Full Court considers whether the word “device” in patent claims encompasses a tool in two parts

Australian Mud Company Pty Ltd (Australian Mud) was the patentee of Australian Innovation Patent No. 2006100113 (the patent).   The specification and claims of the patent were directed to an orientation device for providing an indication of the orientation of a core sample obtained by geological drilling.

Coretell Pty Ltd (Coretell), had an apparatus which provided the same functionality as the orientation device claimed in the patent. However, the apparatus consisted of two components, namely a down hole component and a handset component. At issue was whether the use of the word ‘device’ in the claims resulted in the claims being limited to an orientation tool of unitary construction, or encompassed an orientation tool consisting of separate parts.

The case was an appeal from an earlier Federal Court decision in which his Honour held that Coretell did not infringe the patent. While accepting that claims should be provided with a purposive construction, his Honour was mindful that such an approach does not permit the words in the claims to be extended beyond their literal meaning. His Honour concluded that the word “device” in the claims referred to a unitary construction.

Full Court Decision

Australian Mud considered that the primary judge erred in his claim construction by reading into the claims glosses drawn from the body of the specification, namely that the device was of unitary construction. It should be noted that the best method of performing the invention was described in the specification with reference to a specific embodiment, which both parties agreed was an orientation device having a single, unitary assemblage.

The Full Court acknowledged that the primary judge had applied the established principles of purposive claim construction derived from the relevant cases. Their Honours endorsed the approach of the primary judge and made the observation (at [69]) 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”.

At [72], their Honours also 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.”

Coretell put forward that a proper construction of the claims required consideration of all of the words of the claims, rather than merely focussing on the word “device”. The Full Court accepted Coretell’s submissions regarding claim construction as, in contrast to the construction contended by Australian Mud, Coretell’s construction provided a consistent meaning to the word “device” throughout the claims.

The Court upheld the decision of the primary judge finding that he properly construed the claims in the context of the invention with no reference from the body of the specification being imported into his construction of the claims.


The decision highlights how critically important it is to carefully select the language used in patent claims. The decision also serves as a reminder of the importance of describing multiple embodiments in a specification, and drafting claims in a manner which captures all embodiments and workable modifications of an invention which commercial competitors may otherwise implement to avoid infringement.