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1 Jan 2015

Grupo México lawsuit (re Buenavista del Cobre toxic spill in Mexico)


Date lawsuit was filed
1 Jan 2015
Date accuracy
Year Correct
Location of Filing: Mexico
Location of Incident: Mexico
Type of Litigation: Domestic


Grupo México Mexico Construction, Railroad, Engineering, Mining
Grupo Higa Mexico Building materials & equipment, Cement, Construction, Road-building, Property development, Printing & copying



Following a toxic spill of 40,000 cubic meters of chemicals from the Buenavista del Cobre mine, a subsidiary of Grupo México, into the Sonora and Bacanuchi rivers in August 2014, affected community members filed lawsuits against government agencies, the Buenavista del Cobre mine and the trust fund established to cover the costs of remediation and reparation. The Supreme Court dismissed the case against the Buenavista del Cobre mine ruling that as a private entity, the company could not be sued under the constitutional complaint mechanism (amparo) used by the plaintiffs. In January 2020, the Supreme Court declared the trust fund set up to compensate communities a responsible authority and granted its reactivation until total reparation of damages caused by the spill.

Factual background

On 6 August 2014, 40.000 m3 of chemicals  from the Buenavista del Cobre mine, a subsidiary of Grupo México, spilled into the Sonora and Bacanuchi rivers.  The toxic spill caused water and soil contamination which affected approximately 22,000 people directly and 250,000 indirectly across seven municipalities.  Affected communities allege they suffer health damages, loss of livestock and crops, and restricted access to drinking water as a result of the spill.  The company initially blamed the spill on intensive rains, but later on admitted that the incident occurred due to defects in the piping system.

The environmental agency SEMARNAT immediately ordered an investigation into the incident.  On 29 August 2014, the Federal Attorney's Office for Environmental Protection (PROFEPA) filed a petition at the Attorney General's Office requesting a criminal investigation.  Between September and October 2014, PROFEPA issued a series of reports concluding that the spill occurred as a result of the company’s negligence and use of inadequate equipment.  The company was subsequently ordered to pay four different fines related to over 55 environmental and safety violations, amounting to a total of about $1.8 million.

On 15 September 2014, government authorities and Grupo México signed an agreement establishing a trust fund (Fideicomiso Río Sonora) with an initial balance of 2 billion Mexican pesos to cover the costs of environmental and agricultural remediation projects and provide compensation for economic damages and health problems to the community members affected by the spill. Additionally, Grupo México committed to installing 28 water treatment plants in affected areas and to build a medical clinic. Community members expressed concerns about the lack of consultation and arbitrariness of decisions surrounding the allocation of funds, as well as the lack of transparency regarding the results of the impact assessment.

Legal argument

In 2015 and 2016, affected communities filed 12 different complaints against government agencies under the 2013 law on the constitutional complaint mechanism (amparo), in relation to the various damages caused by the spill, as well as regarding denial of access to information on the incident. The claims concerned alleged violations of communities’ right to work, property, healthy environment, access to water, compensation for damages and participation in public matters. Lawsuits also concerned alleged government failure to ensure compliance with environmental and safety regulations and to implement remediation plans, as well as failure to adequately consult the communities regarding decisions affecting them.

Legal proceedings

In April 2016, the communities also filed a petition under the Foreign Legal Assistance Status to the US District Court in Arizona, requesting information from the US-headquartered Southern Copper, Buenavista del Cobre´s parent company, related to the mine’s operations and environmental practices. This information was deemed important to help determine the cause of the spill.  In August 2016, the court granted the discovery petition and ordered Southern Copper to provide the requested information.

On 6 August 2017, the First Tribunal of the Sonora State district ruled in favour of the plaintiffs in a lawsuit regarding the government’s failure to attend to health problems caused by water contamination.  However, the Supreme Court of Justice dismissed a case that named Buenavista del Cobre as one of the defendants and alleged failure to comply with environmental norms and lack of adequate regulations on treating hazardous waste.  The court ruled that that the company could not be qualified as a responsible authority under the 2013 amparo law and held liable for human rights violations.  According to the law, as a general rule, only public authorities can be parties to an amparo. However, private persons can be qualified as a responsible authority if they perform acts equivalent to those of a public authority, and when those acts are prescribed by law and affect the exercise of human rights.  The plaintiffs claimed that Buenavista del Cobre must be treated as a responsible authority for the purpose of the case based on its obligation, established in the mining regulation, to ensure environmental protection.

In October 2016, several UN Special Rapporteurs urged the Mexican Government to provide information on the real impact of the spill and on the measures taken to mitigate its consequences. In April 2017, the UN Working Group on business and human rights noted in its country visit report that the government and Grupo México failed to fulfil their obligations under the initial trust fund agreement, and that the Attorney General has not taken action on the petition to open a criminal investigation.  In turn, the company claimed they could not fulfil their obligations regarding the construction of water treatment plants and health clinic “because the municipal authorities did not have capacity to operate them”.  In August 2017, it was revealed that the trust fund had been closed.  The government claimed that the remedial and compensation plans had been fully complied with.  However,  affected communities argue that Grupo México and the Mexican Government have not fulfilled their obligations under the trust fund in a lawsuit pending before the Supreme Court of Justice.  The court is yet to decide if Fideicomiso Río Sonora can be tried in court for human rights violations under the 2013 amparo law, as an entity composed of both public and private actors.

