A La Rioja Judge Suspended a Mining Project in San Juan: The Vicuña Case and the Questions It Raises on Predictability of the Mining Investment Regime
On April 14, 2026, Judge María Greta Decker of the Chilecito Court in the Province of La Rioja granted a self-executing measure (medida autosatisfactiva) brought by the Provincial State of La Rioja against Vicuña Argentina S.A. and ordered the thirty-day suspension of the activities of the Vicuña Mining Project, a large-scale undertaking comprising the José María and Filo del Sol deposits. The project is located in the territory of the Province of San Juan, approximately one and a half kilometers from the border with La Rioja. The ruling also prohibited the circulation of the company's machinery and vehicles through the Guandacol – Santa Elena – Zapallar – Las Cuevas – La Ciénaga road corridor, which crosses the La Rioja departments of General Lamadrid and Coronel Felipe Varela.
The decision was issued without prior hearing of the defendant (inaudita parte), as is typical of self-executing measures, and its effectiveness is conditioned upon Vicuña Argentina S.A. submitting to the environmental authorities of La Rioja the comprehensive Environmental Impact Assessment (EIA) of the mining project and its access road corridor. Once the EIA is submitted, the measures are lifted.
The Facts of the Case
The conflict has roots dating back to 2021, when La Rioja's environmental authority was notified of a public participation instance called by San Juan's Ministry of Mining and Environment regarding the José María project. On that occasion, La Rioja opposed the EIA submitted by the company before San Juan, pointing out that the Laguna Brava Reserve and the project's access road constituted zones of direct influence that should have been considered in the environmental assessment. According to the judicial ruling, the company (then called DE.PRO.MIN S.A.) had signed an agreement in August 2023 with La Rioja for the construction and maintenance of the provincial access road, but completely failed to fulfill its obligations.
Tensions escalated when the company initiated the EIA update before San Juan's Ministry of Mining while simultaneously processing in La Rioja's jurisdiction the environmental assessment update for the road corridor. La Rioja warned that the practical effect was the segmentation of the environmental assessment of a single mining establishment between two provincial jurisdictions, and required the company to also submit the complete project EIA before its authorities. Vicuña Argentina S.A. refused, invoking the provincial autonomy of San Juan, that province's exclusive jurisdiction over the deposit, and the absence of technical evidence of environmental damage in La Rioja territory.
The Procedural Path Chosen
The Province of La Rioja resorted to the self-executing measure, a procedural instrument that doctrine defines as an urgent, autonomous, and definitive jurisdictional solution, which is exhausted with its own favorable ruling without the need for a subsequent knowledge proceeding. Unlike a precautionary measure, the self-executing measure does not require proof of mere plausibility of the right but rather strong probability, and its issuance produces the definitive satisfaction of the claim. Also unlike the precautionary measure, it does not require counter-security.
The combination of this remedy with the precautionary principle in environmental matters is not entirely unprecedented in Argentine case law — in “Comunidad del Pueblo Diaguita de Andalgalá c/ Catamarca” (Supreme Court, 2012), this path was attempted to halt mining activities, although unsuccessfully — but what is distinctive about the Vicuña case is that the measure was effectively granted, and that its promoter is a province acting against a company established in another jurisdiction.
Judge Decker considered that the admissibility requirements were met. She grounded the urgency in the nature of mining activity, in the advanced stage of the project (already in the exploitation phase), and in the risk of irreparable environmental damage on La Rioja soil. She invoked the precautionary principle of Article 4 of the General Environmental Law (Law 25,675), according to which the absence of information or scientific certainty cannot be used as a reason to postpone the adoption of effective environmental protection measures.
The Questions the Decision Raises
The ruling raises questions that go beyond the specific case and directly touch the architecture of the mining investment regime in Argentina.
