The Brazilian governments under Presidents Lula and Rousseff pushed forward an exporting extractivist economy largely based on iron ore exports by the Vale S.A. company (formely Vale de Rio Doce) and also on soybean exports. To the Brazilian policy makers (both in government and in the neoliberal opposition) the tailings dams failure at Samarco's Germano mine (Samarco is owned by Vale and BHP Billiton) in Mariana (not far from Ouro Preto), in Minas Gerais’ iron belt on 5th November 2015 was something of a shock. This is one of the largest iron ore mines in the world. The Rio Doce (the Doce River) was polluted for over 700 km downstream. The burst dam unleashed 50 million cubic meters of mud on the valley killing 19 people and wiping out the village of Bento Rodrigues and reaching very quickly Barra Longa and other villages. About 800 people lost their homes. Many villages downstream were left without drinkable water. The discharges were mainly composed of iron oxide and silica, but IBAMA reports indicate their toxic potential by the presence of heavy metals [14].

Dilma Rousseff compared the Samarco disaster with the BP 2010 Deepwater Horizon spill in the Gulf of Mexico. She said that Samarco’s shareholders — BHP Billiton, the Anglo-Australian company, and the Brazilian iron ore exporter Vale — would pay for the accident but the figures mentioned by Roussef were pitifully low, not billions but tens of millions of dolars. The Financial Times reported that there was concern over the size of liabilities associated with the accident. An analyst at Citi said that: “It could possibly cost BHP more than $1bn with the clean-up costs, potential fines from government and compensation to families.” [9]. BHP Billiton has 50% share in Samarco.

The Unions had complained that Vale was lowering safety standards.

Workers feared for their safety after the Samarco dam burst, where the company was reducing the number of employees because of weak ore prices, despite its push for output and complaints about safety. Ronilton Condessa, secretary of the Metabase labor union in Mariana, where Samarco is the main employer, told Reuters that nearly 400 mine workers were dismissed in 2015 from Vale's mining complex of Mariana, even as it squeezed more productivity from the workforce to offset the drop in revenue from iron ore sales to the global steel industry. The company unearths 10 percent of its total iron output of roughly 340 million tonnes a year there. Vale has four mines in the Mariana Complex around Samarco: the Algeria, Fabrica Nova, Vazendao and Timbopeba mines, where it employs 3,000 people. The Metabase union represents workers at the first three of those mines [10].

Vale had been pushing output to record levels in the face of sagging prices, as it is fighting for the No. 1 slot in iron ore against its Australian rivals BHP and Rio Tinto. "Hiring is happening only in exceptional cases," Condessa said. He said union members have complained about undue pressure to ramp up production [10].

The MAB (movement of “atingidos por barragens”) and the International Articulation of “Atingidos pela Vale” issued statements [4, 5]. The latter said, “The rupture of a tailings dam – a structure that is intended to retain the solid waste, which has a high level of toxicity and water from ore beneficiation processes – does not occur randomly and is not new in the state Minas Gerais, nor in the mining sector. The severity of the case requires rigorous investigation into the incident, strict accountability of perpetrators and full redress and compensation to all affected”. Pollution would reach the state of Espírito Santo and the sea, through the Rio Doce. They added that what happened was a crime. The regulatory agencies and companies had full responsibility for the tragedy. The amount of waste proved that companies had passed the dam’s capacity. The technical report conducted by the Instituto Prístino at the request of the public prosecutor during the licensing of the project had already identified problems, such as the dam of Fundão (that failed) and the waste dump Union Fábrica Nova Mine Vale which border on each other, with overlapping areas of direct influence [5].

Indigenous Krenak people cut the railway from Minas Gerais to the harbour Vitoria in Espírito Santo for a few days to complain against the pollution of the Rio Doce. This is a route followed by the iron ore for export [1, 2]. For the Krenaks, the Rio Doce was source of their subsistence and also a sacred entity [15]. In January 2016, the Tupinikim and Guarani Mbyá indigenous also protested on the Vitória-Minas Railroad (EFVM) in order to draw attention to the impacts on their communities. The protests also contributed to their recognition as being affected by the disaster [16].

In March 2016, the Brazilian federal government and the state governments of Minas Gerais and Espírito Santo signed a "Term of Transaction and Adjustment of Conduct" (TTAC) with Samarco, Vale and BHP. The agreement determined the reparation measures, which would have an estimated cost of US$ 5 billion to be applied over 15 years, and the creation of the Renova Foundation to manage the reparation and compensation actions [11]. However, the negotiations that led to this agreement completely ignored the populations affected by the disaster [18]. According to a statement of “Atingidos pela Vale”: “The agreement signed between Samarco, Vale and BHP, the states of Minas Gerais and Espírito Santo and the federal government was the result of the power of the companies and the interest of the State in speeding up alleged remedial measures and hiding their responsibilities. The political influence of companies and the complicity of the State tried to affirm a minimal agreement of mitigation of the impacts, that ignored the participation of the victims of this great disaster.” [17].

The TACC was also criticized by the Federal Public Defender's Office (DPU) and the Public Prosecutor's Office of Minas Gerais and the Federal Public Ministry. The latter filed a Public Civil Action in May 2016 against Samarco, Vale and BHP, and against the Union and the States of Minas Gerais and Espírito Santo so that they would be required to fully repair the social, economic and environmental consequences of the disruption. The repair value was estimated at $ 43.8 billion (based on the Deepwater Horizon disaster figures). Another Public Civil Action of US$ 5 billion against the companies had been filed in 2015 by the Federal Government, but would be extinguished with the approval of the agreement. Finally, the TACC was ratified in May 2016, but suspended by the Supreme Court of Justice (STJ) on July 2016 [11, 13].

In January 2017, a Preliminary Adjustment Term (TAP), with the participation of affected communities, defined the hiring of research centers to carry out specialized expertise and evaluate the impacts of the tragedy. In 2018, a new Adjustment and Conduct Term was elaborated, which was called Governance TAC, which considered the increase of the participation of the victims in the processes of deliberation related to reparations and in the Renova Foundation. With the approval of the agreement, the Public Civil Action of $ 43.8 billion was provisionally suspended for up to two years [13]. This new agreement was criticized by the “Movimento dos Atingidos por Barragens” for having been rebuilt without dialogue with those affected by the disaster, despite some advances in participation, and for keeping them as minorities in all decision-making bodies [12].

The Federal Police (PF) and the Minas Gerais State Public Prosecutor presented a criminal proceeding related to the disaster at the beginning of June 2016. In the ongoing proceeding, 22 people – members of the Board of Directors of Vale and BHP, directors and managers of Samarco, representatives of Vale and BHP in Samarco and engineers of VogBR Consulting – are charged with murder, flooding, collapse, bodily injury and environmental crimes. In this same criminal proceeding, VogBR is responsible for the crime of filing a false environmental report, and Samarco, Vale and BHP Billiton are accused of nine environmental crimes [20].

In 2014, Samarco produced 25 million tons of iron ore in Mariana, and a similar amount of waste. Production increased 9 million tons over previous year, to compensate for lower prices.

Some early reports cited in The Financial Times put the liability for the tailings dams failure at one billion USD. The legal developments (including criminal charges) and the amounts of money being considered for compensation (exceeding USD 40 billion) are described above, under Source of Conflict.