The prosecution history, which “consists of the complete record of the proceedings before the [patent office] and includes the prior art cited during the examination of the patent,” is intrinsic evidence that properly may be considered in claim construction. Phillips v. AWH Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005). “Courts must take care . . . to interpret purported disavowals in the context of the prosecution history as a whole.” Azurity Pharms., Inc. v. Alkem Lab'ys Ltd., 133 F.4th 1359, 1366 (Fed. Cir. 2025). Prosecution disclaimer may not apply when a reasonable reader of the prosecution history could conclude that the examiner rejected the applicant's characterization of the scope of its invention. See Ecolab, Inc. v. FMC Corp., 569 F.3d 1335, 1342 (Fed. Cir. 2009) (“Even if an isolated statement appears to disclaim subject matter, the prosecution history as a whole may demonstrate that the patentee committed no clear and unmistakable disclaimer.”); Malvern Panalytical Inc. v. TA Instruments-Waters LLC, 85 F.4th 1365, 1376 (Fed. Cir. 2023) (“[W]here an applicant abandons its unsuccessful argument, we conclude that the prosecution history lacks the clarity necessary to establish prosecution disclaimer.”). 

In Ecolab, the patentee, FMC, attempted to overcome prior art rejections by arguing that its claims contemplated using peracetic acid (“PAA”) as the only antimicrobial agent. Id., 569 F.3d at 1343. But the examiner rejected that argument, concluding that the pending claims were not so limited. See id. (noting that the examiner concluded that “the terminology ‘consisting essentially' does not mean that [FMC's] sanitizing solution is consisted ‘solely' of a peracetic acid solution”). FMC never raised that argument again and overcame the rejections on other grounds. Id. Consequently, the prosecution history did not contain a sufficiently clear disclaimer because a reasonable reader of the prosecution history could conclude that FMC's statement regarding the scope of its claims was made in error; the examiner corrected that error; and FMC acquiesced to the examiner's correction. Id.

In Malvern, an applicant's statements regarding the scope of the invention did not rise to the level of disclaimer where the examiner rejected the applicant's prior characterization of the patent-at-issue. 85 F.4th at 1376. There, Malvern accused TA Instruments-Waters (“Waters”) of infringing its patent on an isothermal titration calorimeter (the “ITC patent”). Id. at 1367–68. During the prosecution of an unrelated application, also assigned to Malvern, the examiner rejected several claims as anticipated by the ITC patent. Id. at 1370 & n.3. In response, the applicant argued that the ITC patent disclosed only manual systems whereas the application concerned automatic systems. Id. Reading the ITC patent as encompassing both manual and automatic systems, the examiner disagreed; consequently, the applicant had to overcome the rejection on other grounds. Id. In the subsequent infringement action, the district court concluded that the ITC patent was limited to manual systems based on the disclaiming statements made during the prosecution of the unrelated application. Id. at 1371. The Federal Circuit vacated the district court's construction, in part, because a reasonable reader of the application's prosecution history could conclude that the applicant “recognized its error” when assessing the scope of the ITC patent and “acquiesced to the examiner's views.” Id. at 1376 (quoting Ecolab, 569 F.3d at 1343).

In Barrette Outdoor Living, Inc. v. Fortress Iron, LP, No. 2024-1231, __ F.4th ___ (Fed. Cir. Oct. 17, 2025), the Federal Circuit stated that “in both Ecolab and Malvern, the patentee was not held to a narrower construction advanced during prosecution because a reasonable reader of the file wrapper could conclude that those arguments did not accurately reflect the proper scope of the claims.”

     Moreover, the fact that an applicant secures allowance on an independent ground does not render prior characterizations of claim scope insufficiently clear for purposes of prosecution disclaimer. See Uship Intell. Props., LLC v. United States, 714 F.3d 1311, 1315 (Fed. Cir. 2013) (holding that the prosecution disclaimer analysis “focuses on what the applicant said, not on whether the representation was necessary or persuasive”). Here, although Barrette maintains that the examiner rejected the view that the claims required an integral boss, the examiner disagreed not with Barrette's characterization of the “boss” term in its own claims but with Barrette's assessment of the scope of Sherstad's disclosure. See J. App'x 515 (indicating that Sherstad disclosed a boss that “can either be integral with the clip 130, or be a separate pin member”). Unlike the prosecution histories in Ecolab and Malvern, the prosecution history of the '075 patent does not suggest that the examiner disagreed with Barrette's assessment of the scope of its claims, much less that Barrette acquiesced to the examiner's broader view of the claims. Thus, the prosecution history would not suggest to a reasonable reader that Barrette's narrowing characterization of its claims was incorrect. 
     Without an indication that Barrette's characterization of its claims was erroneous, the prosecution history would lead a reasonable reader to conclude that Barrette clarified the scope of the claimed invention and that the claimed invention was not patentable over the examiner's prior art rejection. See J. App'x 515. The fact that Barrette's disclaimer proved unavailing does not render it ineffective as a disclaimer. See Uship, 714 F.3d at 1315 (“The fact that the applicant may have given up more than was necessary does not render the disclaimer ambiguous.”). Accordingly, we conclude that Barrette clearly characterized the claimed invention as limited to integral bosses, and the subsequent communications with the patent office do not render Barrette's disclaimer ambiguous. 

The Federal Circuit further noted that “[w]hile applicants may rescind a disclaimer made during prosecution when the applicant puts the examiner on notice that previously examined prior art may need to be revisited, . . . [it was] conceded during oral argument that it did not make such a rescission here.” 

In short, the prosecution history for a subsequent continuation application can apply to the claims of an already issued patent that is related as part of the same patent family. Indeed, as previously noted in Teva Pharms. USA, Inc. v. Sandoz, Inc., 789 F.3d 1335, 1343 (Fed. Cir. 2015): “A statement made during prosecution of related patents may be properly considered in construing a term common to those patents, regardless of whether the statement pre- or post-dates the issuance of the particular patent at issue.” 

Thus, non-infringement was affirmed because the district court correctly determined that the patentee retroactively disclaimed non-integral bosses during prosecution of a later-filed continuation application. 

Noting that “[m]ost US patents are part of a larger family and the risk created by these decisions has potential implications for a large number patent holders,” Professor Crouch suggested “one solution would have been to amend the continuation to spell out the limitation rather force the limitation by argument.”