Purposive Construction When the Inventor Is Mistaken as to the Inventive Contribution

ABB Technology AG v Hyundai Heavy Industries Co Ltd 2013 FC 947 Barnes J
            2,570,772 – 2,567,781

ABB Technology, in which both patents at issue were held to be invalid and not infringed, is a fairly straightforward case which turned largely on its facts. It does, however, illustrate an interesting point regarding purposive interpretation of the claims.

The Supreme Court has said that “where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction” Western Electric Co [1934] SCR 570 at 574, quoted by the SCC inter alia in quoted by the SCC in Consolboard, supra note 58 at 521, in Whirlpool 2000 SCC 67 [49(g)[, and Free World, 2000 SCC 66 at [43]; and see Schmeiser, 2004 SCC 34, at [35] referring to this as “the guiding principle” of claim construction. In my article on “The Essential Elements Doctrine” (2011) 22 IPJ 223 (draft available here), I explained this as following from purposive construction. The disclosure is the quit pro quo for which the patent is granted, and the inventor will normally want to claim the full scope of the invention disclosed, in order to maximize the value of the patent, but not more, in order to avoid invalidity. So, as I argued in my article, a purposive analysis of the Patent Act implies that the presumed intention of the patentee should be to claim the full patentable extent of the invention disclosed. In my article I discussed problems which arise when the textual and purposive analyses conflict. ABB Technologies raises a common problem which I did not address: what happens when the inventor has misunderstood the nature of their contribution?

The invention at issue relates to gas-insulated switchgear (GIS) assemblies, which are used in electrical power transmission. A major problem related to switchgear assemblies is the possibility of explosion caused by electrical arcing between two components of the switchgear. A circuit breaker is the main safety mechanism to deal with this problem. If maintenance of the circuit breaker is required, it must be disconnected from the circuit by grounding it. In North American practice this is done using a separate grounding switch. When maintenance is undertaken, it is important to verify the position of the grounding switch to ensure that the breaker really is grounded. This may be difficult because the grounding switch is located inside the assembly. The 781 patent solved this problem by providing a window which allows visual inspection of the switch position.

The key claim (Claim 1), claimed the use of viewing windows to ascertain the positions of the switches described in the claim as “a moveable switch-contact element” [35]. The construction of this term was a crucial issue, because the patentee, ABB, acknowledged that the prior art disclosed the use of viewing windows to observe the position of knife blade switches [37]. ABB argued that the term should be construed to encompass only sliding contact switches [37], saying that “the purposive approach requires the Court to choose an available construction that favours the validity of these patents” [27].

Barnes J rejected this, saying that “Forming a 'reasonable view' of patent language does not, to my thinking, prefer any arguable interpretation that would uphold the patent. In most cases the language of the patent, when viewed contextually and objectively, will be sufficient to establish what was intended thereby ensuring the attainment of its purpose. I would add that the purposive approach is not an invitation to the Court to ignore the ordinary rules of grammar and syntax” [29]. I agree with this statement, but how is it to be reconciled with the principle that “where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction”? In this case, what the inventor had “actually invented” (if anything – the invention was also held to be obvious, but that is a separate issue), was a window for viewing sliding contact switches. Why should the court not endeavour to construe the claim accordingly? The straightforward answer is that in this case the language of the specification cannot be read to be limited only to sliding contact switches. Purpose, text and context must be considered together in construing the claims, and when there is a tension between purpose and text, the text, if sufficiently clear, will prevail: see Canada Trustco 2005 SCC 54, [10]. This is essentially how Barnes J analyzed the claim: see generally [44]-[47].

While this is an entirely sound approach, I would suggest that in this case there is in any event no real conflict between a purposive and textual approach. A purposive approach to construction asks us to consider the drafter’s intent. In drafting the patent, the inventor’s purpose will be to claim the full extent of what they have invented; but more precisely, it will be to claim the full extent of what they believe they have invented, not what they may actually have invented. If the inventor of the 781 patent was unaware of the use of windows to visualize knife switches, so that he believed he had actually invented the use of windows to visualize all kinds of switches, then he would naturally intend to claim windows for visualizing all switches. Consequently, the text reflects the purpose – to claim all switches.

How do we tell what the inventor believed they had invented? The answer is to look to the specification: see eg [42], where Barnes J points out that nothing in the specification suggests a distinction between knife and sliding contact switches. This is not circular. The applicable principle, I suggest, is that the inventor should be presumed to claim the invention that they have disclosed. If the inventor has properly understood their true contribution, and fully disclosed it in the specification, then even if the claim language is ambiguous, the courts should strive to interpret the claims in a way that protects that invention, on the view that the inventor must have intended to claim it. But purposive interpretation does not support a principle that the construction should favour validity, because an inventor who did not understand their true contribution might not have intended to claim a valid invention.