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

Airco Fasteners Pty Ltd v Illinois Tool Works Inc [2023] FCAFC 7

13 February 2023

Full Federal Court of Australia

Rares, Moshinsky and Burley JJ 

Highlight 

This decision provides a good example of the principles of claim construction in operation, and provides a helpful reminder that construction is a matter for the Court.   The decision underscores the importance of careful and precise drafting ensuring that key terms and phrases are clearly defined and contextualised to support a purposive interpretation of the claims. 

Background 

In this Full Court decision, Airco’s appeal on the claim construction adopted by Justice Rofe at first instance in Illinois Tool Works Inc v Airco Fasteners Pty Ltd [2022] FCA 495 was dismissed, and consequently Airco was found to infringe ITW’s patent. 

Illinois Tool Works Inc (ITW) is the owner of Australian Patent no 2005232970 titled “In-can fuel cell metering valve” relating to a fuel cell designed for use with combustion tools like nail guns.  This fuel cell includes an internally mounted metering valve that dispenses a measured dose of fuel each time its stem is pressed into the open position.   

Claim 1 specifies several key features, including the requirement for the fuel metering chamber to be in close proximity to the closure, and the presence of a valve body with a second end opposite the fuel metering chamber located within a separate fuel container.   

ITW commenced proceedings against Airco Fasteners Pty Ltd (Airco) for infringement of various claims of the patent in relation to a combustion tool fuel cell supplied by Airco.  Airco did not challenge the validity of the patent.   We reported on the decision of Justice Rofe at first instance, addressing both the infringement claim and amendments sought by ITW, in our 2022 Patent Case Summary. 

Since validity of the patent was not in issue, the question of infringement depended on claim construction of the key terms “close proximity” and “opposite”.  As was noted by Justice Rofe at first instance, claim construction is a matter for the Court.  Her Honour found that that the Airco Fuel Cell infringed ITW’s patent based on her construction.   

Airco filed an appeal with the Full Federal Court contending that Her Honour’s construction was wrong. 

Key Issues 

The appeal related to these two construction issues.   

The principles of claim construction under Australian law are well known.  These include: 

• The proper construction of a specification is a matter of law. 
• A patent specification should be given a purposive, not a purely literal, construction. 
• The words used in a specification should be interpreted based on how a person skilled in the art would understand them. 
• While claims should be construed in the context of the specification, it is not permissible to expand or narrow their boundaries by adding glosses from other parts of the specification. 
• Experts may assist the Court by providing evidence on construction, but this is ultimately a matter for the Court. 

At first instance, Her Honour held the term “close proximity” implies a relative nearness of the fuel metering chamber to the closure within the context of the entire fuel cell.  The requirement is functional, aiming to ensure that the fuel metering chamber is sufficiently close to the closure for efficient and safe fuel metering and dispensing during combustion tool operation.  Her Honour highlighted that the objectives of the patent included minimising fuel and propellant leakage and ensuring precise fuel emission.  Rejecting Airco’s submissions, she held there was not requirement that the two components be adjacent, or as close as possible, to achieve this.    

On appeal the Full Court agreed with Justice Rofe that the term was not to be determined solely by the relative location of those two components alone but in the context of the fuel cell as a whole.  Notably, as the size and length of the fuel cell is not specified in the patent specification, such lack of precise dimensions does not invalidate the claim as long as it provides a workable standard suitable for its intended use, reflecting the purposive approach to claim construction.  The Full Court was of the view that the primary judge correctly considered functional aspects when interpreting the “close proximity” requirement to ensure the fuel metering chamber allows efficient operation of the fuel cell. 

Justice Rofe also held “opposite” in the context of the “second end opposite” integer to mean that the second end of the valve be “facing” or “across from” the fuel metering chamber, implying a spatial relationship between those two components across the same axis.  The Full Court agreed, rejecting Airco’s proposed interpretation that “opposite” had a different meaning in this context, referring to one end of the valve relative to its other end (similar to a first end and a second end), as not supported by the claims and inconsistent with the drawings presented in the patent specification. 

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. 

Finally, the Full Court rejected Airco’s criticism that Justice Rofe construed the claims contrary to the evidence of both parties’ experts, reminding the parties 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”, as “expert opinion does not supplant the judicial role”. 

Implications 

Key takeaway points from Full Court’s decision can be summarised as follows: 

1. Claim Construction is Crucial: The decision underscores the critical importance of clear and correct claim construction in patent litigation. The Court’s role in construing these claims is central to resolving patent disputes.
    
2. Functional Interpretation: Functionality and the broader context of an invention can be key considerations in claim construction.  In this case, the term “close proximity” was construed not just in terms of physical location but in the context of the entire fuel cell’s efficient operation.  This emphasises the need to consider the practical function of the claimed features.
    
3. Expert Testimony Is Important but Not Determinative: Expert witnesses may play a critical role in providing insights into technical matters and helping the Court understand the nuances of a patent’s construction, albeit that the final say on interpretation resides with the Court.  But ultimately it is the Court’s role to construe the claims, not the expert’s.  This means that the Court may adopt or reject the construction proffered by an expert, or adopt an alternative construction.
    
4. Dependent Claims Provide Support: It is known that dependent claims within a patent can provide valuable support for the interpretation of key terms in independent claims.  In this case, dependent claims 3 and 7 were cited to support the construction that the relative location of components should be assessed based on the fuel cell as a whole.   

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 purposive interpretation of the claims. 

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