David Parsons v Convatec Limited

A strike-out application should not be used to obtain an unintended preliminary ruling on difficult statutory construction, particularly where the issue is fact-sensitive and the application produces little practical benefit. Questions concerning aggregation of benefits under the Patents Act 1977 were left for trial. A split trial is exceptional and requires a real and substantial advantage over a single trial. The court should undertake a pragmatic balancing exercise, including the clarity of the proposed division, duplication, delay, witness burden, costs, settlement prospects and the overriding objective. Where the proposed division is not clean and risks repeated or unreliable apportionment exercises, the application should be refused.

The claimant, a former employee and named inventor, brought a claim under section 40 of the Patents Act 1977 for compensation in respect of seven patent families alleged to have provided an outstanding benefit to the defendant. At a case management conference, the claimant sought to strike out parts of the defence concerning aggregation of benefits. The defendant sought two trials, beginning with the silverisation patent families. The court determined whether the pleaded aggregation issue should be resolved summarily and whether the proposed division would promote proportionate and efficient resolution of the action.

1. Strike out. The application under CPR r.3.4(2)(a) was refused. The power was discretionary, and the court could defer an issue to trial where doing so furthered the overriding objective. Refusing strike out would not determine that aggregation was impermissible; nor was there a properly constituted preliminary issue before the court.
2. The construction of section 40 should be considered at trial on the facts found. The claimant’s pleaded case covered individual benefits and combinations of patents and inventions. Aggregation was not automatic, and whether it was appropriate depended on the circumstances. Determining the statutory issue in a vacuum risked further satellite litigation and an appeal without materially narrowing the case.
3. Split trial. The defendant’s proposal was rejected. The court applied the pragmatic balancing exercise summarised in Jinxin Inc v Aser Media Pte Ltd and others [2022] EWHC 2431 (Comm). A split trial was a departure from the norm and required a real and substantial advantage, with clear justification.
4. The proposed division was not clean. Revenue from later products overlapped with and cannibalised earlier product lines, so assessment of the first group would require apportionment involving issues reserved for the later trial. The proposal also risked duplicated evidence, strain on witnesses and experts, delay, appeals between trials and greater overall cost. The warnings concerning preliminary and split issues in Bindel v PinkNews Media Group Ltd [2021] EWHC 1868 (QB) and Rosetti Marketing Ltd v Diamond Sofa Company Ltd [2012] EWCA Civ 1021 remained relevant. The split proposal was therefore likely to prolong and increase the cost of the dispute.
5. Other case management matters were resolved, but costs budgeting was adjourned to a later hearing.

First-instance case management decision. The judgment records an earlier decision in the same litigation by Meade J on 1 May 2025, reported as [2025] EWHC 1225 (Pat).