Appeal No. 2005-0642
Application No. 09/568,278
[Prosecution history estoppel’s] reach requires an examination of the
subject matter surrendered by the narrowing amendment. [A]
complete bar [would avoid] this inquiry by establishing a per se rule;
but that approach is inconsistent with the purpose of applying the
estoppel in the first place-to hold the inventor to the representations
made during the application process and to the inferences that may
reasonably be drawn from the amendment (emphasis added).
***
A patentee’s decision to narrow his claims through amendment may
be presumed to be a general disclaimer of the territory between the
original claim and the amended claim. Exhibit Supply, 315 U.S., at
136-137, 62 S. Ct. 513 (“By the amendment [the patentee] recognized
and emphasized the difference between the two phrases and
proclaimed his abandonment of all that is embraced in that
difference”). There are some cases, however, where the amendment
cannot reasonably be viewed as surrendering a particular equivalent.
The equivalent may have been unforeseeable at the time of the
application; the rationale underlying the amendment may bear no
more than a tangential relation to the equivalent in question; or there
may be some other reason suggesting that the patentee could not
reasonably be expected to have described the insubstantial substitute
in question. In those cases the patentee can overcome the
presumption that prosecution history estoppel bars a finding of
equivalence (emphasis added).
***
When the patentee has chosen to narrow a claim, courts may presume
the amended text was composed with awareness of this rule and that
the territory surrendered is not an equivalent of the territory claimed.
In those instances, however, the patentee still might rebut the
presumption that estoppel bars a claim of equivalence. The patentee
must show that at the time of the amendment one skilled in the art
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