When Maintenance Fees Lapse: Unexpected Consequences at the USPTO, PTAB, and in District Court

Introduction

The USPTO requires patent owners to pay maintenance fees for utility patents at 3.5 years, 7.5 years, and 11.5 years after issuance, with each deadline allowing a six-month grace period for payment.[1] It is widely known that if a patent owner fails to pay its maintenance fees, the patent lapses and goes into the public domain.[2] But failure to pay these fees can have additional unforeseen consequences before the USPTO and in district court.

For example, missed maintenance fees could affect the “settled expectations” factor in discretionary denial considerations for inter partes review (IPR) petitions.[3] It could also affect the claim construction standard applied to claims during ex parte reexamination.[4] Missing even one payment could open the door to intervening rights, allowing others to make and use the patented invention even after the patent is revived.[5] Should a patent be revived after having lapsed due to maintenance fee non-payment, inequitable conduct could also become an issue.[6]

With these serious ramifications, patent owners and others, e.g., accused infringers, should be vigilant about the status of maintenance fee payments.

Unpaid Maintenance Fees: What Should And Shouldn’t A Patent Owner Do?

In the event a patent owner misses a maintenance fee payment, all may not be lost as the patent owner may be able to reinstate the patent.[7] First, each maintenance fee deadline enjoys a six-month grace period.[8] If failure to pay is discovered within the six-month grace period, a patent owner may simply pay the fee along with any applicable surcharges.[9] But if the six-month grace period has expired, the patent can be revived only if non-payment was “unintentional,”[10] including “the period from discovery that the maintenance fee was not timely paid until payment of the maintenance fee.”[11]

To revive a lapsed patent, the patent owner must file a petition that includes, among other things, “a statement that the delay in payment of the maintenance fee was unintentional.”[12],[13] USPTO regulations do not formally put a time limit on when such a petition must be filed,[14] but the Office clarified its practice in 2020 “as to situations that will require additional information about whether a delay in seeking…acceptance of a delayed maintenance fee payment…was unintentional.”[15] If more than two years have passed since the patent expired for non-payment, patent owners must explain why the entire delay was unintentional.[16] On the other hand, if a patent owner petitions within two years of the patent lapse, the patent owner needs only to certify that “[t]he delay in payment of the maintenance fee was unintentional.”[17] The rationale behind these different burdens is simple: a delay of “more than two years…from the date the patent expired” suggests there is a “greater likelihood that the entire delay may not be ‘unintentional.’”[18]

But what does “unintentional” mean in practice? Can mistakes of fact that lead to a missed payment qualify? The Federal Circuit considered this question in Network Signatures, Inc. v. State Farm Mutual Auto Insurance, Co.[19] There, the patent owner chose not to pay a maintenance fee because he was unaware of any commercial interest in the patent.[20] The patent owner “made maintenance fee payment decisions once or twice a year, and…’if there is an expression of interest, the [patent owner] will pay the nominal maintenance fee,’ but will ‘allow the patent to go abandoned’ as a matter of ‘routine practice’ absent any ‘identified commercial interest.’”[21] Two weeks after the patent lapsed for maintenance fee non-payment, the patent owner learned a party was interested in licensing the patent.[22] The potential licensee had been trying to reach the patent owner well before the final payment date, but was unable to reach the patent owner until two weeks after the patent had lapsed.[23] Having learned of the licensing inquiry, the patent owner petitioned the USPTO that same day to accept a delayed payment using the USPTO’s standard form, which included a pre-printed statement saying “[t]he delay in payment of the maintenance fee to this patent was unintentional.”[24] The Federal Circuit found the patent owner’s non-payment under these particular circumstances to be unintentional and did “not agree that this action constituted material misrepresentation with intent to deceive.”[25] The court reasoned the patent owner complied with the USPTO’s standard procedure for delayed payment, used the standard USPTO form, and promptly acted upon learning of the commercial interest in the patent.[26] Thus, Network Signatures suggests that a mistake of fact that there is no commercial interest in a patent that might lead to non-payment of a maintenance fee could be considered unintentional so long as the patent owner acts promptly.[27]

Five years later, in In re Rembrandt, the Federal Circuit considered the meaning of “unintentional” in the context of inequitable conduct. There, the court affirmed the district court’s finding that certain patents were unenforceable due to inequitable conduct, in part, because it found the patent owner falsely represented to the USPTO that its failure to pay maintenance fees was “unintentional.”[28] The patent owner in Rembrandt sought to revive certain patents only after learning there was commercial interest in them, claiming that the lapsed payment was a mistake of fact—employees of the patent owner responsible for the patent portfolio “genuinely believed that a patent could be revived for years even after the six-month grace period.”[29] The Federal Circuit, however, rejected the “mistake of fact” argument in light of evidence of the patent owner’s deliberate decision to allow the patent to lapse such that the non-payment could not be characterized as unintentional within the meaning of 37 C.F.R. § 1.378(a).[30] For example, the patent owner’s “explanation” was “difficult to square” with documents “indicating that it was [the patent owner’s] surprise that a third party might have interest in the  abandoned patents that prompted their revival.”[31] Moreover, the evidence showed that the same individuals[32] who certified to the USPTO that the delay in payment was unintentional not only decided which patents to abandon, but also knew that failure to pay maintenance fees would result in the patents’ expiration.[33] A “variety of other misconduct” indicated that “intent to deceive the PTO [was] the single most reasonable inference able to be drawn from the evidence.”[34] Indeed, in light of the evidence, the patent owner’s “claim of mistake was a post hoc rationalization”[35] that did not override patent owner’s deliberate decision not to pay the maintenance fees.[36]

