The Essential Elements Doctrine in Patent Infringement: Free World and Whirlpool in Light of Kirin-Amgen
Intellectual Property Journal, Vol. 22, p. 223, 2011
35 Pages Posted: 20 Mar 2011
Date Written: March 19, 2011
A decade ago in Whirlpool Corp. v. Camco Inc. and Free World Trust v. Électro Santé Inc. the Supreme Court of Canada endorsed a purposive approach to the construction of patent claims in which a “key” is identification of the essential elements of the claim. The Court endorsed the essential elements test set out by Hoffmann J. in Improver Corp. v. Remington Consumer Products Ltd.. Despite this endorsement, the Improver questions are rarely used in Canada, while in the UK Lord Hoffmann has not only repudiated his own approach as an unnecessary “mangle,” he has indicated that the essential elements doctrine itself is unnecessary since the adoption of purposive construction. Should Canada follow the UK and abandon the Improver questions and the essentiality doctrine? This article addresses these questions by providing a three-stage structured framework for claim construction based on general principles of statutory construction. I use this framework to argue that Lord Hoffmann’s critique of the essential elements doctrine is misplaced, and that while the Improver questions are a mangle, they should be clarified and revised, not repudiated. The essentiality doctrine is unnecessary in most cases, but it is the key to hard cases. It should be used less often, but more carefully.
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