The first is jurisdictional. The Vicuña Project is located in San Juan territory. The mining concession was granted by San Juan authorities. The EIA was submitted to and evaluated by San Juan's environmental body. The La Rioja judge based her jurisdiction on the fact that part of the project's activities (vehicle transit, circulation of substances, use of the road corridor) take place on La Rioja soil, and on the fact that the water resources of the area are shared between both provinces. The logic of the argument is that the environment is an indivisible collective good and that the effects of an undertaking do not stop at the provincial border. But the practical consequence is that a court outside the jurisdiction where the project is located can order the suspension of its activities, without hearing the company, based on the precautionary principle.
The second question concerns the evidentiary standard. The measure was issued without the judge having independent technical expert opinions or the defendant's position. The ruling itself recognizes that the application of the precautionary principle does not require proof of actual damage: the danger of serious or irreversible damage is sufficient. It is a normatively correct criterion (as established by Article 4 of Law 25,675), but its concrete application to an undertaking that had already been environmentally assessed by the authority of the province where it is located creates tension with the legal certainty of the investment. The investor who obtained EIA approval in San Juan now faces suspension of operations by order of a La Rioja court, based on risks that were not demonstrated but presumed under the precautionary principle.
The third point is the procedural instrument itself. The self-executing measure was issued inaudita parte. Vicuña Argentina S.A. had no opportunity to be heard before the suspension of its activities was ordered. The judge acknowledges that the right of defense must be guaranteed, but the very nature of the self-executing measure presupposes that the ruling is issued without prior adversarial proceedings. For a large-scale mining project, a thirty-day suspension of operations has significant economic implications: continuing fixed costs, contractual commitments with suppliers, labor obligations, and, not least, the reputational effect before international investors and financiers.
The Impact on Predictability of the Mining Regime
Argentina has historically promoted mining investment on the basis of a legal framework that grants provinces original ownership of natural resources (Article 124 of the National Constitution) and that organizes the activity through the Mining Code and fiscal stability regimes. The system's logic is that the investor who obtains the mining concession and environmental approval from the granting province has a stable frame of reference to plan an investment that is typically measured in decades.
The Vicuña case introduces a variable that this framework does not explicitly contemplate: the possibility that a neighboring province, which is not the grantor, orders the suspension of the project through a summary judicial action based on the precautionary principle, without the need to demonstrate damage or to hear the company before deciding. If the criterion were to consolidate, any mining undertaking located near an interprovincial border would be exposed to multiple jurisdictional interventions, each with its own environmental assessment requirements, its own timing, and its own assessment of risk. The result would be an overlap of competencies that would hinder long-term investment planning.
This does not mean that La Rioja's environmental concern lacks foundation. Shared water resources, the connectivity of surface and underground watersheds, and the proximity of sensitive ecosystems such as the Laguna Brava Reserve are factors that should reasonably be part of any serious environmental assessment. The problem is not the legitimacy of the claim but the mechanism: the self-executing judicial path, resolved without bilateral process and with immediate effects on operations, imposes disproportionate costs when alternative institutional channels exist (interprovincial coordination, federal intervention in environmental matters, the Supreme Court's original jurisdiction over conflicts between provinces) that would allow the issue to be addressed without paralyzing productive activity while it is being resolved.
Final Considerations
Judge Decker's ruling is a landmark case. It highlights the tensions between preventive environmental protection and the predictability required by long-term mining investment. It also exposes the limitations of a system where the environmental impact assessment of a binational or biprovincial-scale project remains fragmented between jurisdictions that do not necessarily coordinate with each other.
For industry operators, the case reinforces the importance of considering transjurisdictional impacts from the project design stage and of maintaining open channels with authorities of neighboring provinces, even when they are not the granting jurisdiction. The history of the Vicuña Project shows that the lack of institutional dialogue can escalate to a judicial suspension of operations. For regulators and legislators, the case underscores the need for interprovincial coordination mechanisms in environmental assessment of projects with transboundary impact, an area where the General Environmental Law establishes principles but not sufficient operational instruments.
This note is for informational purposes only and does not constitute legal advice. For a specific analysis, please contact our team at contact@jfcattorneys.com.