Nailed It – the Full Federal Court upholds purposive construction of fuel cell claims

A central tenet of patent interpretation under Australian law is that the specification should be a given a purposive construction rather than a purely literal one.  While this is different to the Doctrine of Equivalents that exists in other jurisdictions, a purposive construction can result in a claim defining an invention being interpreted in a way that extends its scope beyond the literal meaning of the words employed at drafting.

Handing down the first Australian intellectual property judgment of 2023, the Full Federal Court in Airco Fasteners Pty Ltd v Illinois Tool Works Inc [2023] FCAFC 7 has dismissed Airco Fasteners Pty Ltd’s (Airco’s) appeal and affirmed the purposive claim construction of primary judge Justice Rofe.

Key takeaways

The Full Court confirmed that:

• The Court can take into account appropriate, functional considerations when construing the specification in the context of constructing a claim
• Dependant claims can be used to assist in the construction of independent claims
• Key words repeated throughout a patent specification can be interpreted sensitive to context
• The Court must determine the construction of patent claims, aided by expert evidence, however that opinion evidence does not supplant the Court’s role

Background

The Illinois Tool Works Inc (Illinois) patent in question related to an in-can fuel cell metering valve, primarily used in combustion tools such as nail guns. The invention includes “an internally mounted metering valve arranged such that a measured dose of fuel is dispensed each time the stem is pressed into the “open” position”.^[1]

Illinois brought patent infringement proceedings against Airco who were importing, supplying and selling combustion tool fuel cells in Australia.

At first instance, Justice Rofe undertook an extensive construction analysis of the claims, and held that Airco’s combustion tool fuel cells had infringed Illinois’ patent.^[2]

Airco’s Appeal

Airco appealed to the Full Federal Court arguing that Justice Rofe erred in her construction of Illinois’ patent claims. The two primary issues before the Court were whether the Airco products had, as her Honour found:

• “a fuel metering chamber disposed in close proximity to said closure” (close proximity integer); and
• “a valve body having a second end opposite said fuel metering chamber located within said container” (second end opposite integer).^[3]

Concerning the close proximity integer, Airco argued that her Honour’s construction failed to give effect to the natural meaning of “close proximity” as emphasising the requirement of closeness, rather than simply proximity. Airco submitted that this was contrary to the expert evidence.^[4]  Further, Airco argued that because claim 1 mandated that the fuel metering chamber was within the valve body, a fuel metering chamber located in that part of the body furthest from the closure could not be characterised as being in “close proximity” to the closure.

Airco submitted that the second end opposite integer ought to have been construed to require the fuel metering chamber be located at the other (ie “opposite”) end of the valve body to the “second end” of the valve body and outside (not “within”) the fuel container. The appellant also argued that the construction adopted by the primary judge involved construing the word “opposite” to have different meanings in the same document.

The Full Court Decision

Justices Rares, Moshinsky and Burley unanimously dismissed the appeal and upheld the decision of Justice Rofe.

The Full Court agreed that the phrase “close proximity” is used to describe the disposition of the fuel metering chamber relative to the closure in the context of the fuel cell as a whole. The Full Court affirmed that considering functionality was appropriate to construction, finding that “the fuel metering chamber does not need to be positioned adjacent to, or as close as possible to, the closure in order for the internal valve fuel cell of the invention to be configured in a manner that operates more efficiently and effectively than the fuel cells described in the prior art incorporated by reference into the Patent. The words “in close proximity” do not require this.”^[5]

Interestingly, the Full Court also relied on dependent claims 3 and 7 of the patent to aid in construction of claim 1, albeit acknowledging that claim 7 provided a weaker support for the construction.

The Full Court highlighted that there is nuance in the construction of a word in different contexts within a specification. Their Honours found that “the word ‘opposite’ is sensitive to context”, and Justice Rofe’s construction of the term did not involve construing the word to have “different meanings” throughout the specification.^[6]

Finally, the Full Court rejected Airco’s criticism that Justice Rofe, to some extent, construed the claims contrary to the evidence of both parties’ experts. Their Honours held that “it is for the Court to determine the meaning of the language of the claims, aided by the evidence of experts to assist in understanding unfamiliar terms and the technical context of the subject matter”, and that “expert opinion does not supplant the judicial role”.^[7]

Conclusion

The Full Court has reaffirmed some key principles of patent construction, and has highlighted that the judicial role to construct patent claims cannot be usurped by expert evidence. It will be interesting to see whether these key issues will be expanded upon in future cases, and particularly how terms may be construed ‘sensitive to context’ throughout a specification.

At a practical level, for businesses and inventors seeking to obtain or enforce patents, this decision underscores the usefulness of carefully drafting and reviewing patent specifications to ensure that key terms and phrases are clearly defined and contextualised to support a broader interpretation of the claims.

—
^[1] Airco Fasteners Pty Ltd v Illinois Tool Works Inc [2023] FCAFC 7 at [7].
^[2] Illinois Tool Works Inc v Airco Fasteners Pty Ltd [2022] FCA 495 at [249].
^[3] Airco Fasteners Pty Ltd v Illinois Tool Works Inc [2023] FCAFC 7 at [4].
^[4] Ibid at [37].
^[5] Ibid at [55].
^[6] Ibid at [65].
^[7] Ibid at [59].

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