Summary of Opinion (Anonymised)
Factual and Procedural Background
This is an appeal arising from patent litigation between Company A (Appellant) and Company B (Appellee) concerning continuous glucose monitoring (CGM) technology. Company A alleged infringement by Company B of two patents: EP 627 (user interface aspects) and EP 223 (validation of safety-critical software on uncontrolled devices). Company B counterclaimed that two Company A products infringed its patents and both parties counterclaimed for revocation. A six-day trial was held before Judge Mellor in Nov–Dec 2022. In a judgment delivered 15 January 2024 the trial judge held all four patents invalid; a consequential order was made 13 January 2025. Company A obtained permission to appeal the revocation of EP 627 and EP 223 (permission granted by Judge Arnold on 25 March 2025). The overall dispute has settled and Company B did not oppose the appeal; The Comptroller was invited to assist the Court pursuant to practice directions.
Legal Issues Presented
- Whether EP 627 lacks novelty in light of the STS Guide (prior public user guide).
- Whether EP 223 lacks novelty in light of Gejdos (US patent application) on grounds that it discloses: (a) a safety-critical application; (b) installation and functional checks; and (c) selective enablement.
- Related procedural/legal issue: the proper role of expert evidence in determining implicit disclosure for novelty (as distinct from inventive step).
Arguments of the Parties
Appellant's Arguments (Company A)
- EP 627: (ground 1(b)) the three-day sensor expiry session/countdown in the STS Guide is not a "predetermined routine" because it merely measures time and is not capable of interruption; (ground 1(a)) the two notifications in the STS Guide (30-minute and 0-hour) do not relate to the same predefined alarm condition.
- EP 223: (ground 1) Gejdos does not disclose a "safety critical application" as claimed; (ground 2) the database integrity check is not an installation or functional check as required by the claim and a single check cannot satisfy both requirements; (ground 3) Gejdos does not disclose "selective enablement" (disabling safety-critical features while enabling non-safety-critical features).
Comptroller's Arguments
- EP 627: emphasised the broad language of the claim and cautioned against reading limitations from examples into the claim; the countdown mechanism interacts with the user interface and can be read as the predetermined routine.
- EP 223: submitted that (a) Gejdos could be a safety-critical application given the risk of detriment from inaccuracies; (b) nothing in the claim precludes a single check serving as both installation and functional check; and (c) expert evidence can assist the court in construing a prior document for implicit disclosure.
Expert Evidence
- Company B relied on Expert Stirbu, who gave evidence that paragraph [0043] of Gejdos (error message on failed integrity check) would be understood by the skilled person to include disabling database-related (safety-critical) functions, i.e. selective enablement. That passage was not cross-examined.
- Company A's expert (Expert Palerm) gave contrary evidence, which the judgment records.
Table of Precedents Cited
| Precedent |
Rule or Principle Cited For |
Application by the Court |
| Actavis v Eli Lilly [2017] UKSC 48 |
Modern approach to patent construction (Protocol; skilled person perspective; compromise between literal/liberal). |
Used to frame claim construction approach: purposive, contextual, skilled person with common general knowledge. |
| Saab Seaeye v Atlas Elektronik [2017] EWCA Civ 2175 |
Detailed overview of patent construction principles post-Actavis. |
Relied on for the list of construction principles to be applied. |
| Virgin Atlantic v Premium Aircraft [2010] RPC 8 |
Earlier elaboration of construction principles (Jacob LJ). |
Referenced as part of the construction methodology. |
| Nokia v IPCom [2009] EWHC 3482 |
Warning against reading limitations into general claim language. |
Comptroller invoked it to argue against artificially restricting claim language; Court acknowledged principle but found claim required a particular reading. |
| Fisher and Paykel Healthcare Ltd v Flexicare Medical Ltd [2020] EWHC 3282 |
Warning against expanding specific exhaustive language beyond its scope. |
Used to support principle that construction must match how skilled person would understand the author’s intention. |
| Synthon BV v SmithKline Beecham plc [2005] UKHL 59 [2006] RPC 10 |
Anticipation requires prior art to provide clear and unmistakeable disclosure and enablement (two-part test). |
Applied to frame novelty analysis: disclosure (including implicit disclosure) and enablement (enablement not in issue here). |
| General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1971] FSR 417 |
Metaphor of prior document 'planting the flag' (anticipation). |
Quoted in discussion of what constitutes anticipation. |
| ModernaTX Inc v Pfizer Ltd and ors [2025] EWCA Civ 1030 |
Implicit disclosure is strict: the prior art must necessarily imply the invention; mere possibility/obviousness is insufficient for novelty. |
Applied to reject reliance on expert evidence that appeared to show obviousness rather than necessary implication (EP 223 ground 3). |
| Technip France SA's Patent [2004] EWCA Civ 381 |
Court must 'don the mantle' of the skilled person when construing documents. |
Referred to when explaining the role of expert evidence in instructing the court on common general knowledge. |
| FAGE UK Ltd v Chobani UK Ltd [2014] EWCA Civ 5 |
Appellate deference: appellate court will defer to trial judge's findings absent clear error. |
Applied as governing standard of review, with note that delay in judgment warrants careful review. |
| Byers v Saudi National Bank [2022] EWCA Civ 43 |
Applied standard of deference to findings of fact and evaluative determinations on appeal. |
Invoked to explain appellate review standard. |
Court's Reasoning and Analysis
Author of the opinion: Judge Birss. The Court applied established patent construction principles: purposive, contextual construction from the perspective of the skilled person, avoiding importing unwarranted limitations but also giving effect to claim language as a whole.
