The Justiciability of the Precautionary Principle in the Tagaeri and Taromenane et al. v. Ecuador before the Inter-American Court of Human Rights

[Juan Auz is an Ecuadorian lawyer and a postdoctoral researcher at Tilburg University’s Law School]

On March 14, 2025, the Inter-American Court of Human Rights (IACtHR) made public a landmark ruling holding Ecuador internationally responsible for the violation of various rights of the Tagaeri and Taromenane, the last remaining indigenous peoples living in voluntary isolation (PIAV) in the western Ecuadorian Amazon (for an early commentary see here). This entry explores how the judgment reaffirmed the IACtHR’s expansive approach to Indigenous rights and ventured into uncharted legal territory by treating the precautionary principle as a justiciable obligation rather than a mere interpretative aid. This bold move has significant implications for the intersection of environmental law and human rights, particularly in cases involving Indigenous communities whose survival hinges on territorial integrity, limitation of extractive activities, self-determination and non-contact policies.

Context and Significance

The Tagaeri and Taromenane, Indigenous groups living in voluntary isolation in the Ecuadorian Amazon, have long been under threat from extractive industries, illegal logging, and territorial encroachment. Their survival depends on the integrity of their land and strict adherence to the principle of non-contact, which recognizes their right to remain isolated without interference. The Ecuadorian government has recognized this status by establishing the Zona Intangible Tagaeri-Taromenane (ZITT), a legally protected area meant to shield these communities from external pressures. However, despite these protections, oil exploration and extraction activities—particularly within the Yasuní National Park—have continued to encroach on their territories.

The IACtHR case arose from a series of violent incidents, including the massacre of several Tagaeri and Taromenane individuals in 2003, 2006, and 2013, events that highlighted the vulnerabilities of these Indigenous communities. The applicants argued that Ecuador had failed to implement adequate measures to prevent contact, ensure territorial integrity, and uphold its international obligations under the American Convention on Human Rights.

Apart from the bold interpretation of the precautionary principle that will be analyzed in the later section, the IACtHR addressed the complexity of consulting with people who have chosen to remain uncontacted. The Court noted that respecting their free self-determination and their choice to remain isolated means that Indigenous peoples in voluntary isolation do not engage in conventional forms of participation. Consequently, it becomes impossible to conduct free, prior and informed consultations according to the standards established by the Court regarding the determination of their territory and any development or investment projects that may impact them. In this context, the duty to consult translates, for the PIAV, into an obligation for the State to consider the decision of these groups to maintain their isolation in any project or decision that may affect them. This includes incorporating the precautionary principle and ensuring that the measures adopted are proportional, taking into account their way of life and the potential impact on it.

The IACtHR underscored the inextricable link between the Tagaeri and Taromenane’s territory and their survival as ecosystemic peoples. Their right to collective property, self-determination, and autonomy is contingent on preserving their land and strictly enforcing the principle of non-contact. Yet, Ecuador’s handling of oil exploitation in Yasuní Park revealed a glaring failure to uphold these protections.

One aspect that is decisive to the finding of a violation of the right to collective property and self-determination is the nomadic nature of the PIAV, whose territorial outreach is coterminous with their mobility patterns. The IACtHR sided with the applicants by stressing that Ecuador had to adopt a flexible approach when delimiting the ZITT so it could be adjusted according to the presence of PIAV. 

The Precautionary Principle in the Tagaeri and Taromenane’s Dicta

At the heart of the Court’s reasoning was the application of the precautionary principle. In paragraphs 225-227, the Court made an unprecedented move by asserting that, given the risks posed by extractive activities, Ecuador had a legal obligation to apply the precautionary principle as a corollary to the principle of non-contact, which itself is an expression of the rights to self-determination and consultation. The Court stated that:

“Even in the absence of scientific certainty about the impact of oil exploration and exploitation projects on their territory, effective measures should be adopted to prevent serious or irreversible damage, which in this case would be the contact of these isolated populations.” (para. 226)

This articulation is novel because it transforms the precautionary principle from a subsidiary interpretative tool into an enforceable obligation. In paragraph 227, the IACtHR went further by stating that Ecuador failed to “adequately guarantee” the precautionary principle in declaring a national interest in exploiting oil in their territories. This shift raises profound questions about whether the Court is stretching the meaning of a principle into a self-standing, justiciable legal standard.

