Mather v Ministry of Defence

A preliminary issue should be ordered only with caution. The proposed issue must be precisely formulated and ordinarily concern a decisive question of law capable of determination on agreed or assumed facts without significant delay, duplication or unfairness.

Where causation involves disputed scientific and factual matters, overlaps with breach of duty or limitation, and may generate an interlocutory appeal, separating it may increase cost and delay rather than achieve the overriding objective. In such circumstances, the court should ordinarily determine related liability issues together on the actual evidence. A preliminary issue may be revisited if circumstances materially change.

The claimant brought a personal injury claim against his former employer, alleging that occupational exposure to organic solvents caused multiple sclerosis and psychiatric injury. The defendant denied liability, causation and damage, and relied also on limitation.

The defendant sought an order that causation be tried as a preliminary issue, either on assumed exposure facts or as the first stage of a trial. The claimant opposed that course, contending that exposure, medical causation, breach of duty and other liability issues overlapped and could not safely be separated. The court also considered the claimant’s application to rely on an addendum expert report.

1. The application for a preliminary trial of causation was refused. The court has power to direct a separate trial under CPR Part 3.1(2)(i), but that discretion is subject to the overriding objective in CPR 1.1(2) and CPR 1.2(a).
2. The guidance identified in McLoughlin v Grovers (A Firm) [2001] EWCA Civ 1743; [2002] QB 1312 was applied. A preliminary issue should normally be decisive or potentially decisive, usually a question of law, triable on agreed or assumed facts, capable of determination without significant delay including the consequences of an appeal, and directed through proper case management. The issue must also be formulated with precision and care, as stated in Lahey v Pirelli Tyres Ltd [2007] EWCA Civ 91.
3. Causation in this claim was not a sufficiently crisp issue. It involved complex questions of law, science and fact, including the divisibility of multiple sclerosis and psychiatric injury, the relevance of exposure after 1994 and 2000, the applicable causation test, and the possible relevance of the evidence of factual and occupational-hygiene witnesses.
4. The assumed facts proposed by the defendant risked excluding relevant evidence and separating matters that substantially overlapped. A finding on causation could require later reconsideration after findings on breach of duty, and different judges or stages could produce inconsistent assessments of the evidence. A preliminary ruling could also cause substantial delay and additional costs if appealed.
5. Absent an application for strike out or summary judgment, it was premature to assume that the claimant’s case would fail or that the legal issues were immaterial. The court considered it more prudent to resolve the issues on actual rather than assumed or hypothetical facts, consistent with the guidance discussed in Barrett v Enfield London Borough [2001] 2 AC 550 and Vedanta Resources PLC v Lungowe [2019] UKSC 20.
6. The defendant’s reliance on Saunderson v Sonae Industria (UK) Ltd [2015] EWHC 2264 (QB) did not assist at this interim stage. That case concerned criticism of a claimant’s conduct after a lengthy trial and had no application here.
7. Permission was granted for the claimant to rely on Professor Cherrie’s report dated 10 February 2021. The experts were directed to discuss specified matters and, if necessary, produce a revised joint statement. Costs were reserved, with a preliminary view that the costs should be costs in the case.

This was a first-instance case-management decision. On 20 November 2020, Master Thornett released the defendant’s application to be heard by a Queen’s Bench Division judge exercising wider case-management powers. The application was refused by the High Court.