ABSTRACT
The scope of patent protection remains a contentious issue in UK patent law, particularly following the Supreme Court’s landmark decision in Actavis v Eli Lilly. This essay critically evaluates the impact of Actavis on the doctrine of equivalents, which permits infringement claims even when a variant falls outside the literal wording of a patent claim but remains equivalent in substance. The ruling introduced a two-stage test for infringement, marking a departure from purposive interpretation and reshaping UK jurisprudence.
The analysis traces the historical evolution of patent claim construction, from the ‘pith and marrow’ doctrine to Catnic and Kirin-Amgen, highlighting the tension between protecting patentees and ensuring legal certainty for third parties. While the doctrine of equivalents enhances innovation and aligns UK law with the European Patent Convention, it raises concerns about overbroad protection, legal uncertainty, and the ‘possession paradox’. The shift following Actavis has strengthened the rights of patentees but has also made it more challenging to define clear boundaries for patent protection. This broad application of the doctrine of equivalents risks expanding patent scope beyond reasonable limits, creating uncertainty for third parties. To address this, the essay argues for a more precise judicial approach that maintains a fair balance between encouraging innovation and protecting third-party interests while ensuring legal clarity.
Hajnajafi, Amirmohammad, The Doctrine of Equivalents in UK Patent Law After Actavis v Eli Lilly (January 29, 2024).
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