Everseal Stationery Products Ltd v Document Management Solutions Ltd & Ors

A patent claim requiring an adhesive to self-seal irreversibly is assessed by asking whether, after limited attempts to disguise unauthorised opening, the recipient can detect tampering from both the adhesive structure and the base material. Fibre tear is sufficient but not essential; visible deformation may suffice. For prior-use anticipation, proved primary facts may establish a feature on the balance of probabilities, but an inference from those facts must be inevitable, not merely likely. A patent lacked novelty where prior use established the claimed features, and lacked inventive step where the skilled team would have been led to use known adhesives without a relevant technical prejudice.

Everseal, proprietor of a patent for business forms or mailers using a dry, non-tacky contact adhesive, alleged that three mailers manufactured or sold by Document Management Solutions Ltd infringed claims 1 and 7. DMSL counterclaimed for revocation on grounds of lack of novelty, lack of inventive step and added matter. Everseal also faced arguments under section 62(3) of the Patents Act 1977 concerning damages or an account of profits.

The court considered the construction of irreversibility, infringement by the three mailers, prior use of the Viking Mailer, two US patents, inventive step and procedural economy in relation to added matter and good faith.

1. Construction. Applying the approach in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46, as explained in Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd [2009] EWCA Civ 1062, an irreversible seal required the recipient to be able to detect earlier opening from both the adhesive structure and the base material. Fibre tear was sufficient but not necessary. Visible deformation could suffice if it made tampering evident. The assessment assumed that an unauthorised opener had made limited efforts to disguise the opening.
2. Infringement. Mailer 1 fell within claim 1, because its anti-tamper slits caused the necessary disruption in the base material. Infringement of claim 7 was not proved. The experiments concerning Mailers 2 and 3 did not establish the necessary deformation after smoothing or other limited attempts to restore their unopened appearance. Neither therefore infringed the relevant claims on the evidence.
3. Novelty. Following Kavanagh Balloons Pty Ltd v Cameron Balloons Ltd [2004] RPC 5, the overall assessment of alleged prior use was on the balance of probabilities. However, where a claimed feature was inferred from proved primary facts, anticipation required the inference to be inevitable. The Viking Mailer was proved to have been a dry contact-adhesive mailer that self-sealed under finger pressure and tore when opened. Claim 1 therefore lacked novelty. The evidence that its adhesive was probably natural rubber latex stabilised with ammonia was insufficient to establish lack of novelty for claim 7.
4. Inventive step. The skilled team would have known of adhesives capable of satisfying the claimed pressure and irreversibility requirements. No relevant technical prejudice deterred their use in ordinary mailers, and adapting known adhesives for laser-printable mailers was a routine task. Claims 1 and 7 therefore lacked inventive step over the cited prior art.
5. Other issues and result. The court declined to determine added matter, applying the procedural economy approach in Teva UK Limited v Leo Pharma A/S [2014] EWHC 3096 (Pat). The good-faith arguments under section 62(3)(b) and (c) of the Patents Act 1977 did not arise on the findings. The Patent was invalid.