Thursday, March 15, 2012

The Problem-Solution Approach in the Claim Construction Context

Wenzel Downhole Tools Ltd v National-Oilwell Canada Ltd 2011 FC 1323, 98 CPR(4th) 155, Snider J

I am a bit of a fan of the EPO problem-and-solution approach to obviousness, as I feel it is a structured method of defining the inventive concept, and while it is not formally part of Canadian law, there are many cases which invoke similar language in the obviousness context: see here. Snider J’s approach to claim construction in Wenzel is interesting, first because she expressly equates the essential elements of the claim with the inventive elements of the invention, and secondly because she in effect invokes the problem-and-solution approach as part of the claim construction process.

Snider J’s claim construction analysis begins with the usual boilerplate from Whirlpool 2000 SCC 67 and Free World 2000 SCC 66, including the need to identify the essential elements of the claim. As is now normal, she does not cite the Improver questions endorsed by the SCC in Free World at [55]-[56] (but see here for a recent decision that does). Instead, Snider J expressly equates the essential elements with the inventive elements:

[39] In very succinct terms, an essential element is one that, if it were changed, would affect how the invention works.

Subsequently, in considering the claims in issue, Snider J contrasts “[t]he ‘inventive’ or essential components,” with those elements which are “simply references to the state of the art that existed at the time of [the] invention” [76]. My own view is that this approach, which equates the inventive components withe essential elements, is fundamentally correct. I have argued that “a purposive analysis of the Patent Act implies that the presumed intention of the patentee in drafting, and of the Crown in granting the patent, is to claim the full patentable extent of the invention disclosed,” and for that reason the inventive elements should be presumed to be essential (The Essential Elements Doctrine in Patent Infringement, (2011) 22 IPJ 223, draft version here).

If the inventive concept is important to a purposive construction, how is it to be identified? Snider continues her claim construction by saying:

[61] To give a purposive construction to the claims of a patent, it seems to me that one should understand the purpose of the invention and the problem that the invention sought to address. For the most part, inventors come to their patentable inventions in order to solve a problem. What was the problem that the ‘630 Patent was intended to address?

[63] In his invention summary, Bill Wenzel indicates that his invention offers a “method of increasing the off bottom load capacity of a bearing assembly without increasing the length of the tool”. In sum, this then was the “problem” that was solved by the ‘630 Patent.

This in effect uses problem-and-solution approach to identify the inventive concept, but in the context of claim construction instead of obviousness. This is entirely logical if one accepts that identification of the inventive element is a key to a purposive construction.

In summary then, Snider J’s essential elements analysis boils down to saying:

(1) the essential elements are the inventive elements;
(2) the inventive elements are identified using the problem-and-solution approach.

In my view, both of these points are fundamentally sound and helpful. It is possible to quibble a bit; for example, even if one presumes that the inventor intended to claim the inventive elements that have been disclosed, it may be that in some cases the text or context of the claims rebut that presumption. This is essentially the refinement that the Improver “mangle” aimed to address. (Snider J did say the equating essential elements with inventive elements was a "very succinct" description of the analysis.) And in any event, the decision in Wenzel did not turn on identification of the essential elements, so Snider J’s analysis is suggestive rather than strong precedent. But even though it is only suggestive, I would call it a very welcome suggestion.

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