## Facts

- The patentees owned a European patent claiming production of human erythropoietin (EPO) using recombinant DNA methods that introduce an exogenous DNA sequence coding for EPO into a host cell to express the protein.
- A competitor developed “gene activation,” which used human cells’ endogenous EPO gene but placed it under exogenous regulatory control, producing therapeutically equivalent EPO (“GA‑EPO”).
- The patentees alleged GA‑EPO infringed the patent, focusing on claims directed to EPO products and methods (including claims 19 and 26).
- The competitor and an intended UK importer sought declarations of non-infringement and revocation, alleging (among other grounds) lack of novelty/anticipation and insufficiency.
- The trial court held one claim invalid for insufficiency and another valid and infringed; the appellate court held both claims valid but not infringed; cross-appeals followed to the House of Lords.

## Issues

1. How should patent claims be construed under Article 69 EPC, its Protocol, and the Patents Act 1977, including whether protection extends beyond purposive construction through a distinct doctrine of equivalents.
2. Whether GA‑EPO produced by gene activation fell within the properly construed claims (including claims 19 and 26).
3. Whether the challenged claims were invalid for anticipation/lack of novelty and/or insufficiency, including whether the disclosure enabled the full breadth claimed and provided workable boundaries/tests.

## Decision

- The House of Lords dismissed the patentees’ appeal and allowed the competitor/importer’s cross-appeal.
- It held that, on proper construction, the asserted claims did not cover gene activation that avoids introducing an exogenous EPO-coding sequence; therefore there was no infringement.
- It held the patent invalid as claimed and ordered revocation, based on defects including insufficiency and issues of product-claim novelty as pleaded and argued.
- It discouraged reliance on prosecution history for claim construction, favoring construction from the specification and common general knowledge as understood by the skilled person.

## Legal Principles

- Claim construction is objective: the meaning is what the person skilled in the art would understand the patentee to mean from the claim language read in context of the specification and common general knowledge.
- “Purposive construction” rejects strict literalism but does not authorize courts to extend protection beyond what the skilled person would understand the claims to mean; Article 69 EPC and the Protocol require fair protection for patentees while maintaining reasonable certainty for third parties.
- A later-developed technology that achieves the same result does not infringe if it falls outside the technical meaning of the claim language as understood at the priority date.
- Sufficiency reflects the patent bargain: the monopoly is justified only if the specification enables the skilled person to perform the invention across the whole scope claimed and provides workable criteria to determine whether products/processes fall within the claim.
- Prosecution history is generally an unreliable aid to construction because claim meaning should not depend on access to the file and the interpretive value is usually limited.

## Conclusion

The House of Lords construed the EPO patent by purposive, skilled-person interpretation without a free-standing doctrine of equivalents, held that gene activation lay outside the claims as properly understood, and revoked the patent for invalidity where the disclosure and claim breadth did not meet statutory requirements.


Kirin-Amgen, Inc. v. Hoechst Marion Roussel Ltd., [2004] UKHL 46 (H.L.)