The Federal Circuit went on to distinguish the circumstances in Rembrandt from those in Network Signatures. In Network Signatures, there was no evidence to contradict the patent owner’s representation that the lapsed maintenance fee was a result of a mistake, as opposed to the evidence in Rembrandt, which showed the patent owner made a deliberate decision that warranted a finding of inequitable conduct.[37]In addition, the patent owner made the decision to let the patent lapse in Network Signatures “in accordance with standard policy, because there was no commercial interest in the invention.”[38] On the other hand, in Rembrandt, a “patent review board” convened to decide “which patents to abandon” and patent owner “decided to abandon [the patents]—namely, because it believed that they were not worth the fee.”[39] In light of the patent owner’s “other misconduct” in Rembrandt, the Federal Circuit concluded that “the district court reasonably could have decided that ‘intent to deceive the PTO [was] the single most reasonable inference able to be drawn from the evidence.’”[40]

At the district court level, 3D Medical Imaging Systems, LLC v. Visage  Imaging, Inc., provides guidance on circumstances under which a patent  owner may properly represent that a delay in payment of maintenance fees  was “unintentional.”[41] There, the patent owner, who had recently acquired the patent after a bankruptcy sell-off, petitioned the USPTO to revive the patent despite not knowing whether the former owner’s non-payment was unintentional, nor did it investigate the circumstances surrounding non-payment.[42] The district court had to determine whether the patent owner’s conduct amounted to inequitable conduct.[43] In doing so, the court rejected the patent owner’s assertion that Network Signatures immunized him from inequitable conduct because he used the USPTO’s standard form,[44] and explained that the key difference between Network Signatures and the instant case was that the patent owner in Network Signatures “at least knew of facts that informed his certification,” whereas the patent owner in 3D Medical  “had no personal knowledge of [the former patent owner’s] motivations for failing to pay the maintenance fee on time.”[45] Thus, the district court determined that the patent owner’s actions constituted inequitable conduct because “[t]he single most reasonable inference to be drawn from that evidence is that [the patent owner] made the misrepresentation with the specific intent to deceive the PTO.”[46] On that basis, the district court granted partial summary judgment in favor of the defendant on this issue.[47] The case settled shortly thereafter.[48]

The lesson to be learned from Network Signatures, Rembrandt, and 3D Medical is that representing the delayed payment as unintentional must be done with knowledge that the delay was, in fact, unintentional. If there is any evidence to the contrary, it is unlikely that the patent owner, if the patent is revived, will escape allegations of inequitable conduct.

Unpaid Maintenance Fees: What Should and Shouldn’t an Accused Infringer Do?

Should accused infringers encounter a patent that has lapsed at some point due to unpaid maintenance fees, there are a few strategies available to them before the USPTO and in district court.

Perhaps first and foremost, an accused infringer should investigate whether it can reasonably mount an inequitable conduct defense along the  lines of Rembrandt and/or 3D Medical, as discussed above.[49]  To prove inequitable conduct, the accused infringer must show that: (1) the patent owner  made misrepresentations within the petition for revival; (2) the misrepresentation was material; and (3) the single most reasonable inference based on the evidence showed a specific intent to deceive the PTO.[50] The defendant  must prove each element with clear and convincing evidence.[51]

In addition to that, a common tactic many accused infringers use when sued for patent infringement is to file an IPR petition. However, due to an increase in discretionary denials by the USPTO, which has decreased the number of instituted petitions overall,[52] IPR petitions arguably do not have the teeth they once had. For example, the “settled expectations” of the parties, which include the age of the patent, petitioner’s knowledge of the patent, examiner error, and a patent owner’s actions have influenced the increase in discretionary denials at the USPTO.[53] “Settled expectations” may favor the petitioner or the patent owner. For example, the USPTO Director has discretionarily denied petitions in favor of the patent owner on patents at least six years old or when the petitioner had knowledge of the patent.[54]

