In district courts’ claim construction analyses, intrinsic evidence is of paramount importance. Although extrinsic evidence “may be useful to the court,” it is considered “less significant” than the claim language, specification, and prosecution history making up the intrinsic record. Phillips v. AWH Corp., 415 F.3d 1303, 1317 (Fed. Cir. 2005). Further, when “an analysis of the intrinsic evidence alone will resolve any ambiguity in a disputed claim term[,] . . . it is improper to rely on extrinsic evidence.” Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1583 (Fed. Cir. 1996).

Today, many district court patent infringement cases have co-pending inter partes review (IPR) proceedings in which the patent owner, accused infringer, and PTAB may make statements concerning the scope and meaning of claim terms of an asserted patent. Thus, a natural question is whether the IPR proceedings should be considered intrinsic or extrinsic evidence for purposes of claim construction in district courts.

The majority view is that IPR proceedings are intrinsic evidence. For example, in Evolutionary Intelligence, LLC v. Sprint Nextel Corp., the Northern District of California concluded that “[t]he IPR proceedings will add to the [patent’s] prosecution history,” which is “an important part of the intrinsic record relevant to claim construction.” 2014 WL 4802426, at *4 (N.D. Cal. Sept. 26, 2014); see also Corel Software, LLC v. Microsoft Corp., 2016 WL 4444747, at *2 (D. Utah Aug. 23, 2016) (noting potential for “additional intrinsic record develop[ment] during IPR”). Likewise, the Southern District of Texas found that the PTAB’s claim construction analysis in an IPR “serves as further intrinsic evidence” that must be considered by the court. Fairfield Indus., Inc. v. Wireless Seismic, Inc., 2015 WL 1034275, at *5 (S.D. Tex. Mar. 10, 2015).

Courts in the District of Delaware, Northern District of Texas, Western District of Tennessee, and Eastern District of Michigan, among others, have endorsed this view of IPR proceedings as intrinsic evidence. See Princeton Digital Image Corp. v. Konami Digital Entm’t Inc., 2017 WL 6375173, at *5 (D. Del. Dec. 13, 2017) (patent owner statements during IPR constitute prosecution history disclaimer); iLife Techs., Inc. v. Nintendo of Am., Inc., 2017 WL 525708, at *7 (N.D. Tex. Feb. 9, 2017) (same); Anglefix, LLC v. Wright Med. Tech., Inc., 2015 WL 9581865, at *7-8 (W.D. Tenn. Dec. 30, 2015) (prosecution history includes IPR proceedings); Signal IP, Inc. v. Fiat U.S.A., Inc., 2016 WL 5027595, at *16 (E.D. Mich. Sept. 20, 2016) (same).

Federal Circuit decisions appear to align with the majority view. For example, in Aylus Networks, Inc. v. Apple Inc. (discussed in a previous blog post: Aylus Networks), the Federal Circuit held that statements made in IPRs can operate as prosecution history disclaimer. 856 F.3d 1353, 1360-61 (Fed. Cir. 2017). In so holding, the court noted that extending the prosecution history disclaimer doctrine to IPR proceedings “promotes the public notice function of the intrinsic evidence.” Id. at 1360.

The majority view is further supported by the fact that post-issuance reexamination proceedings have always been considered intrinsic evidence. See, e.g., Info-Hold, Inc. v. Applied Media Techs. Corp., 783 F.3d 1262, 1266 (Fed. Cir. 2015); Nikken USA, Inc. v. Robinsons-May, Inc., 51 F’Appx 874, 884 (Fed. Cir. 2002); E.I. du Pont Nemours & Co. v. Phillips Petroleum Co., 849 F.2d 1430, 1439 (Fed. Cir. 1988). Because “an IPR proceeding [likewise] involves the reexamination of a patent” (Aylus, 856 F.3d at 1360), it may be reasonable to treat IPR proceedings as intrinsic evidence, similar to courts’ treatment of reexamination proceedings.


Most district courts consider IPR proceedings to be intrinsic evidence, and this view finds support in Federal Circuit law as well as similar prior treatment of reexamination proceedings. Accordingly, patent owners, accused infringers, and petitioners should carefully consider all statements made in IPR proceedings, understanding that such statements may be important evidence in construing claim terms in co-pending district court litigation. Further, although district courts generally do not defer to the PTAB’s claim constructions, the PTAB’s constructions and statements regarding those constructions will likely be considered part of the intrinsic record.