This case demonstrates the difficulties of invalidating a claim due to lack of clarity.
This has two main implications. Firstly, in approaching the task of claim construction for claims with substantial clarity issues, one must broadly consider the purpose of the invention and apply an interpretation that is consistent with its purpose even if that deviates substantially from the normal meaning of words used in the claims. Secondly, while this decision was favourable to the Patentee, it is easy to imagine a situation where unclear features in a claim are given an interpretation that broadens the claim so that it is rendered invalid, or that narrows the claim further than intended.
Blue Gentian (BG) is the patentee of a patent covering an expandable hose including a first coupler for attachment to a faucet, and a second coupler where water is discharged. The second end of the hose includes a flow restrictor to increase the pressure drop along the hose to expand the hose.
BG alleged that Product Management Group (PMG) infringe their patent due to the supply of an expandable garden hose having a flow restrictor. PMG denied infringement and cross-claimed for revocation of the patent. The Trial Judge found in favour of BG. PMG appealed the decision, in part, arguing improper claim construction. The Full Federal Court upheld the Trial Judges’ decision.
While a number of claim construction issues were considered in the appeal, the key argument relied on the interpretation of the word "said". The word "said" is commonly used in patent claim drafting to explicitly refer back to a feature earlier defined in the claim. This usage is consistent with its everyday meaning. The issue of the meaning of the word "said" arose around claim Features identified as 1.7 and 1.8 respectively:
1.7 …said second coupler also coupling said hose to a fluid flow restrictor or including a fluid flow restrictor so that the fluid flow restrictor creates an increase in water pressure between said first coupler and said second coupler within said inner tube…
1.8 …said increase in water pressure expanding said elongated inner tube longitudinally along a length of said inner tube and laterally across a width of said inner tube thereby substantially increasing a length of said hose to an expanded condition…
It’s worth noting that Feature 1.7 provides the first reference to "…an increase in water pressure…" and provides antecedent basis for this term.
Despite the serious clarity issues with Feature 1.7, PMG contended that the claim explicitly required the fluid flow restrictor to create an increase in water pressure that was alone causative of the increase in length of the hose, arguing that the use of the phrase "…said increase in water pressure…" in Feature 1.8 further characterised the feature of "…an increase in water pressure…" in Feature 1.7.
In an apparent departure from claim drafting norms, the Trial Judge (upheld by the Full Federal Court) considered that "…said increase in water pressure…" in Feature 1.8 did not literally refer back to "…an increase in water pressure…" caused by the flow restrictor in Feature 1.7. Instead, "said" should be provided with a broader interpretation that includes other mechanisms by which the increase in water pressure could be achieved (such as due to friction losses).
The multiple construction issues stemming from the use of incorrect language was beneficial to the Patentee and contributed to this unorthodox interpretation of the word "said." The Full Federal Court commented that given these errors in language it was less of a step to accept that there were other imprecisions – for example, one of the uses of the word "said"1.
Ultimately, the decision that the word "said" should not be given a strictly literal interpretation came down to applying a purposive construction to the invention. The Full Federal Court was of the view that in reading the claims in the context of the specification as a whole, the skilled addressee would appreciate that the literal meaning of "said" was not being used.
Implications of this decision
The meaning of the word said
When drafting claims, there is always a balance between choosing words which provide breadth to a claim and choosing narrow terms having a clear and literal meaning. In the majority decision the Full Federal Court stated that this case is "one of those exceptional cases where a skilled addressee would not construe the word "said" in such a literal way"2. However, there is little guidance as to what makes a case "exceptional", it seems that an "exceptional" case is one where the claims have serious clarity issues.