Case: Seafood Innovations Pty Ltd v Richard Bass Pty Ltd  FCAFC 83
The fish stunning machine covered by the patents had a fish stunning device, a fish guide and a trigger. The fish is moved in one direction from an entrance to an exit.
Relevantly, one of the claims set out: "the fish guide includes a floor being pivotally mounted between a first position and a second position, the floor moving from the first position to the second position to allow a fish to pass unidirectionally from the entrance to the exit".
The Bass devices included a pivotally mounted floor which moves from the first position to the second position. But they also included a cheek plate and a top plate. So the three devices acted together as a sphincter to allow the fish to pass unidirectionally. Bass contended that the devices did not infringe the claim because it was not the floor alone that allowed the fish to pass.
A common sense construction was adopted. There was evidence from a skilled addressee that the Bass devices and the apparatus of the claims of the first innovation patent operated in the same way and that there is no practical difference in terms of the purpose of the apparatus in this context.
Bass pointed out that the pivotally moveable floor was the only description of the fish guide in the specification. The description stated that the fish guide “comprises” (in the sense of consists of) the floor. Bass said that that made the pivotally moveable floor an essential integer of the invention which must, therefore, be included in the claims. On the other hand, Seafood Innovations said that the description of such a fish guide is but one embodiment of the apparatus broadly described, without any such limitation.
Bass followed the incorrect approach of seeking to isolate essential integers from the body of the specification in understanding the claimed invention. As held in Lockwood Security v Doric Products  HCA 58, a narrow embodiment of a broad claim does not render the claim invalid for lack of fair basis.
Perhaps the most important message to come out of this decision is the reference to "common sense". It is always necessary to adopt a common sense construction. In order to do so, we always need to refer back to the skilled addressee and how he/she might read the document.