Município De Mariana & Ors v BHP Group (UK) Limited (formerly BHP Group PLC) & Anor

Permission to amend a statement of case depends on the overriding objective and requires a balance between prejudice to the applicant, the opposing parties and other court users. The proposed case must be arguable, coherent and sufficiently particularised. Lateness is relative, but a very late amendment which threatens a fixed trial date faces a heavy burden. Pleadings must identify the material facts, decisions and conclusions relied upon; parties cannot rely on extensive document lists while leaving the opposing party to discover the case for itself. Where a specific amendment is sufficiently clear and its additional work can be accommodated without unfair prejudice or loss of the trial date, permission may be granted. Different amendments may properly receive different treatment within the same application.

The claimants brought extensive Brazilian-law claims arising from the collapse of the Fundão Dam in Brazil. A trial of threshold liability and limitation issues had been fixed for October 2024. The claimants applied to amend their Re-Amended Master Particulars of Claim and Amended Reply, including amendments concerning Brazilian law, BHP’s alleged knowledge and involvement, heads of loss, limitation, settlement agreements, releases and waivers.

The defendants and Vale opposed substantial parts of the application on grounds including lateness, inadequate particularisation, additional expert and factual work, and risk to the trial timetable. The central issues were whether the proposed amendments were sufficiently arguable and clear, and whether the resulting prejudice and procedural burden justified refusing permission.

The application was allowed in part and refused in part.

1. Applicable principles. Under Civil Procedure Rules 1998, rr 17.1 and 17.3, amendment requires consent or permission and falls within the court’s general discretion. Applying the principles stated in CIP Properties (AIPT) Ltd v Galliford Try Infrastructure Ltd [2015] EWHC 1345 (TCC) and Quah Su-Ling v Goldman Sachs International [2015] EWHC 759, the court had to balance injustice to the applicant against prejudice to the opposing parties and other litigants. The proposed amendment had to be arguable, coherent and properly particularised. Lateness depended on the nature of the amendment, the explanation for its timing and its consequences. A very late amendment threatening a fixed trial date attracted a heavy burden.
2. Brazilian law amendments. The proposed amendments were arguable, cogent and sufficiently detailed. The additional work for the legal experts was significant but not oppressive, and the trial date remained achievable. Permission was therefore granted.
3. Factual amendments. Paragraph 196A was refused. It listed numerous meetings, reports, visits and communications without stating the knowledge, decisions, conclusions or significance said to arise from them. The pleading did not identify the case BHP had to meet, and the claimants could not require BHP to trawl through documents to formulate it. Paragraph 205A and associated amendments were allowed because they pleaded a specific case concerning knowledge of defects and drainage problems, approval and funding of the relevant works, and the risk of collapse. They were sufficiently clear and could be accommodated without unfair prejudice.
4. Other amendments. Amendments to heads of loss were allowed, with the defence to those matters deferred until after the first-stage trial. Amendments concerning limitation, settlement agreements, releases, waivers and misleading monitoring reports were also sufficiently clear and imposed no unreasonable additional burden.
5. The claimants were ordered to bear the costs of and occasioned by their amendments. The application costs were costs in the case. The parties were directed to agree a realistic timetable for consequential steps.

The judgment records earlier decisions in the same proceedings, including the Court of Appeal decision at [2022] EWCA Civ 951 and earlier High Court decisions at [2022] EWHC 330 (TCC), [2023] EWHC 1134 (TCC) and [2023] EWHC 2030 (TCC). This was a first-instance decision on the claimants’ amendment application.