Safestand Limited v Weston Homes PLC & Ors

Permission to amend a pleaded case on the first day of trial is exceptional. The applicant must show a real prospect of success, provide a satisfactory explanation for delay, and establish why the balance of justice requires amendment despite disruption, wasted costs, delay and the public interest in efficient litigation.

For patent construction, a builders’ trestle is a self-supporting metal stand incorporating one or more beams on which a working platform may be laid. Compliance with additional stability requirements in a British Standard is not part of that definition. Cross-braces do not prevent component stands from being trestles, and extra features do not avoid infringement where all claim integers are present.

For registered designs, the registration must identify a single design with reasonable certainty. Alternative embodiments, including alternative colours or optional components, may invalidate the registration.

Safestand alleged infringement of three patents and three re-registered designs concerning builders’ trestles. Weston denied infringement and counterclaimed for revocation of two patents for lack of inventive step and invalidity of the designs for lack of unity, clarity and individual character.

At the start of trial Weston sought permission to amend its invalidity case to plead prior use based on a recently located newspaper article. The application raised the principles governing very late amendments.

The court also had to construe the patents, assess infringement and inventive step over cited prior art, and determine whether the registered designs depicted single, sufficiently clear designs.

1. Late amendment. The application to plead prior use was dismissed. Although the proposed case had a real prospect of success, Weston gave no satisfactory explanation for why the newspaper article had not been found and pleaded earlier. A second trial would still cause wasted costs, delay and unnecessary court time. The overriding objective therefore required refusal.

2. Patent construction and infringement. The skilled person would understand “trestle” in accordance with the definition in British Standard 1139-4: a self-supporting metal stand incorporating one or more beams on which a working platform may be laid. The definition was not supplemented by the Standard’s separate stability and load-bearing requirements, or by an imprecise requirement that the structure not be too wobbly. Cross-braces could add stability without preventing the individual stands from being trestles. A system containing all the claim integers remained within the claim even if it also had cross-braces.

3. The “supported in use” requirement was assessed when the system performed its intended function, including the way it was actually used. The KK1500 and KK600 systems satisfied that requirement, and the telescopic rails supplied variable spacing between attachment points. UK 978 and EP 738 were therefore infringed. UK 822 was also conceded to be infringed.

4. Inventive step. The fourth stage of the Pozzoli analysis is a single undivided stage. The skilled person must consider cited prior art diligently and ask whether, without knowledge of the invention, they would contemplate a variation falling within the claim. It is impermissible to introduce a preliminary assessment of whether the prior art is an attractive starting point, since that risks assuming knowledge of the invention. EP 738 and UK 822 were not shown to lack inventive step over the cited prior art.

5. Registered designs. The RRDs were invalid. Their images disclosed alternative embodiments, including alternative colours and optional components, rather than one clearly identifiable design. The court could admit limited expert assistance where specialised knowledge helped interpret registration images, although objective interpretation remained primarily a judicial task. None of the RRDs was therefore infringed.

6. Permission was granted to amend UK 978. The conditional amendment of EP 738 did not arise because the patent was valid as granted. Judgment was entered for Safestand on the patent claims and for Weston on the validity of the RRDs.