Don’t rely on purposive construction to extend the scope of a patent claim
Australian Mud Company Pty Ltd v Coretell Pty Ltd  FCAFC 121 (15 September 2011)
A recent decision of the Full Federal Court has highlighted the need to carefully consider the language used in a patent claim, and in particular to ensure that it is broad enough to capture any workable variants which might be adopted by an infringer. The Court found that a claim to “a device” was to the device formed as a single part, and did not cover devices formed as two (or more) parts.
The decision at first instance
The case was an appeal from an earlier decision of the Federal Court in which Justice Barker held that Coretell did not infringe the claims of Australian Mud Company’s innovation patent concerned with drill core orientation tools used in the mining industry. The claims of the patent were directed to “an orientation device” and this was interpreted by His Honour, applying well-established principles of claim construction, to mean a device formed of a single part. Because Coretell’s orientation tool contained two parts (a down hole component and a handset) it was found to fall outside the scope of the claims.
Australian Mud Company appealed to the Full Court on the ground that the primary judge had incorrectly applied the rules of construction, and argued that “device” should be construed more broadly as a result.
The Full Federal Court’s findings
The Court considered the manner in which the primary judge had applied purposive construction in order to reach his conclusion. Purposive construction is a well-established rule of claim interpretation which is intended to avoid unduly limiting the scope of a claim, as might occur if a strictly literal approach was taken.
The Court noted (at ) that cases such as Catnic, while encouraging purposive construction, “did not propound any novel principle or new category of ‘non-textual infringement'”. Their Honours also held (at ) that
“To give a purposive construction to a patent specification, and in particular its claims, is not to engage in a process of reasoning that extends the patentee’s monopoly to the ‘ideas’ disclosed in the specification. Nor does it extend the patentee’s monopoly to products or processes that the patentee did not, by the claims, define as the invention, even if those products or processes can be seen to perform the same function as the invention or to be based on the patentee’s ‘ideas’.” (emphasis added)
The Court agreed with the primary judge’s observation that
“… there is no warrant for adopting a method of construction that gives a patentee what it might have wished or intended to claim, rather than what the words of the relevant claim actually say. While the Court should read the claims purposively and not with an eye for pedantry, even an appropriately liberal approach to construction should not permit the words of the claims to be stretched beyond their textual limits.” (emphasis added)
It was further held, in acceptance of Coretell’s submissions, that Australian Mud Company’s submissions focused too heavily on the meaning of the word “device” considered in the abstract, rather than in the context that it was used in the claims. The Court found that the construction contended for by the patentee required the word “device” to have different meanings within different parts of the claim, whereas the construction contended for by the alleged infringer gave a consistent meaning to the word “device” throughout.
The Court dismissed the appeal, finding that the primary judge had properly construed the claims in the context of the specification, and that the construction of “device” as a unitary device was correct.
Lessons for patentees
The approach taken by both the primary judge and the Full Court on appeal reinforces the fact that purposive construction will not allow a patentee to claim more than what is in the words of the claims themselves.
The case also provides a reminder that if a patent applicant can conceive of any workable variations to the invention which an infringer might adopt, even if the applicant would never adopt those variations themselves, it is advisable to include them in the specification at filing in order to make it clear that they are intended to be covered by the claims. It is likely, of course, that the patentee in this case never envisaged an orientation tool formed as two separated parts.