On 14 November 2025, the High Court handed down judgment in the liability trial of Mariana v BHP, ruling that BHP UK and BHP Australia (or “BHP”) are strictly liable for the collapse of the Fundão Dam and liable based on fault. On the subject of limitation, the Court decided that the Claimants’ claims are not time-barred until September 2029 at the earliest. The Court also determined that the Municipality Claimants had standing to bring proceedings and made various findings as to the principles applicable to the proper construction of a sample set of settlement agreements for the purposes of determining, at a future stage, whether certain Claimants had waived their right to bring claims.
The Courts’ material findings on liability are addressed below.
BHP are strictly liable as polluters under the Brazilian Environmental Law
The Court found in favour of the Claimants’ case as to the proper interpretation and application of Articles 3, IV, and 14, paragraph 1, of the Brazilian Environmental Law, concluding that, for the purposes of environmental civil liability, a person or entity is a polluter where they are directly or indirectly responsible for a polluting activity and there is no conceptual distinction between those who are directly or indirectly responsible (at [379]). There is no fixed list of circumstances giving rise to the imputation of responsibility for a polluting activity, but the STJ case law indicates that such circumstances include (i) control over the activity; (ii) the creation of the risk of the activity; (iii) participation and/or active involvement in the activity; (iv) financing the activity; and (iv) economic benefit from the activity (at [380]).
Applying that interpretation, the Court concluded that BHP, together with Vale, were directly and/or indirectly responsible for the activity of Samarco for the following reasons:
- Samarco was “controlled and operated by BHP and Vale” (at [522]) and BHP (with Vale) were Samarco’s “directing mind” (at [522]-[526], [528]-[529]).
- BHP participated and was involved in the activities of Samarco “at every level” from “strategic decisions” to “detailed operational matters” (at [526] and [529]).
- BHP assumed responsibility for the assessment, control, mitigation and management of Samarco’s risks, including through audits of Samarco’s operations, the findings of which were monitored by BHP’s General Management Committee (at [527]).
- Samarco was an asset in which BHP substantially invested and from which it derived substantial financial and commercial benefits (at [530]).
As it was common ground that Samarco’s activity caused the environmental damage suffered as a result of the collapse, it followed from the Court’s findings that BHP were responsible for Samarco’s activity that BHP are strictly liable for the collapse (at [532]).
BHP are liable based on fault under Articles 186 and 927 (head paragraph) of the Brazilian Civil Code
The main dispute of law between the parties was as to the correct approach to liability by omission under Article 186 of the Brazilian Civil Code. Finding in favour of the Claimants, the Court determined that a legal duty giving rise to omissive liability need not be found in a specific written law, but may arise from different sources, including prior acts of the defendant such as the creation or contribution to a risk, or an assumption of responsibility for a risk (at [643]).
The Court concluded that the collapse was caused by BHP’s negligence. The Court’s material findings were as follows:
- BHP’s control over Samarco, their assumption of responsibility for risk assessment, management and control of the Dam, and their full participation in the Dam’s operations, gave rise to a legal duty to avoid harm (at [801]).
- The risk of collapse was foreseeable (at [1112]). BHP knew of the serious and ongoing deficiencies in the internal drainage of the Dam, the risk of collapse associated with those deficiencies and the recommended remedial measures, which, if performed, could have averted the collapse (at [661], [803] and [1112]).
- BHP allowed the saturation of tailings and the encroachment of slimes to develop; failed to carry out the recommended studies and remedial measures; and caused Samarco to continue to raise the height of the Dam (at [806]). These negligent, imprudent and/or unskilful failures caused the collapse (at [807]).
For those reasons, the Court held that BHP are liable based on fault under Articles 186 and 927 (head paragraph) of the Civil Code.
BHP are not liable under Article 927 (sole paragraph) of the Civil Code
The Court held that BHP are not liable under the general strict liability regime established by Article 927 (sole paragraph) of the Civil Code because this regime only applies where a special regime does not (at [534]). As it was common ground that the Environmental Law is a special regime which applies in cases of environmental damage, it followed that the general strict liability regime did not apply (ibid).
BHP are not liable under the Corporate Law
The Court held that BHP are not liable under Articles 116 and 117 of the Corporate Law because, although BHP are a controlling shareholder within the meaning of Article 116 (at [636]), Article 116, sole paragraph, does not impose any duty owed directly to, or actionable by, third parties (at [637]-[638]).
Grace Ferrier acted for the Claimants, instructed by Pogust Goodhead, together with Alain Choo Choy KC, Andrew Fulton KC, Nicholas Harrison, Jonathan McDonagh, Russell Hopkins, Ibar McCarthy, Antonia Eklund, Anisa Kassamali and Hannah Taylor.
