Appeal 2007-0700
Application 09/159,509
Patent 5,559,995
record.”). Moreover, whether an amendment was merely
tangential to an alleged equivalent necessarily requires focus on
the context in which the amendment was made; hence the resort
to the prosecution history. Thus, whether the patentee has
established a merely tangential reason for a narrowing
amendment is for the court to determine from the prosecution
history record without the introduction of additional evidence,
except, when necessary, testimony from those skilled in the art
as to the interpretation of that record.
. . . When at all possible, determination of the third rebuttal
criterion should also be limited to the prosecution history
record. . . . We need not decide now what evidence outside the
prosecution history record, if any, should be considered in
determining if a patentee has met its burden under this third
rebuttal criterion.
We interpret Festo III to generally, perhaps effectively, limit the
admissible rebuttal evidence to the prosecution history record and extrinsic
evidence related to the knowledge of the hypothetical person of ordinary
skill in the art at the time of the amendment. Admitting evidence not
available to the public, such as an affidavit of an attorney giving mental
impressions from the attorney who made the amendment, would undermine
the public notice function of the patent and its prosecution history.
(12)
Materially Narrowed in Overlooked Aspects
When reissue claims are narrower than the patent claims with respect
to features other than the surrender generating feature, then the reissue
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