially enhanced’.” The Court rejected Bolivia’s arguments, holding that it is not necessary for Bolivia to have recognized that the definition of “international watercourses” in Article 2 are part of customary international law, and that Bolivia’s insistence on the river’s unique characteristics “does not change the fact that it has expressed its unequivocal agreement with the proposition that the customary international law on non-navigational uses of international watercourses applies to all of the Silala waters” (¶ 58). Since the parties agree, the Court did not have to make an official decision on the matter.

When the proceedings were instituted, Chile’s claim that its equitable and reasonable use of the Silala (including the artificially enhanced parts) was opposed by Bolivia. As the proceedings progressed, the Court notes that “it became apparent that the Parties agree” and that, moreover, “[t]he Parties also agree that they are both entitled to the equitable and reasonable utilization of the Silala waters under customary law.” Noting that it was not for the Court to address “a possible difference of opinion regarding a future use of these waters,” the Court moved on to Chile’s third argument.

Chile had also initially claimed to be entitled to its current use of the river, and Bolivia opposed this argument regarding the parts that were artificially enhanced. Again, the Court referenced statements made in the early part of the proceedings and concluded that the parties now agreed on this issue. However, the Court noted that it was unsure whether Chile had also wanted the Court to declare that it has the same rights to the water in the future. In any case, the Court reiterated that both parties agree that the other has a right to equitable and reasonable utilization of the Silala waters.

While the parties agree that the customary obligation to prevent transboundary harm applies to the whole of the Silala waters, they disagree regarding the threshold of this obligation. Bolivia argues that the obligation applies only to the causing of “significant” harm, whereas some of Chile’s statements suggest that it believes the threshold is lower. However, the Court concluded that without “more specific indications to the contrary” the Court cannot conclude that there is a disagreement, and for that reason it did not issue a decision on this issue either.

Chile’s fifth submission concerned Bolivia’s obligation to notify and consult with Chile before taking any action that might have an adverse effect on the Silala River. Specifically, the parties disagreed regarding the scope of and threshold for the application of the obligation, as well as whether Bolivia has complied with the obligation concerning certain activities. Regarding the threshold, Chile and Bolivia disagree about the meaning of Article 11 of the Convention and whether it reflects customary international law. That article reads: “Watercourse States shall exchange information and consult each other and, if necessary, negotiate on the possible effects of planned measures on the condition of an international watercourse.” The Court referred to commentaries to the International Law Commission Draft Articles, noting that the commentary to Article 11 does not refer to any relevant state practice. That, in conjunction with the lack of general practice or opinion juris, led the Court to determine that it was unable to conclude that Article 11 formed part of customary international law and therefore, it could not accept Chile’s argument that Article 11 reflected a general obligation under customary international law to exchange information regarding any planned measures. In addition, though the parties agree that Article 12 reflects customary international law, they disagree regarding its interpretation. Article 12 concerns a notification requirement prior to permitting or implementing measures that might have a significant adverse effect on the watercourse at issue. Referring to its own jurisprudence, the Court concluded that Article 12 does not reflect a rule of customary international law “that is more rigorous than the general obligation to notify and consult contained in its own jurisdiction.” Therefore, the Court held that “each riparian State is required, under customary international law, to notify and consult the other riparian State with regard to any planned activity that poses a risk of significant harm to that State.”

Following that, the Court was asked to indicate whether Bolivia had complied with that standard, and it concluded that Chile “had not demonstrated or even alleged any risk of harm, let alone significant harm, linked to the measures planned or carried out by Bolivia.” Therefore, the Court found that Bolivia had not breached its obligation to notify and consult. Moreover, the Court reminded the parties “to bear in mind the need to conduct consultations on an ongoing basis in a spirit of co-operation.”

The Court then considered Bolivia’s three counterclaims. First, Bolivia asked the Court to decide and declare that it has sovereignty over the artificial parts of the Silala that are located in its territory, and that consequently, it has the right to determine how to manage them. However, because the Parties have since agreed on this point, the Court did not have to adjudicate it. Second, Bolivia asked the Court to determine that it has sovereignty over the artificial flow of the Silala waters engineered or produced in its territory and that Chile has no acquired right to that artificial flow. Here, the Court indicated that Chile has clearly stated that it is not claiming an acquired right and that it recognizes Bolivia’s rights over the infrastructure. So again, it did not need to adjudicate on this issue. Finally, Bolivia asked the Court to determine that any requests by Chile to Bolivia “for the delivery of the enhanced flow of the Silala, and the conditions and modalities thereof, including the compensation to be paid for any such delivery, are subject to the conclusion of an agreement with Boliva.” Here, the Court declined to adjudicate, as it concerns a “future, hypothetical situation.”

Judge Tomka published a declaration stating that while the Court is permitted to interpret the final submissions of a party, it “should avoid an interpretation that is at odds with the ordinary meaning of the words and legal concepts used in the final submissions.”

Judge Charlesworth also filed a declaration. Though she agreed with the Court’s rejection of Chile’s claim regarding Bolivia’s breaching of its obligation to notify and consult, as well as Bolivia’s argument about future agreements, she fundamentally disagrees with the Court’s decision on several occasions not to resolve the issue in dispute, but rather gives “attention to the question—at issue between the Parties—as to whether that dispute persists.” Judge Charlesworth argues that this approach (which she calls the Court’s “diversion to this ‘meta-dispute’”) “introduces new uncertainties into the concept of a dispute,” has no basis in the Court’s jurisprudence, and does not fit the facts at issue very well. Finally, she argues “that the Court’s reasoning underestimates the contribution a declaratory judgment may make in this case.”

Judge ad hoc Simma filed a separate opinion that is similar to Judge Charlesworth’s declaration. He writes that “[i]t is a curiosity of this Judgment that it decides almost nothing.” In particular, he felt that “[t]he Judgment’s test to decide whether a dispute has disappeared in the proceedings” is “too low a bar”—referring to the Court’s assertion that it must “‘ascertain whether specific claims have become without object as a consequence of a convergence of positions or agreement between the Parties, or for some other reason’ (emphasis added).” Judge ad hoc Simma is “not aware of any case where the Court has used the ‘convergence of positions’ standard,” nothing that such a situation is “not an agreement.”