Recontextualizing the Precautionary Principle

Legal theorists, drawing from Dworkin’s work, often distinguish between rules and principles. Rules tend to be rigid, binding commands, while principles function as flexible guidelines shaping the interpretation of rules. Traditionally, principles like precaution have complemented rules rather than standing as obligations in their own right. In the following lines, I will trace how the precautionary principle emerged from the environmental regime and then transferred onto the human rights realm through judicial hermeneutics, leading to the IACtHR’s consolidation as a quasi-rule. 

The precautionary principle emerged in international environmental law as a response to scientific uncertainty about environmental harm. It mandates that states take appropriate action even when conclusive evidence of harm is lacking. The principle gained prominence with Principle 15 of the  Rio Declaration, which asserts that the lack of full scientific certainty shall not be used as a reason to postpone cost-effective measures to prevent environmental degradation. This principle is also embedded in a plethora of international environmental treaties, most prominently enshrined in the United Nations Framework Convention on Climate Change and the 2001 Stockholm Convention on Persistent Organic Pollutants, emphasizing the inclusion of precautionary measures to anticipate, prevent, or minimize the causes of ecological damage.

In the realm of international human rights law, courts and tribunals have cautiously applied (pun intended) it in cases with environmental dimensions. In Tătar v. Romania (2009), the European Court of Human Rights (ECtHR) recognized for the first time the principle in assessing whether the state had taken adequate measures to prevent public health deterioration from sodium cyanide pollution from gold mining. Similarly, Cordella and Others v. Italy (2019) highlighted the state’s obligation to address environmental risks proactively. While the ECtHR has not always explicitly invoked the precautionary principle, it has increasingly incorporated its logic into environmental and public health protection rulings under the right to private and family life (Article 8 of the ECHR). More recently, in Cannavacciuolo and Others v. Italy, the ECtHR applies a precautionary approach to unprecedentedly affirm the existence of a protective state’s duty to investigate, identify and assess the nature and level of a risky activity to comply with its due diligence obligation conducive to the protection of the right to life (Article 2).

Unlike the ECtHR’s approach, which employed the precautionary principle to lower the threshold of what a ‘real and imminent’ risk between the source of environmental harm and the violation of the rights to life and private and family life entails, the IACtHR appears to have interpreted the principle as a justiciable right in itself. In considering the actions and omissions by the state that hindered the rights of PIAVs due to the expansion of extractive activities in the outer fringes of the intangible zone, the IACtHR stated that “in the process of declaring a national interest and its subsequent implementation, the precautionary principle was not adequately guaranteed, as no account was taken of information regarding sightings of PIAV in the territories where oil activities were to be carried out” (para. 227). Notably, the IACtHR chose to frame the precautionary principle as an obligation that Ecuador failed to guarantee while simultaneously resorting to the principle’s guidance function when the scope of the breached obligation is indeterminate. This oscillation between the direct justiciability of the principle and its gap-filling function might result from a slow but steady formation of the principle’s content in the Court’s case law.    

For the first time, the IACtHR developed the scope and content of the precautionary principle in its advisory opinion on human rights and the environment. The Court stressed that “in the context of the protection of the rights to life and personal integrity, […] States must act in keeping with the precautionary principle” “in cases where there are plausible indications that an activity could result in severe and irreversible damage to the environment, even in the absence of scientific certainty” (para. 180).

In La Oroya v. Peru, the IACtHR expanded the precautionary principle to include the right to life and personal integrity, as well as the right to health (para. 127). The Court considered that the absence of scientific certainty about the particular effects of environmental pollution on human health cannot be a reason for States to postpone or avoid adopting preventive measures. Moreover, apart from connecting the right to health as enshrined in Article 26 of the American Convention of Human Rights and the precautionary principle, the Court associates it with the intergenerational equity principle derived from the Rio Declaration and other international instruments (par. 128). This connection was reiterated in passing in the 2024 ruling in Pueblo U’wa v. Colombia (par. 295). 

