DBE Energy Ltd v Biogas Products Ltd

In a shorter trial, expert evidence must remain within the real issues defined by the statements of case and their context. A general allegation putting a claimant to proof on causation, mitigation or loss does not permit a party to introduce materially new theories through expert evidence. Unpleaded criticisms of project management, alternative remedial schemes, or the necessity for the equipment are inadmissible where they would require substantial further evidence. Evidence concerning a pleaded hydraulic-separation proposal was permitted, but only for its pleaded and limited purpose: reducing commissioning delay and consequential loss. Background technical observations could remain where they were not advanced as a new cause of failure or loss.

The claimant alleged that the defendant had negligently or contractually defectively designed and supplied components for an anaerobic digester system. The components failed under water pressure, and the claimant sought replacement costs and lost profits.

The claimant objected to categories of expert evidence in the defendant’s mechanical engineer’s report. The objections concerned new remedial schemes, the alleged sufficiency of one pasteurisation tank, the necessity of heater jackets, criticism of project management, and technical matters said to affect pressure, causation or mitigation.

1. Scope of expert evidence. In a shorter trial, the court must ensure that expert evidence serves the proportionate and speedy resolution of the pleaded dispute. Lists of issues and issues for experts must be read in the context of the statements of case. They do not give a party or its expert carte blanche to introduce previously unseen arguments on causation, including mitigation of loss.
2. Unpleaded theories excluded. Proposed remedial schemes in paragraphs 6.22–6.25 of the report were not properly raised before service of the report and were excluded. The general suggestion that only one tank was ever needed, and the contention that heater jackets were unnecessary or required only exceptionally, were likewise outside the pleaded case and inadmissible.
3. Hydraulic separation permitted in a limited form. The defendant could rely on hydraulic separation for the second pasteurisation tank as a temporary measure enabling commissioning to proceed sooner and potentially reducing the lost-revenue claim. It could not use the point to argue generally that only one tank was required or that two replacement tanks were unnecessary.
4. Expert competence and relevance. A mechanical engineer was not accepted as an expert on general project management. The broad criticism of the claimant’s management system did not arise from the pleaded design-responsibility issue and could not support a substantial new mitigation or contributory-negligence case. Limited factual observations drawn from documents were not objectionable.
5. Background matters. Paragraphs 5.9 and 5.17 could remain as background. The defendant had to clarify whether either matter was relied upon as causing the component failures or any loss. If so, the claimant could respond; otherwise the matters would go no further.

Not stated in the judgment.