Interpretation of patent claims
The recent case of Ancon Limited v ACS Stainless Steel Fixings Limited has
highlighted the UK Court of Appeal’s attitude towards interpretation of patent
claims. Claim interpretation is of particular importance because the interpretation
adopted by a court can be pivotal in determining whether a patent is held infringed
and/or invalid.
The patent at issue related to channel assemblies used in the construction industry
to fix components to a building. In the initial decision, the High Court held that
ACS’s assembly did not infringe Ancon’s patent. However, on appeal by Ancon, the
Court of Appeal held that the High Court had interpreted the claimed feature“generally elliptical cone shape” too narrowly and so was wrong to find noninfringement
by ACS. The Court of Appeal held that the claimed feature should in
fact be interpreted more broadly as “any rounded non-circular form”. The ACS
assembly fell within this broader interpretation and so the ACS device was held to
infringe Ancon’s patent.
In its reasoning the Court of Appeal emphasised that it had come to its conclusion
by using the claim construction test established by the UK House of Lords, in which
the court determines what the person skilled in the art would have understood the
patentee to have used the language of the claim to mean.
Following the EPC2000 law changes that came into effect in December 2007,
European patent law now requires that “due account” should be taken of any
element that is equivalent to an element specified in the claims but which the claim
language does not literally cover. However, the Court of Appeal indicated that it did
not rely on any rule of equivalents in coming to its decision and indeed suggested
that the new language used in EPC2000 was not intended to change the law on this
subject.
This decision is a clear signal that the Court of Appeal does not favour use of
equivalents in interpreting claims, and emphasises the importance of careful
drafting of the entire patent specification, since before a UK court it might not be
possible to successfully rely on a doctrine of equivalents in a potential case of patent
infringement.
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