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  • Peter Kam Fai Cheung SBS

The Doctrine of Equivalents


In the context of patent infringement, there is the doctrine of equivalents which is premised on language's inability to capture the essence of inventive innovation. Judicial support of the doctrine would create some uncertainty. The UK Supreme Court decision of Actavis v Eli Lily [2017} UKSC 48, gives due account of any element which is equivalent to an element specified in the patent claims.

Direct infringement is established if a relevant item infringes any of the patent claims as a matter of normal interpretation (ie the claims are interpreted with their description and drawings). Direct patent infringement is also established if a relevant item, though characterized as a variant, only varies from the patented invention in an immaterial way (ie the doctrine of equivalents). Although sections 73-74 of the Hong Kong Patents Ordinance Cap 514 stipulate the prevention of direct and indirect use of inventions, the legal issue here is whether a party is liable even though the alleged infringing stuff do not fall within the literal scope of a patent claim.

The UK Supreme Court reformulates the test of materiality or equivalents as: (1) despite the claims' literal meaning, the variant achieves substantially the same result in substantially the same way ie the inventive concept has been revealed; (2) it is obvious to a person skilled in the art, reading the patent at the priority date, knows the variant achieves substantively the same result in substantially the same way; and (3) the person skilled in the art would not conclude the patentee would intend strict compliance of the literal meaning of the claims. As a result, the UK doctrine of equivalents is alive in 2017. The hallmark case would become a persuasive authority of Hong Kong law in determining the extent of patent protection.

I take an active interest in the doctrine of equivalents from the comparative legal analysis perspective. Its rationale has recently inspired me to argue in a different context about two sets of facts that can achieve substantively the same result in substantially the same way. Whether my arguments are persuasive enough would also depend on how liberal or smart are those in authority!

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