Municipio de Mariana & Ors v BHP Group (UK) Ltd & Anor

On an application for permission to appeal, the Court of Appeal should not re-try findings of fact, expert evaluation or foreign law. Absent a compelling reason, it should assume that the trial judge considered all material evidence; failure to mention a document or argument does not establish a procedural irregularity. A judgment must identify the issues, marshal relevant evidence and explain decisive preferences, but need not address every underlying document or submission. This restraint is especially important in a lengthy TCC trial involving interlocking factual and expert evidence. Permission was refused on challenges to strict and fault-based liability and Brazilian limitation findings. Expedition was granted for the separate costs appeal because early resolution served the overriding objective.

More than 600,000 Brazilian claimants brought claims against BHP arising from the collapse of the Fundão Dam in Brazil. Following earlier jurisdictional proceedings, O’Farrell J’s liability judgment at [2025] EWHC 3001 (TCC) found for the claimants on numerous issues under Brazilian law, including liability and limitation.

In a consequentials judgment at [2026] EWHC 73 (TCC), the judge refused permission to appeal except on a costs-interest issue. BHP applied to the Court of Appeal for permission on five substantive grounds, alleging errors of law and fact and serious procedural irregularity, principally a failure to engage with its case. BHP also sought expedition because of the proposed Stage 2 trial. The central questions were whether any substantive ground was reasonably arguable or otherwise compelling, and whether the costs appeal should be expedited.

1. Disposition. Permission to appeal was refused on every element of Grounds 1 to 5, concerning strict liability, fault-based liability and limitation. Expedition was ordered for the separate costs appeal. Lewison LJ agreed.
2. Appellate restraint. The principles in FAGE UK Ltd v Chobani UK Ltd [2014] EWCA Civ 5 and Volpi v Volpi [2022] EWCA Civ 464 apply. The Court should not interfere with primary facts, evaluative findings, inferences or expert assessments unless the decision was plainly wrong, irrationally insupportable or one no reasonable judge could have reached. It must assume, absent a compelling reason, that the trial judge considered the whole of the evidence. Minute textual analysis, island-hopping through documents, reweighing evidence and treating a judgment as though it were a contract or statute are impermissible.
3. There is one permission test across the High Court, including the TCC. Nevertheless, the factual and expert-evidence hurdle is particularly high in a lengthy specialist trial involving detailed, interlocking evidence: Wheeldon Brothers Waste Ltd v Millenium Insurance Co Ltd [2018] EWCA Civ 2403. Foreign law is treated as fact in English proceedings. Where, as here, the foreign legal system is materially removed from the common law, the trial judge has a substantial advantage in assessing expert evidence; there is no greater appellate scope to interfere: Perry v Lopag [2023] UKPC 16.
4. Engagement with the case. A judgment must contain the basic building blocks of a reasoned process, including identification of issues, relevant evidence and reasons for decisive preferences. In expert cases, this ordinarily requires explaining which expert evidence is preferred and why, not addressing every underlying document. The trial judge had plainly engaged with BHP’s case. The alleged expert concession was not established on a fair reading of the evidence. The multifactorial approach under Article 3(IV) of the Environmental Law was therefore the correct approach, and the challenges to control, responsibility and causation were factual and not reasonably arguable.
5. The trial judge had also addressed the alternative fault-based case under Article 186 of the Civil Code, the alleged causal link under Article 403, the constitutional and corporate provisions relied upon, and the competing expert evidence. The pleading objections were considered and rejected. In a complex TCC trial, the agreed list of issues defines the matters for determination and effectively supersedes the pleadings as the operational framework. The objections were in any event pleaded, tested in evidence and unsupported by demonstrated prejudice.
6. The limitation challenges failed for the same reasons. The judge had addressed the arguments concerning Article 200 of the Civil Code, Article 27 of the Consumer Defence Code and the 1932 Decree. No compelling reason or reasonably arguable error was shown. The English trial findings could not bind Brazilian courts on Brazilian law.
7. For completeness, if an unfair trial were established, a proper retrial, potentially including oral evidence, might be required; transcripts could not automatically substitute for the trial judge’s assessment of witnesses. This observation, informed by Serafin v Malkiewicz [2020] UKSC 23, was not necessary to the disposition.

• Court of Appeal (Civil Division): Permission to appeal on Grounds 1–5 was refused. Expedition was ordered for the separate appeal concerning interest on costs.
• High Court, Technology and Construction Court: O’Farrell J’s liability judgment at [2025] EWHC 3001 (TCC) found for the claimants on numerous issues. The consequentials judgment at [2026] EWHC 73 (TCC) refused permission on the substantive grounds but granted it on the costs-interest ground.
• Court of Appeal: An earlier strike-out decision was overturned at [2022] EWCA Civ 951. A later contempt appeal in the same litigation was allowed at [2026] EWCA Civ 294.