On 5 September 2018, the Supreme Court of Justice of Mexico ruled in favour of the members of the Bacánuchi rural community in a lawsuit challenging the construction of a new tailings dam in the Sonora river basin by Grupo México's subsidiary Buenavista del Cobre, recognizing the right of the community members to be consulted on environmental matters of public interest.

Latest update

On 8 January 2020, the Supreme Court of Justice of Mexico issued a ruling on these three cases related to the Rio Sonora Trust filed by the Sonora River Basin Committees regarding the extinction of the trust, the way the trust operated and the lack of conclusion of the remediation programme. The Supreme Court declared the Sonora River Trust the responsible authority to carry out the remediation programme and has granted its reactivation until the total reparation of the damages caused by the spill is completed.


- [ES] El Supremo mexicano abre una nueva vía para las víctimas de un derrame minero en Sonora, El País, 5 Apr 2020
- Mexican Supreme Court ruling favors communities regarding new Southern Copper Corporation tailings dam: PODER, Global News Wire, 7 Sep 2018
- [ES] "Suprema Corte falla a favor de Bacanuchi contra presa de jales mineros", El Economista, 5 Sep 2018
- [ES] "Comités de Cuenca Río Sonora y FPDT-Atenco se unen para exigir a SCJN derecho a participación ante megaproyectos", ProDesc, 20 Aug 2018
- [ES] "ONG piden a la SCJN reconocer derecho ciudadano a participar en proyectos que afecten al ambiente", Proceso, 14 Aug 2018
- [ES] "Relator ONU: Grupo México, ejemplo descarado y flagrante de impunidad", Milenio, 8 May 2018
- [ES] "Atrae la SCJN dos casos relacionados con el derrame en el Río Sonora", Red TDT, 26 Apr 2018
- [ES] “Buscan transparentar el Fideicomiso Río Sonora”, ContraLínea, 23 April 2018
- “Sonora spill projects remain incomplete”, Mexico News Daily, 8 August 2017
- [ES] "Promesas incumplidas y pozos envenenados: así vive la gente cerca del contaminado Río Sonora", Animal Político, 2 Aug 2017
- [ES] “LA suprema corte atrae demanda contra grupo Mexcio por derrame de 2014”, Expansion, 5 July 2017
- “Billionaire German Larrea's Grupo Mexico Failed Victims In Mining Disaster, UN Says”, Forbes, 27 July 2017
- [ES] ”Gobierno y Grupo México eluden remediar ecocidio en Sonora: ONU”, La Jornada, 26 July 2017
- [ES] "Nueva demanda contra Grupo México por derrame de tóxicos en Sonora", Proceso, 28 Oct 2015
- [ES] "Segunda demanda colectiva para Grupo México", La silla rota, 25 June 2015
- [ES] "Con llagas y metales en la sangre: así dejó Grupo México a gente en Sonora", SinEmbargo, 22 June 2015
- [ES] "Grupo México envenena Sonora; la minera cerró un hospital general", Excelsior, 26 May 2015
- “Mexico’s ‘worst environmental disaster in modern times’”, , 8 January 2015
- “No Apology From Mining Tycoon German Larrea For Worst Ecological Disaster In Mexico's History”, Forbes, 2 Sep 2014


- [ES] Suprema Corte concede amparo a las comunidades en relación al cierre del fideicomiso Río Sonora, 15 Jan 2020
- "Update on Grupo México lawsuit (re toxic spill in Mexico)", 27 Aug 2018
- [ES] "Suprema Corte decidirá si comunidades pueden participar en asuntos que afectan el medio ambiente", 13 Aug 2018
- [ES] "Derecho a participar en asuntos medioambientales: Amparo en revisión 365/2018 en la Segunda Sala de la Corte", 9 Aug 2018
- [ES] "Relator de la ONU sobre sustancias tóxicas expresa su preocupación por la salud de afectados por derrame en el Río Sonora", 6 May 2018
- [ES] “Derrame de 40 millones de litros de solución de cobre acidulado a los ríos Bacánuchi y Sonora provenientes de las instalaciones de la mina Buenavista del Cobre, S.A. de C.V., subsidiaria de Grupo México: Informe para el Relator Especial sobre las obligaciones de derechos humanos relacionadas con la gestión y eliminación ecológicamente racionales de las sustancias y los desechos peligrosos, Sr. Baskut Tuncak”, May 2018
- [ES] “Comités de cuencia río Sonora se amparan contra zona económica especial y demandan a instancias de gobierno por no atender su salud”, 2 Aug 2017
- [ES] “Los comités de cuenca río Sonora anuncian victorias legales en Estados Unidos”, 5 Aug 2016
- “KPBS televisión video about the effects of the río Sonora spill”, Nov 2015
- [ES] “Conferencia de prensa: Comités de cuencia rÍo Sonora obtienen primeras victorias legales”, Oct 2015
- [ES] “Comités de cuencia rÍo Sonora obtienen primeras victorias legales”, 22 Oct 2015
- [ES] "Ante la omisión de las autoridades deferales y la empresa Grupo México, Comités de Cuenca del Río Sonora presentan 5 amparos", 4 Aug 2015

Earth Rights

- “Mexico’s Worst Mining Disaster Survivors Turn to U.S. Court for Assistance”, EarthRights International, 11 April 2016

UN Document

- “Report of the Working Group on the issue of human rights and transnational corporations and other business enterprises on its mission to Mexico”, UN General Assembly, 27 April 2017

Court documents

- [ES] Supreme Court rulings on the appeals for protection by community members, 384/2018, 640/2019 y 927/2018, Suprema Corte de Justicia de la Nación, 18 Jan 2020