Appeal 2007-0493
Application 10/289,967
Patent 6,144,380
***
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 could not reasonably be
expected to have drafted a claim that would have literally
encompassed the alleged equivalent (emphasis added).
The same policy considerations that prevent a patentee from urging
equivalents within what the Supreme Court refers to as “surrendered
territory” should prima facie prohibit the patentee from being able to claim
subject matter within the surrendered territory in reissue. Accordingly, the
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