Mariana Dam Collapse: No re-run for BHP as Liability Judgment stands
On 5 November 2015, the Fundão Dam in Southeast Brazil collapsed, releasing millions of tonnes of liquefied ore tailings into the environment in a catastrophic flow slide. 10 years later, in November 2025, the English High Court issued a landmark ruling holding the global mining company, BHP Group (UK) Limited and BHP Group Ltd (together “BHP”), liable for this disaster (the “Liability Judgment”).
Background
The claim is brought on behalf of more than 600,000 individuals, including Indigenous and Quilombola community members, municipalities, faith-based institutions, businesses, and utility companies who suffered both environmental and socio-economic damage as a result of the dam collapse and subsequent flow of liquified iron ore tailings. We considered the impact of the Liability Judgment on cross-border litigation in a previous blog post.
Following the Liability Judgment, BHP applied for permission to appeal to both the English High Court and subsequently the Court of Appeal. On both occasions, permission to appeal was refused, save for one issue regarding interest on costs in the English High Court. This blog examines the Court of Appeal’s judgment, delivered on 6 May 2026 (the “Appeal Judgment”) and, in particular, how it serves as a welcome reminder that an appeal is not an opportunity to re-open and re-try a case simply because a party disagrees with the outcome at first instance.
The Appeal
The central basis of the appeal was not merely that the trial judge had made discrete errors requiring correction on appeal. Rather, BHP argued that “something had clearly gone wrong in the judicial process”, such that the Liability Judgment required full appellate scrutiny. In particular, BHP alleged that the judge had failed to engage with BHP’s case, and this failure amounted to a serious procedural irregularity.
The alleged failures differed across the various grounds. The Appeal Judgment therefore considered five grounds of appeal brought by BHP, concerning both the bases for liability and relevant limitation periods.
Grounds 1 - 2: Liability
- Strict liability: Ground 1 challenged the finding that BHP was strictly liable for the Dam’s collapse based on their ownership and/or control of Samarco, whose activities were found to have caused the collapse. BHP argued that this was the wrong test, and that only an operator of the activity (in this case, Samarco) could be held liable as a polluter under Brazilian environmental law.
- Fault-based liability: Ground 2 was an alternative basis of liability advanced by the claimants and would only become material if the strict liability finding were overturned. BHP challenged the finding that it was liable for negligent or imprudent acts or omissions.
Grounds 3 - 5: Limitation
Grounds 3 - 5 concerned the applicable limitation period and challenged the findings that (a) the limitation period was suspended and (b) the claims brought by both claimants and municipalities were subject to a five-year limitation period. BHP argued that the judge had both failed to engage with the determinative issues and erred in foreign law/fact in relation to the findings on those issues.
The Court of Appeal refused permission to appeal on all five grounds, finding that the trial judge had engaged sufficiently with BHP’s case, entitling them to reach the conclusions they did, and no serious procedural irregularities had occurred.
Analysis of the Appeal Judgment
The Appeal Judgment provides insightful commentary on the bar to successfully appeal a case which involved significant evidence, including evidence of foreign law.
The Appeal Judgment rejects BHP’s argument that the trial judge’s alleged failure to engage with its case amounted to a serious procedural irregularity. It confirms that, absent compelling reasons to the contrary, an appellate court should assume that the trial judge considered all the evidence and arguments before them and that a judge’s failure to refer in the judgment to every piece of evidence or submission does not mean it was overlooked. The Appeal Judgment notes that the alternative approach would be contrary to the overriding objective. This is particularly relevant in large, complex cross-border cases involving extensive evidence.
The Appeal Judgment also provides a useful reminder that the role of an appellate court is not to allow a party to re-run its factual case under the guise of an appeal. In doing so, the Court of Appeal criticised part of BHP’s application to appeal as “verging on a full re-run of closing submissions” and its selection of documents as “island-hopping”.
This point was reinforced by the fact that the relevant issues were governed by Brazilian law. In English proceedings, issues of foreign law are treated as questions of fact, meaning that BHP faced the high threshold applicable to appeals on factual findings. Applying the principles in FAGE UK Ltd v Chobani, the Court emphasised that, absent a compelling reason to the contrary, an appellate court should assume that the trial judge considered the whole of the evidence; the omission of a particular piece of evidence or argument from the judgment does not mean it was overlooked. That approach carried particular force in this case, where the trial judge had heard extensive expert evidence on Brazilian law, and the appellate court was in a significantly worse position than the trial judge to evaluate that evidence.
The Appeal Judgment is therefore significant beyond its treatment of the individual grounds of appeal. It puts a marker down showing not only the willingness of English courts to adjudicate environmental harm occurring abroad, but the ability of trial judges to engage with both substantive and procedural aspects of foreign law, and the extensive evidence put before them in cross-border environmental litigation, without the appellate process becoming a vehicle through which dissatisfied parties can seek effectively to re-open or re-try the case at second instance.
Next steps
With the Liability Judgment now final, the next stage in the proceedings will consider causation, loss, and damage, with this stage of the trial due to commence in April 2027.
With thanks to paralegals Sarah Dent Cullen and Vicky Tsouki for their contributions