EP 627 (STS Guide)
The trial judge had found the STS Guide anticipated EP 627. On appeal the Court analysed whether the STS countdown/session qualified as the claimed "predetermined routine" and whether the two notifications related to the same "predefined alarm condition".
On the first point (ground 1(b)) the Court held that a skilled reader would understand the claimed indications to be caused by something distinct from the predetermined routine such that they could meaningfully interrupt it (or be contemplated as interrupting it). The countdown routine in the STS Guide was a singular process with embedded alerts and did not fit that purposive reading; treating the alerts as both the routine's own processes and as the separate indications created circularity and rendered claim features surplusage (integer 1.9). The Court therefore concluded the countdown was not the claimed predetermined routine and allowed the appeal on ground 1(b).
On the second point (ground 1(a)) the Court held that the 30-minute notification (warning of remaining time) and the 0-hour notification (reporting actual expiry) are distinct conditions. The claim requires a single detected predefined alarm condition; the STS Guide's two notifications do not relate to the same condition in the sense required by the claim. The appeal on ground 1(a) was therefore allowed.
EP 223 (Gejdos)
The trial judge had found Gejdos anticipated EP 223 on three bases; the appeal raised three corresponding grounds.
Ground 1 — safety-critical application: The Court accepted the trial judge's reasoning that the definition of "safety critical application" in EP 223 is broad (failures "may result in" significant detriment) and does not require the failure to directly cause harm. A healthcare database like Gejdos falls within that broad definition because inaccuracies could result in significant detriment. The appeal on ground 1 was refused.
Ground 2 — installation and functional checks: The Court upheld the trial judge's finding that Gejdos's database integrity check could serve as both an installation and a functional check for the purposes of the claim. The claim's language did not require directness or exhaustive checking of every component; a check that would fail if installation/functionality had failed suffices. The appeal on ground 2 was refused.
Ground 3 — selective enablement: The Court accepted that Gejdos does not explicitly disclose selective enablement. The trial judge relied on Expert Stirbu's unchallenged evidence that a skilled person would understand paragraph [0043] of Gejdos to include disabling database-related functions. The appellate Court held that such expert opinion was insufficient to establish the necessary strict implicit disclosure for anticipation: the expert evidence appeared to be more consistent with obviousness rather than a necessary implication, and there was no cross-examination or other evidence showing the proposition was necessarily implicit. For novelty by implicit disclosure the invention must necessarily follow; that was not demonstrated. The appeal on ground 3 was allowed.
Holding and Implications
HOLDING: The Court allowed the appeal in respect of EP 627 grounds 1(a) and 1(b) and EP 223 ground 3; the Court dismissed the appeal in respect of EP 223 grounds 1 and 2. (As stated in the opinion: the appeals in respect of grounds 1 and 2 relating to EP 223 are dismissed; the appeals in respect of ground 3 relating to EP 223 and grounds 1(a) and 1(b) relating to EP 627 are allowed.)
Implications: The decision reverses the trial judge's novelty-based invalidity findings to the extent indicated above (EP 627 and EP 223 ground 3). The Court emphasised that implicit anticipation is a strict test requiring that the prior art necessarily and unambiguously disclose the claimed subject-matter; expert evidence that indicates what would be obvious to a skilled person cannot substitute for such necessity. No broader novel legal principle was established beyond the application of existing authorities on construction, anticipation and the limited role of expert evidence for implicit disclosure.
Bench: Judges Birss (author), Judge Stuart-Smith and Judge Miles.