The scope of legal protection provided by a patent boils down to the interpretation of the claims. The drafting of claims has certain elements of art and tradition. One tradition is the use of the word "said" (or "the") when referring to a feature which has been previously mentioned in a claim.
This practice provides clarity, because the "said" feature is assumed to be the same as that previously mentioned, thus would have the same characteristics and limitations.
However, despite this traditional practice, in a recent Full Federal Court decision, the majority held that a "said" feature was not limited to the feature previously recited in the same terms, but could include other features not recited in the claims, thus broadening the strict literal meaning of the claim.
In Product Management Group Pty Ltd v Blue Gentian LLC the relevant patents concerned a portable garden hose which would increase in length and width on use. The scope and wording of the two patents was substantially the same. Claim 1 of the first patent included the following section, which was of key importance in this decision:
...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, 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...
Amongst all those uses of the word "said", the parties were in dispute about the interpretation of the phrase "said increase in water pressure".
Adopting a typical patent drafting approach, "said increase in water pressure" would be a reference to the increase in water pressure introduced in the previous line, i.e., the increase created by the fluid flow restrictor.
Blue Gentian argued that "said increase in water pressure" should be given a broad interpretation as the increase in water pressure could be due to factors in addition to the fluid flow restrictor (which a person skilled in the art would recognise).
The majority of Justices Kenny and Beach upheld the trial judge's decision, finding that the "said increase in water pressure" was broader than the "increase in water pressure" in the preceding line.
The majority acknowledged that their decision did not follow the traditional practice regarding interpretation of the word "said". However, adopting a purposive construction, as supported by the expert witnesses who gave evidence, a person skilled in the art would assume that the increase in water pressure referred to could include pressure increases resulting from the water flowing from a tap into the hose.
In his minority judgement, Justice Nicholas was not prepared to adopt a purposive construction for "said", repeating the general principle that "it is not permissible to vary or qualify the plain and unambiguous meaning of a claim by reference to the body of the specification". He found that the meaning of "said increase in water pressure" was limited to the increase introduced in the preceding line, and any difficulties a patentee may have in proving infringement under this interpretation was not a reason to vary the clear interpretation of the claim.
The interpretation of the majority of the Full Court appears broader than that intended by the patentees, given there was no mention of an increase in water pressure caused by any other means, including from flowing water, in either of the two patents in issue.
The result is less surprising when the underlying intention of a purposive construction is considered. A person skilled in the art would expect the water pressure from a tap into a hose to contribute to the overall water pressure in the system, so therefore the interpretation of the claims to include this additional element did not go beyond the scope of the claim. This is analogous to the facts in the Catnic case, in which the principles of purposive construction were introduced, wherein the word "perpendicular" was interpreted to mean "substantially perpendicular". However, the 2-1 decision shows that the outer limits of claim breadth as the result of a purposive approach to construction are not settled.
The majority sought to narrow the applicability of this decision to future cases, stating that the case before them was "one of those exceptional cases" where the usual literal meaning of "said" was not appropriate. However, a door has been opened in which claims can be broadened, perhaps beyond that originally envisaged by the patentee, by a purposive interpretation of non-technical terms, including those with a meaning widely accepted in patent law.