Seiko Epson Corporation v Dynamic Cassette International Ltd

Experimental evidence in patent proceedings must be served in accordance with the case-management regime. The court retains a discretion to admit experiments served late, but the governing consideration is fairness. Relevant considerations include whether the opposing party had adequate notice, an opportunity to inspect or witness the experiments, time to test or answer them, and an opportunity to conduct counter-experiments. Where late experiments create a real risk of serious unresolved questions and impose unfair trial preparation, their probative value may not justify admission. The court may refuse them where the same technical issue can be addressed by an available evidential inference.

The claimant alleged infringement of two patents concerning detection of short circuits between terminals on replacement printer ink cartridges. The defendant relied on prior use of the HP10 printer and cartridge system and sought permission to rely on experiments conducted shortly before trial, despite having failed to serve the required notice of experiments in the case-management timetable.

The application concerned whether the experiments should be admitted, whether the defendant should be permitted to reintroduce the document Juve as prior art for an obviousness case, and consequential costs.

1. Experimental evidence. The regime under CPR Part 63 and the relevant practice direction is designed to secure fairness. Experiments undertaken for litigation may be one-sided or incomplete. The opposing party should receive proper notice, an opportunity to inspect or witness the experiments, and a fair opportunity to conduct counter-experiments and answer them. The authorities cited in [2007] EWHC 1204, including Richardson-Vicks Inc.'s Patent and Electrolux Northern Ltd v Black & Decker, supported those principles.
2. The defendant’s notice, exceeding 100 pages and served about eight weeks before a trial due to begin in three weeks, was plainly out of time. The experiments raised serious technical questions, including apparently differing results from terminals which ought to have behaved alike. The claimant’s expert required time for investigation and possible experiments in reply. It would therefore be unfair to require the claimant to deal with the evidence before trial. The experiments were refused despite their potential probative value.
3. The defendant was not deprived of a means of proving how the HP10 system functioned. Both parties had proceeded on the basis that Juve showed how the relevant terminals worked, and no good reason had been identified to reject that inference.
4. Permission was granted to amend the defence to reintroduce Juve for the obviousness case. The defendant was not required to elect between that case and reliance on HP10. The claimant was awarded its costs of the application, with a payment on account of £25,000 within 14 days. Permission to appeal the refusal of the experiments was denied.

First-instance interlocutory decision in the High Court (Patents Court). The judgment records that the proceedings had been case-managed by Norris J, who ordered a staged trial, but no appeal history is stated.