La Oroya and Inter-American Innovations on the Right to a Healthy Environment

For the first time in its 50-year history, the Inter-American Court of Human Rights (the Court) established standards for the right to a healthy environment in a contentious case that did not involve Indigenous peoples. In La Oroya v. Peru, the Court declared Peru responsible for violating several rights, including the right to a healthy environment, due to the environmental degradation and health crises in La Oroya—one of the world’s most polluted cities.

Several innovations arise from this judgment, which have been discussed here, here, and here. Specifically, regarding the right to a healthy environment, the Court addresses for the first time pollution in air, water, and soil—marking a departure from previous cases that primarily focused on communal property rights and deforestation—and even goes as far as to refer to the right to a healthy environment as jus cogens. Additional innovations include the establishment of standards for State and corporate due diligence, as well as collective reparations.

This post argues that such innovations would have not been possible without the ever-expanding horizon of Inter-American case law and approaches, which have distinctively flourished through dialogue with supranational and domestic courts, as well as a vibrant ecosystem of communities of practice in human rights in the region. After briefly introducing (1) the case background, the innovations will be explored in the decision’s (2) preliminary objections and merits and reparations, situating them within the Inter-American practice, and concluding with a reflection on (3) the outstanding challenges.

A Century of Pollution Reaches the Court: Case Background, Facts, and Procedure

Located in Peru’s Central Highlands, the La Oroya district has faced a century of environmental degradation and health crises due to the operations of the La Oroya Metallurgical Complex (CMLO). Established in 1922 by the US-owned Cerro de Pasco Copper Corporation, the complex has changed hands multiple times—nationalized in 1974 and privatized in 1997 to the US-based Doe Run. Yet, it has consistently emitted a harmful mix of heavy metals and other pollutants, severely impacting the health of its over 33,000 residents (para. 67). In 2006, these emissions earned La Oroya the reputation of being one of the world’s most polluted cities.

The path to the Inter-American Court began in December 2006, when the Inter-American Association for Environmental Defense (AIDA), Earth Justice, and the Asociación Pro Derechos Humanos (the representatives) lodged a petition with the Inter-American Commission on Human Rights (the Commission) on behalf of residents of La Oroya. This move came after exhausting domestic remedies, prompted by the Peruvian government’s failure to comply with the May 2006 ruling of Peru’s Constitutional Tribunal—which had ordered remedial measures to address violations related to the rights to health and the environment of the inhabitants of La Oroya.

In November 2020, the Commission issued its Merits Report No. 330/20, in which it concluded that Peru was responsible for violations of several rights and recommended that the State implement a series of reparatory measures for the residents of La Oroya. As Peru failed to report on the implementation of these measures, the Commission decided to refer the case to the Court in September 2021.

In its pleadings, the Commission argued that Peru’s failure to establish a clear regulatory framework, enforce oversight, and impose sanctions enabled the CMLO to produce high levels of pollution. This, the Commission contended, violated several articles of the American Convention on Human Rights (the Convention): 4.1 (right to life), 5.1 (right to personal integrity), 13.1 (right to access information), 19 (rights of the child), 23.1.a (right to participate in government), and 26 (progressive realization of economic, social, and cultural rights), to the detriment of 80 victims, including 23 children at the time of the initial petition. The representatives also emphasized that the rights to life and personal integrity of women, pregnant women, and the elderly were particularly compromised.

Peru denied any international responsibility, asserting that following a 2006 ruling by the country’s Constitutional Tribunal, it had taken measures to reduce environmental pollution and enhance the participation of interested parties in environmental decision-making. Additionally, Peru contested any causal link between the environmental conditions in La Oroya and the resultant fatalities and detrimental health conditions.

The Court delivered its judgment within two years, a period during which it held a public hearing outside its San José headquarters, in October 2022, in Montevideo, Uruguay. It received 17 amici curiae briefs from civil society groups and academic institutions—more than in previous environmental-related contentious cases, such as Sarayaku v. Ecuador (2012) and Lhaka Honhat v. Argentina (2020), which received 9 and 8 briefs respectively.

