SIEMENS MOBILITY LIMITED v HIGH SPEED TWO (HS2) LIMITED

Expert evidence in procurement and judicial review proceedings is exceptional. It must be shown to be reasonably required to resolve a pleaded issue, rather than to reassess the technical merits of a tender or substitute expert opinion for the court’s judgment.

Evidence may be permitted where discrete and complex technical issues require explanation that cannot be obtained from agreed material, factual evidence and documents, or where it is necessary to assess an alleged manifest error. It remains inadmissible where experts would descend into the arena or determine whether the public authority’s decision was rational or lawful.

Siemens challenged HS2’s procurement of rolling stock and related train services contracts under the Utilities Contracts Regulations 2016. The proceedings included procurement and judicial review claims concerning the successful joint venture’s compliance with technical specifications, dwell-time requirements, evaluation and proposed design modifications.

Siemens sought permission under CPR 35.4(1) for each party to rely on an independent expert in rolling-stock dwell time, door and seat configuration, and the platform interface. HS2 and the interested parties opposed the application. The central issue was whether such evidence was reasonably required to resolve any pleaded issue at trial.

The application for permission to rely on expert evidence was dismissed.

1. Applicable principles. Expert evidence must be restricted to evidence reasonably required to resolve the proceedings under CPR 35.1. Experts may address relevant technical matters within their expertise, but may not usurp the court’s function under section 3(3) of the Civil Evidence Act 1972. The court is to determine the issues, not conduct a trial by expert.
2. In procurement and judicial review claims concerned with compliance with procurement requirements, manifest error or unfairness, expert evidence will generally be unnecessary. The court reviews the procurement process and decision, rather than reassessing the technical merits of competing tenders. Evidence may nevertheless be allowed where discrete, complex technical issues require explanation that cannot be obtained from factual witnesses and documents, or where it is necessary to determine an alleged manifest error.
3. The party seeking permission must identify the particular technical issues, the proposed evidence’s nature and scope, and why it is required to resolve the dispute. Expert evidence is inappropriate if it would involve opinions on the ultimate rationality, lawfulness or correctness of the public authority’s decision.
4. None of Siemens’s five proposed categories met that test. The meaning and modelling assumptions for dwell time were defined by the tender documents and were not pleaded issues. Independent expert assessment of compliance with the technical specifications would impermissibly reassess the tender’s merits. The Arup modelling did not form part of the tender evaluation. The alleged effects of design modifications concerned whether HS2 had undertaken an impact assessment, which could be determined from the documents and pleaded case. No adequately particularised technical issue requiring expert evidence was identified.
5. The application was therefore dismissed. Consequential matters were left for further argument.