Text vs context in patent claim interpretation

The claims of a patent specification must “always be interpreted in their overall context and by reference to the object and description in the body of the specification”, as a recent decision of the Court of Appeal demonstrates. Hammar Maskin AB & Others v Steelbro New Zealand Ltd [2010] NZCA 83 is the first decision of an appellate court in a patent infringement case since the Supreme Court stated the rules for interpretation of a patent claim in Peterson Portable Sawing Systems Ltd v Lucas [2006] 3 NZLR 721 (SC) at [25]-[28]. (The rules include: “A patent specification is to be read as a whole and given a purposive construction.  It must be construed as it would be understood by the appropriate addressee - a person skilled in the relevant art.  Each part of the specification is to be read objectively in its overall context and in light of the function of that part.  The claims are to be interpreted by reference to the object and description in the body of the specification.”) 

It is also the first decision for many years to declare the claims of a New Zealand patent to be valid and infringed (for example, in Peterson v Lucas, the claim of the patent under consideration was declared by the Supreme Court to be invalid on the grounds of lack of novelty and obviousness). The Supreme Court has dismissed an application for leave to appeal (Steelbro New Zealand Ltd v Hammar Maskin AB & Others [2010] NZSC 65).

Background

The Court of Appeal’s judgment was an appeal from a decision of Justice Panckhurst in the High Court at first instance (Hammar Maskin AB & Others v Steelbro New Zealand Ltd (High Court, Christchurch CIV-2006-409-977, 8 October 2008)). The High Court held that the defendant, Steelbro New Zealand Ltd (Steelbro), had not infringed the patent of the plaintiffs, Hammar Maskin AB and others (Hammar), relating to a new support leg for a sidelifter. Sidelifters (or sideloaders as they are also known) are trucks fitted with hydraulic cranes to lift shipping containers onto the bed of the truck. A support leg provides stability to the sidelifter during the loading and unloading of the containers. In 2000, Hammar was granted a New Zealand patent for a new type of support leg that is stowed, prior to deployment, at a negative incline rather than horizontally as was known previously. A support leg stowed at a negative incline can extend further than a horizontally stowed leg and provides greater stability. Hammar and Steelbro each design and manufacture sidelifters with support legs and are the world’s two largest competitors in the industry. In 2004, Steelbro began to manufacture a sidelifter model (the SB361/401) with a support leg stowed at a negative incline and Hammar launched an action for patent infringement in the High Court. 

High Court

The High Court determined that Hammar’s patent was valid, but not infringed by Steelbro. The outcome of the trial centered on the meaning to be given to the disputed term “a bearing” in the phrase “an extension part which is movably arranged in a bearing in the first support part” that appeared in claim one of the patent. Steelbro submitted that the use of the indefinite article in the term “a bearing” required a separate bearing element to be present in order for the claim to be infringed. Steelbro presented evidence of Hammar’s subsequently manufactured sidelifter which contained internal sacrificial reinforcement plates between the two parts of the support leg and asserted this as confirmation that the claim required a separate bearing element. 

Hammar submitted that “a bearing” should be interpreted in light of the description of the invention in the patent specification, which did not describe or show in the drawings a separate bearing element, but which showed and discussed the extension part bearing on the first support part. The Judge accepted that the specification did not describe or show the existence of a separate bearing element, but considered (at [57]) that the phrase in the claim could “only be read as referring to an additional element which performs the function of a bearing”. Steelbro conceded that there was a bearing relationship between the inner part and the outer part of the support leg of its SB361/401 sidelifter, but argued, and the Judge agreed, that as the leg did not have a separate bearing element between the parts there was no infringement.

Court of Appeal

The Court of Appeal unanimously held that Steelbro’s sidelifter had infringed Hammar’s patent. The Court considered there was no doubt that the word “bearing”, taken alone, is capable of describing both a separate physical bearing component and also a state of bearing. The issue was which meaning should be preferred in the total context of the patent.

Steelbro submitted that the use of the indefinite article makes the meaning of the phrase clear and that, under New Zealand law, recourse can be made to the body of the specification only if the claims are ambiguous. The Court of Appeal rejected that submission and held that, following the rules for construction of a patent claim in Peterson v Lucas, the “claims must always be interpreted in their overall context and by reference to the object and description in the body of the specification” (at [48]). However, it was accepted that the specification can only assist interpretation and cannot modify the monopoly the inventor has clearly marked out in the claims.

Looking at the interpretation of the word “bearing” in the context of the specification as a whole, the Court of Appeal accepted Hammar’s submission that it was noteworthy that, despite the word “bearing” appearing in claim one, there was no reference in the specification to a separate “bearing” of the nature contended for by Steelbro, namely a discrete physical component situated in the outer support sleeve. Further, there was no separate physical bearing shown in the drawings. The Court reasoned that if there was intended to be an additional integer in the form of a separate bearing then one would expect that to appear in the specification and the drawings. What permeated the whole of the specification was instead the functional concept of bearing. Taking a purposive approach to the construction of the patent and construing claim one in the context of the specification as a whole, the Court of Appeal considered that the term “bearing” in claim one was used in a functional sense and that no separate bearing component was required.

Supreme Court

Steelbro applied to the Supreme Court for leave to appeal the decision of the Court of Appeal. The Supreme Court noted that neither party took issue with the Supreme Court’s statement of the rules for interpretation of a patent claim in Peterson v Lucas, with the contention being about how the Court of Appeal had applied those rules in the particular case. The Supreme Court was not persuaded that Steelbro had raised any arguable matter which was of significance other than to the parties themselves nor, in light of the principles stated in Peterson v Lucas, that there was any appearance of an error of such a substantial character that it would be repugnant to justice to allow it to go uncorrected. The Supreme Court also considered that the conclusion reached by the Court of Appeal could not be said to be obviously wrong. Leave to appeal was consequently dismissed.

Conclusion

The judgment of the Court of Appeal shows that, under New Zealand law, the body of a patent specification is always relevant to the interpretation of the claims, not just if the claims are ambiguous and capable of having more than one meaning. This is consistent with the law in the United Kingdom as stated by the House of Lords in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 169 (HL). Previously, the English courts gave a claim of a patent specification a literal interpretation based on the “plain meaning” of the language used in the claim (Electric & Musical Industries Ltd v Lissen Ltd (1939) 56 RPC 23 (HL) at 57). Only if the language of the claim was in itself ambiguous could the Court have regard to the context provided by the body of the specification. In Kirin-Amgen, Lord Hoffmann stated at [29] that this was a “highly artificial exercise” which was “capable of causing considerable injustice”, unless the Court could find some ambiguity in the language. The judgment of the Court of Appeal has clarified that such an exercise has no place in New Zealand’s patent law.

Henry Hughes & Co acted for Hammar both at first instance and on appeal.

By Frank Callus and Adrian Evans. This article appeared in New Zealand Lawyer Extra on 16 July 2010.