The Mercedes-Benz NOx Emissions Group Litigation Aurora Cavallari & Ors v Mercedes-Benz Group AG & Ors

Where disclosure has already been ordered, a party may redact material that is irrelevant, but the right to redact must not be interpreted too restrictively or applied without adequate transparency. In technically complex litigation, rational and comprehensible evidence from an opposing expert that information is relevant should receive considerable weight. The court will generally err on the side of disclosure where disclosure remains proportionate and confidentiality can be protected. Heavy redaction may justify closer scrutiny, further explanation, confidential inspection or a supervised review. Descriptive information that enables experts to understand the material should ordinarily be disclosed where it is not independently confidential or where confidentiality is adequately protected.

The claimants applied to vary disclosure orders made on 19 January and in March 2024 concerning A2L files accompanying identified Mercedes firmware versions. The orders permitted irrelevant material to be extracted or redacted and required disclosure in stages agreed between the parties.

The parties disputed whether the agreed second stage had been completed, whether descriptions, function names and chapter headings could be redacted, whether further data and parameters had been withheld too broadly, and whether the number of files ordered should be reduced after sample vehicles had been selected. The central issues were the proper scope and supervision of redactions and whether the existing disclosure orders should be varied.

1. Compliance with existing orders. The agreed two-stage process formed part of the relevance parameters required by the January order. The Mercedes Defendants had not complied with the January or March orders because the second stage had not been completed.
2. Redactions and transparency. The court accepted that the percentage of redacted material, taken alone, did not establish that the approach was inappropriate. However, descriptions, function names and chapter headings should not be treated as irrelevant or confidential for disclosure purposes. They were necessary to provide transparency about the basis on which associated data and parameters had been redacted. Disclosure into a confidentiality ring removed any substantial prejudice from providing that information.
3. Technical relevance. The specification functionalities identified by the claimants’ evidence were more likely than not to be relevant to expert investigation. The generic pleadings and the asymmetry of information justified an expansive approach to relevance. Where an expert’s evidence that information is relevant is rational and comprehensible, it should receive considerable weight. The court will generally err on the side of disclosure in technical disputes, provided disclosure remains proportionate and confidentiality concerns are accommodated.
4. Review process. The Mercedes Defendants were permitted to continue redacting data and parameters considered irrelevant, but had to disclose all descriptions and headings. They were required to review existing redactions using a more expansive view of relevance. The review was to be supervised and verified by a solicitor. Any dispute was to be crystallised swiftly and brought before the court.
5. Number of files. There was no basis to vary the number of files required by the January and March orders. The files could assist with testing heterogeneity and the representative nature of the selected firmware samples, and consistency with other group litigations supported retaining the existing scope.