Introduction

The case of Sandoz Ltd v Bristol-Myers Squibb Holdings Ireland Unlimited Company ([2023] EWCA Civ 472) addressed a fundamental aspect of patent law: the concept of plausibility in determining the validity of a patent. This case marked a significant examination in the England and Wales Court of Appeal (Civil Division) regarding the necessity of plausible claims within patent specifications, particularly when the claim pertains to a single chemical compound.

The dispute centered around European Patent (UK) No. 1 427 415, which claimed the compound apixaban as a factor Xa inhibitor used in treating thromboembolic disorders. The Claimants, Sandoz and Teva, challenged the patent's validity on the grounds that the specification did not make it plausible that apixaban possessed the claimed inhibitory activity, thereby rendering the patent invalid under Articles 56 (Inventive Step) and 83 (Sufficiency) of the European Patent Convention (EPC).

Summary of the Judgment

The Court of Appeal upheld the lower court's decision declaring the patent invalid. The core reasoning was that the patent application failed to make it plausible that apixaban was an effective factor Xa inhibitor at the nanomolar Ki range, which is essential for therapeutic utility. The absence of empirical data or a solid theoretical foundation within the application led the court to conclude that the invention did not fulfill the necessary technical contribution to justify the patent's monopoly.

BMS, the patent proprietor, appealed the decision, arguing that the judge erred in applying the standard of plausibility. However, the Court of Appeal maintained that the judge correctly applied existing legal principles, particularly those established in the Warner-Lambert case, emphasizing that mere assertions or structural reasoning without supportive data do not meet the plausibility requirement.

Analysis

Precedents Cited

The judgment extensively referenced key precedents that have shaped the interpretation of plausibility in patent law:

• Agrevo/Triazoles (T 939/92): Established that the technical contribution must justify the patent's scope.
• Johns Hopkins (T 609/02): Highlighted the necessity of plausible technical effects derived from the application.
• Warner-Lambert Co LLC v Generics (UK) Ltd [2018] UKSC 56: Reinforced that a patent cannot claim an effect without adequate support in the specification.
• G 2/21: Clarified the role of post-published evidence in establishing technical effects.

These cases collectively underscore that plausibility is not a standalone condition but is intrinsically linked to whether the patent's technical teaching justifies its claims.

Legal Reasoning

The Court of Appeal delved into the legal framework governing patent validity under the EPC, particularly Articles 52, 56, 83, and 138. It emphasized that although the EPC does not explicitly mention plausibility, this concept has been implicitly embedded through extensive case law to ensure that the scope of patent protection aligns with the technical contribution made.

Key points in the court's reasoning include:

• Technical Contribution Must Justify Monopoly: The scope of patent claims must correspond to the technical advancement provided by the patent.
• Plausibility Based on Specification: The application must, inherently, make it plausible that the invention solves the stated technical problem.
• Role of Empirical Data: For chemical compounds, especially single entities like apixaban, empirical data supporting the claimed technical effect is crucial.
• Post-Published Evidence Limitations: Such evidence cannot replace the need for plausibility established at the filing date.

The court found that the patent lacked sufficient evidence within the specification to make the effectiveness of apixaban plausible. Assertions without supportive data or theoretical underpinnings were deemed speculative and insufficient.

Impact

This judgment reinforces the stringent requirements for patent validity concerning plausibility, especially for chemical compounds with broad claims. Future patent applications will need to ensure that their specifications provide credible support for any asserted technical effects. This case serves as a cautionary tale for patentees to back their claims with robust data or well-founded theoretical explanations to avoid invalidation on the grounds of lacking plausibility.

Additionally, the decision aligns national UK patent law more closely with EPO standards, promoting consistency in how plausibility is assessed across jurisdictions within the EPC framework.

Complex Concepts Simplified

Conclusion

The Sandoz Ltd v BMS judgment underscores the critical role of plausibility in patent validity, particularly for chemical compounds. Patentees must ensure that their specifications not only describe the invention but also provide credible evidence or reasoning to support any claimed technical effects. This case sets a precedent that mere structural descriptions or future testing possibilities are insufficient. The technical contribution must be evident and justified within the original patent application to sustain the scope of the patent claims.

Consequently, this decision enhances the robustness of the patent system by ensuring that patent grants are matched by tangible technical advancements, thereby preventing speculative or overstated claims from receiving undue protection.