Inter-American Innovations on the Right to a Healthy Environment

Preliminary Objections: Direct Enforceability under the American Convention and Collective Scope

Among the preliminary objections raised by the respondent State, Peru argued that the direct enforceability of the rights to health and a healthy environment under Article 26 of the Convention was not legally supported. The Court rejected this objection, reaffirming its consistent practice of interpreting the Convention in a systematic and evolutionary manner (para. 25) in light of other relevant treaties and norms (para. 26). It cited its ruling in Lhaka Honhat v. Argentina and its Advisory Opinion OC-23/17 on the Environment and Human Rights, as these decisions mark a turning point in the Court’s jurisprudential development by recognizing the right to a healthy environment as an autonomous right under Article 26. Previously, the Court had only acknowledged this right indirectly, mainly in relation to collective property rights of Indigenous peoples (Article 21).

Furthermore, Peru urged the dismissal of the representative’s claims regarding collective damages beyond individuals listed in the Commission’s Merits Report. The Court also rejected this consideration. Referencing OC-23/17 (para. 59), the Court highlighted that since the right to a healthy environment embodies both collective and individual connotations, violations of this right likely extend beyond the individuals explicitly indicated by the Commission, impacting the broader community in La Oroya.

Merits and Reparations: Pollution, Due Diligence, and Collective Reparations

A groundbreaking aspect of this ruling is its focus on a previously underemphasized issue: pollution (whereas previous case law primarily addressed natural resource extraction in communal lands of Indigenous peoples). In establishing the State’s responsibility for violating the right to a healthy environment, the Court’s analysis focused on two main controversies revolving around this issue: firstly, whether the pollution from CMLO constituted a significant risk for the environment; and secondly, whether Peru fulfilled its obligations—both substantive and procedural—related to the right to a healthy environment (para. 154), including evaluating Peru’s efforts towards the progressive realization of this right, aimed at preventing such pollution.

The Court found that CMLO’s activities led to dangerously high pollution levels in the air, water, and soil—compartments the Court deemed integral to the environment, finding support in decisions from the Supreme Court of Mexico and the Constitutional Court of Colombia (para. 118). Drawing on scientific data from government and civil society organizations—the National Office for the Evaluation of Natural Resources (1986) and CooperAcción (2000)—it was evident that Peru had been aware of the risks to such environmental compartments since 1981, the year it recognized the Court’s contentious jurisdiction.

A second innovative element of the decision arose in the Court’s examination of Peru’s fulfillment of substantive obligations, particularly in the application of the due diligence standard, which it interpreted in light of the UN Guiding Principles on Business and Human Rights (UNGP) (para. 111). Previous cases had provided content to this standard toward private entities, but never with such depth in environmental matters. As CMLO shifted from state management (1981-1997) to private ownership, which continues to the present, the Court emphasized that obligations under Article 1.1 of the Convention—to respect and guarantee rights—require States to prevent activities within their jurisdiction from causing significant environmental damage, applying this requirement to both public and private entities. In interpreting this in light of the prevention principle, the Court concluded that, to fulfill this due diligence standard, Peru should have adequately regulated, overseen, and monitored the CMLO operations (para. 157).

The Court found that the absence of specific environmental protection legislation related to mining-metallurgical activities until 1993 constituted a breach of the duty to regulate. Furthermore, although it was established that the State eventually took steps to supervise and monitor CMLO’s activities to reduce environmental damage, the Court highlighted that more effective measures were only implemented after 2010—decades after the recognition of severe pollution in La Oroya. Legislative reports confirmed that efforts prior to 2010 were insufficient and inadequate, allowing the continued release of pollutants despite known detrimental impacts on air, water, and soil.

In its analysis of procedural duties under the right to a healthy environment, the Court emphasized the importance of access to information and political participation. It noted that the Escazú Agreement, which strengthens these aspects, has not been ratified by Peru. The Court anchored its analysis in Articles 13 and 23 of the American Convention—freedom of expression and political rights—rather than directly linking these rights to a right to a healthy environment. It highlighted that prior to 2003, the State failed to inform the citizens of La Oroya about severe health risks related to pollution, and that subsequent actions overlooked the specific hazards posed by emissions from the CMLO (para. 253). While some initiatives were introduced to involve the community in environmental decision-making, the Court found no evidence that these measures gave the victims a meaningful voice or influence over policy (para. 260).