The IACtHR, in a bold praxis of systemic integration, has thus taken the liberty to mould a principle engendered in a different regulatory regime according to the needs new cases demand, arguably to prevent a non-liquet or to fill the gaps of human rights incompatibility with risk management. The late ICJ and IACtHR justice Cançado Trinidade, who has contributed to the understanding of international legal principles applied to the environment,  has described the IACtHR’s engagement with the precautionary principle from a somewhat procedural aspect. He averred that in cases of grave human rights violations, the IACtHR has proceeded based on presumptions and inferences to shift the burden of proof in cases where the respondent State withholds the information and probationary elements concerning the alleged grave violations.

Cançado Trinidade’s depiction of the IACtHR applying the precautionary principle to reverse the burden of proof in severe human rights violation cases reflects a significant transformation toward a view of the principle as a self-standing, justiciable legal source, as established by the Tagaeri and Taromenane ruling. This boldness did not resonate unanimously among the judges, as evidenced by several dissenting opinions addressing the precautionary principle’s application. Justice Sierra Porto, in his partially dissenting vote, considered that the misapplication of the precautionary principle by the IACtHR lies in its reliance on a soft law instrument, namely the Guidelines for the Protection of Indigenous Peoples in Isolation and Initial Contact. Additionally, and more interestingly, Justice Sierra Porto argues that applying the precautionary principle to extractive areas that have not been exploited is a stretch, as it might lead to the inference that there is an obligation to prohibit any activity anywhere in the country where there may, at some point, be a presence of PIAV.

Similarly, Justice Pérez Goldberg, in her dissenting vote, argued that the IACtHR does not specify how the precautionary principle can be applied to collective property and self-determination rights. In her opinion, the Court fails to explain how the principle, which has been interpreted in previous case law only to the extent that the rights to life, integrity, and health have been encroached upon, is now extended to collective property rights. 

 The Challenges with Evidentiary Methods

One of the most contentious aspects of the case was the evidentiary method used to assess the impact of state actions on PIAV. Given that these Indigenous groups live in isolation, proving violations of their rights is particularly challenging, as they do not engage with legal systems or provide testimony. The Court, recognizing these challenges, relied on indirect evidence, particularly the experiences of neighbouring Indigenous groups, as a proxy to demonstrate the impact of oil exploration and territorial encroachment.

However, this approach was not without criticism. Justice Hernández, in her dissenting opinion, strongly contested the reliance on evidence from surrounding Indigenous communities. She argued that such an approach risks misrepresenting the realities of PIAV by assuming that the experiences of contacted Indigenous peoples are analogous to those of uncontacted groups. According to Hernández, anthropological studies should be the primary source of information for evaluating the conditions and rights of PIAV. In this case, she noted, no such studies were presented, raising concerns about the validity of the Court’s findings.

Additionally, Hernández warned against using the perspectives of neighbouring Indigenous groups as definitive proof of rights violations. She highlighted documented cases of conflict and competition between PIAV and other Indigenous communities, cautioning that using their testimonies could lead to biased interpretations. Given the absence of direct input from PIAV and the lack of rigorous anthropological studies, she concluded that the Court’s evidentiary approach was flawed and required greater methodological caution.

Concluding Remarks

The case of the Tagaeri and Taromenane is not just a liberal narrative about vulnerable peoples whose rights are being curtailed; it is far from it. Their story epitomizes the raw politics of draining resources from the proverbial periphery to the core in a world ecology shaped by unequal imperial exchange. It is a story that shows the tensions between the desire of a small country like Ecuador to build its nation-state through a developmental path reliant on oil extractivism and the resisting forces of Indigenous communities exerting ontological opposition. The unfathomable violence that members of these communities had to endure from religious missionaries, illegal loggers, neighbouring Indigenous individuals, settlers, oil infrastructure and the state not only mirrors similar colonial dynamics, it is also a reminder of the tactics of dehumanization of the capital class often deploys for accumulation at the expense of life.

Against the grim backdrop of a complex web of historical tragedies and injustices in a postcolonial developing nation-state like Ecuador, what tools do courts have to provide some level of redress for marginalized and racialized populations? Currently, the IACtHR, following its established approach in cases involving vulnerable communities in Latin America, has chosen to recontextualize the precautionary principle in light of human rights violations. This action could be viewed as something commentators have speculated on. Still, it is evident that the audaciousness of regional human rights courts is reflected in how they address the uncertainties in their realm by utilizing the tools of environmental law. 

Photo attribution: Untitled by CorteIDH / Rafael Luz/STJ is licensed under CC BY-SA 2.0.