Opinion ID: 211104
Heading Depth: 3
Heading Rank: 2

Heading: Argument-based Estoppel

Text: 83 Next, EEI contends that Conoco is also estopped by the repeated arguments the patentees made to explain the term fatty acid wax during prosecution. EEI maintains that the patentees cannot claim an equivalent because it specifically limited the term by arguing that fatty acid wax referred to stearamides and did not include metal stearates. To invoke argument-based estoppel, however, the prosecution history must evince a clear and unmistakable surrender of subject matter. Deering Precision, 347 F.3d at 1326 (citation and punctuation omitted). Unlike amendment-based estoppel, we do not presume a patentee's arguments to surrender an entire field of equivalents through simple arguments and explanations to the patent examiner. Though arguments to the examiner may have the same effect, they do not always evidence the same clear disavowal of scope that a formal amendment to the claim would have. Compare Festo, 535 U.S. at 739, 122 S.Ct. 1831 (requiring courts to presume that the patentee surrendered all subject matter between the broader and the narrower language when an amendment is made for purposes of patentability) with Deering Precision, 347 F.3d at 1326 (requiring the prosecution history to evince a clear and unmistakable surrender of subject matter before estopping an equivalents argument). The relevant inquiry is whether a competitor would reasonably believe that the applicant had surrendered the relevant subject matter. Cybor, 138 F.3d at 1457. 84 Here, for instance, there is clear surrender of metal stearates, but there has not been a clear surrender of other possible equivalents. As the examiner noted, applicant [showed] the criticalities of using fatty acid wax as the partitioning agent over metal stearates  in a video presented to the examiner. In reference to stearamides, the patentees merely explained what a fatty acid wax was and how it operated in the invention. The prosecution history arguments here merely demonstrate to the examiner that a fatty acid wax was not the same as a metal stearate to alleviate the examiner's obviousness concerns. Though this may be enough to clearly disavow metal stearates as equivalents of fatty acid waxes, it is not a clear surrender of all fatty acid wax equivalents. 85