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Introduction
Claim interpretation is a central issue in every patent
system. In any patent infringement action, it is necessary to
establish both whether a patent is valid and whether that patent is
infringed. It is very rare for an allegedly infringing product or
process to be an exact copy of what is described in a patent. This
means that at trial a patentee will have to argue that despite the
existence of differences, an alleged infringement still falls within
the scope of the patent. In response a defendant will usually deny
that there is infringement and will seek to establish that his
product or process is not covered by the claims or that, if a patent
has sufficient breadth to cover the defendant’s activities, the
patent is obvious or anticipated.
Ideally, patent
claim language would always be so clear and unambiguous that there
would be no dispute as to its meaning. The English and American
courts have long accepted, however, that perfect clarity is
impossible to achieve and that it is therefore necessary to
interpret the meaning of claims. Thus, for example in Autogiro
Co. v. America v. United States
[1] the U.S. Court of Claims
stated:
Claims cannot be
clear and unambiguous on their face. A comparison must exist. The
lucidity of a claim is determined in light of what ideas it is
trying to convey. Only by knowing the idea, can one decide how much
shadow encumbers the reality.
The very nature of words would make a clear and unambiguous claim a
rare occurrence. … An invention exists most importantly as a
tangible structure or series of drawings. A verbal portrayal is
usually an after thought written to satisfy the requirements of
patent law. This conversion of machine to words allows for
unintended idea gaps which cannot be satisfactorily filled. Often
the invention is novel and words do not exist to describe it. The
dictionary does not always keep abreast of the inventor. It cannot.
Things are not made for the sake of words, but words for things.
Although the methods used by the English
and American courts to interpret patent claims have many
similarities, both countries have developed distinctive approaches
as to how such claims should be interpreted. Both in the U.S. and
the U.K. special rules exist for interpreting the scope of certain
claim formulations.[2]
However, rather than considering the construction of such special
claim types, the present article will compare the approaches
normally applied to claim construction by the English and American
courts and examine these different approaches in the historical
context of the development of the English and American patent
systems.
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