Regarding the progressive realization of the right to a healthy environment, the Court noted that Peru’s decision in 2017 to relax air quality standards—from 20 μg/m³ to 250 μg/m³ of sulfur dioxide over a 24-hour period—was made without adequate justification and disregarded the precautionary principle. By acquiescing to this ‘regulatory chill’—symptomatic of an extractivist international investment system, as noted by David Boyd—the Court determined that Peru failed to fulfill its duty of progressively developing the right to a healthy environment (para. 187).

A third legal milestone introduced by this ruling is the collective scope of certain reparations. Building upon the already distinctive character of the Court’s integral reparations—which entail guarantees of restitution, rehabilitation, satisfaction, non-repetition, and compensation—the inclusion of nine measures within the guarantees of non-repetition is a novel addition. These initiatives are aimed not only specifically at the victims but also broadly at the residents of La Oroya. They involve actions with structural effects as they imply regulatory improvements in air quality standards and monitoring infrastructure, as well as enhancements in the capacities and infrastructure for monitoring air, soil, and water quality. They include the training of judicial and administrative officials to facilitate the application of the due diligence standard and implement environmental restoration and compensation plans, thereby benefiting La Oroya as a whole. Furthermore, the ruling involves private operators by calling on the State to ensure their compliance with the UNGP.

Lastly, but certainly not least, the Court’s reference to environmental protection as a jus cogens norm is revolutionary, as no other international court or treaty body has made such a suggestion. This would elevate the prohibition of illicit or arbitrary actions causing severe, lasting, and irreversible environmental damage to a non-derogable, universal principle, akin to the prohibitions of genocide, slavery, and crimes against humanity. Justices Ricardo Pérez Manrique, Eduardo Ferrer Mac-Gregor, and Rodrigo Mudrovitsch, in their concurring opinion, further delve into this reference, arguing that the elements of customary international law—usus (material element) and opinio juris (psychological element)—are evident for the right to a healthy environment. They consider that the former element is demonstrated by numerous international instruments, such as the 1972 Stockholm Conference and the 1992 Rio Conference, as well as the domestic constitutions of several States recognizing such a right. The UN Resolution 76/300 of 2022 on the human right to a clean, healthy, and sustainable environment, adopted by the majority of members of the international community, the justices consider, reflects the latter element.

New Horizons, Unsettled Legal Challenges

As this post maps, the justice this ruling delivers to the victims and residents of La Oroya, as well as its potential for broader environmental and climate protection in the Americas (see the post by Verena Kahl and José Rodríguez-Orúe), could not have been realized without two defining characteristics of the Inter-American system: the evolving trajectory of the Court’s jurisprudence over the past 50 years, and its practice of open dialogue with the region’s domestic courts and civil society organizations. Yet, its place in the annals of history remains a topic of debate.

Within the Court, formalistic arguments continue to challenge the interpretation of the right to a healthy environment as an independent right directly enforceable under Article 26 of the Convention, as evidenced by the two partial dissenting opinions from Justices Humberto A. Sierra Porto y Patricia Pérez Goldberg. Moreover, it remains unresolved whether this ruling will lead to the technically and financially burdensome clean-ups of damages caused by past conducts being shouldered not only by an already strained State or small economic actors but by the affluent transnational corporation whose misconduct remains largely unpunished. This issue persists despite the Court mandating that the State require mining titleholders to compensate for environmental damages in adherence to the “polluter pays” principle. The case of Doe Run Peru starkly illustrates this conundrum: After declaring bankruptcy in 2009, the company transferred its assets to its workers in La Oroya as labor creditors. This maneuver leaves substantial foreign-owned wealth—potentially useful for funding costly remedial actions—out of the Court’s and the State’s reach, and the costs of environmental remediation to the new, financially compromised worker-creditors.

Compliance with and implementation of reparations will undoubtedly present formidable challenges, making the vigilance and proactive involvement of advocacy communities as crucial as ever.

As part of a collaborative alliance to enhance accessibility, a Spanish version of this article is available on Agenda Estado de Derecho.

This publication was supported by the TransLitigate project (ERC-2021-STG 101039648), funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Council. Neither the European Union nor the granting authority can be held responsible for them.