But despite the recent increase in discretionary denials, a petitioner sued for infringement of a patent that lapsed for non-payment of maintenance fees but was subsequently revived, may be successful in obtaining institution of an IPR proceeding by arguing that non-payment of the maintenance fee resulted in “settled expectations” that the patent would not be asserted against the petitioner. The Board has repeatedly declined to discretionarily deny IPR petitions when the petitioner demonstrated a “settled expectation” that the challenged patent would not be asserted.[55] Indeed, in Ford Motor Co. v. AutoConnect Holdings LLC, the USPTO Director stated that patent owner AutoConnect’s “own actions, or lack thereof, cut against any settled expectations that [AutoConnect] had developed as to at least one of the challenged patents” “[b]y failing to timely pay maintenance fees.”[56] AutoConnect had “allowed at least one of the challenged patents to lapse,”[57] and the Director emphasized that “[i]t is hard to square [AutoConnect’s] settled expectations argument” given that “at the time [AutoConnect] contacted Petitioner about its patent portfolio, one of the challenged patents had lapsed and was not enforceable” due to non-payment of the maintenance fee.[58]

In addition, an accused infringer may have intervening rights if it began making or using the claimed invention or took steps to begin using the claimed invention during the lapse period.[59] 35 U.S.C. § 41(c)(2) provides such rights. While there is a split among district courts, the majority view appears to be that an accused infringer may obtain intervening rights only if it began the allegedly infringing activity during the period of the lapse and in reliance of that lapse.[60] As a practical matter, however, courts have not yet found sufficient evidence of reliance, suggesting it is an uphill battle for accused infringers to establish it had intervening rights while the patent was in the public domain after failure to pay maintenance fees.[61]

Effects of Nonpayment on Ex Parte Reexamination Proceedings

Patent owners and accused infringers should also be wary of the potential effects non-payment of maintenance fees have on ex parte reexamination proceedings. Patent expiration affects not only the appropriate claim construction standard applied to the claims being reexamined, but also the ability of the patent owner to amend its claims.

During the initial prosecution of a patent, examiners scrutinize claims using the broadest reasonable interpretation (BRI) standard.[62] This is typically the same standard applied during reexamination of an unexpired patent.[63] The BRI standard is broader than the construction typically afforded to claims in issued patents using the framework set forth in Phillips v. AWH Corporation,[64] which interprets claims based on the plain meaning of claim terms in light of the intrinsic record.[65] The broader scope of BRI tends to make it easier to invalidate patents in reexamination proceedings. The Federal Circuit has explained that BRI is permissible during reexamination because patent owners have the ability to amend claims to narrow their scope, “negating any unfairness that may otherwise result from adopting the [broadest reasonable interpretation] standard.”[66] However, once a patent expires, patent owners may no longer make amendments to their claims.[67] Patent owners lose the opportunity to amend or adjust claims for which a substantial  new question of patentability has been found once their patent has expired.[68]  As a consequence, the Phillips standard applies to the reexamination of expired patents, meaning that it tends to be more difficult to invalidate lapsed or expired patents due to the narrower standard.[69]

This shifting claim construction standard has the potential to complicate a reexamination proceeding if a patent owner fails to pay a maintenance fee that comes due during the reexam. When that happens, the patent lapses and the patent owner cannot amend its claims.[70] The claims would then be subject to the narrower Phillips interpretation standard.[71] Conceptually, however, it is possible for a patent owner to revive a patent that lapsed during reexamination due to maintenance fee non-payment, and thereby regain the ability to amend the claims.[72] In that case, the patent would once again be subject to BRI.[73]

Parties who are considering pursuing an ex parte reexamination on a patent that has expired[74] due to non-payment of maintenance fees should consider addressing claim constructions under both the Phillips and BRI standards in the event the patent owner successfully revives the patent. Patent challengers should also be wary of adopting claim construction positions that could be seen as inconsistent with positions the challengers are taking in other forums, as the USPTO Director has recently denied or vacated several challenges at the PTAB when the petitioner offered claim construction positions that differed from those taken in district court proceedings.[75]The Director could use the same authority to deny or terminate reexamination proceedings should inconsistent claim construction positions have no adequate explanation for the inconsistency.[76]

Conclusion

Patent owners should prioritize timely maintenance fee payments. If,  however, a payment is missed unintentionally, there is a path to revival. But  revival may come with its own obstacles: different claim construction standards, intervening rights of others, and potential inequitable conduct allegations. Thus, failure to pay maintenance fees can have sobering effects for  patent owners and patent challengers alike and should not be overlooked.

Originally printed in the Chicago-Kent Journal of Intellectual Property. Reprinted with permission.

[1] 35 U.S.C. § 41(b)(1)(A)–(C).

[2] Ray v. Lehman, 55 F.3d 606, 608 (Fed. Cir. 1995).

[3] Ford Motor Co. v. AutoConnect Holdings LLC, IPR2025-01342, Paper 10 & IPR2025-01383, Paper 11 (P.T.A.B. Dec. 4, 2025).

[4] In re CSB-Sys. Int’l, Inc., 832 F.3d 1335, 1341 (Fed. Cir. 2016); see also Manual of Patent Examining Procedure § 2258.I.G (Rev. Jan. 2024).

[5] See Fonar Corp. v. Gen. Elec. Co., 107 F.3d 1543, 1554 (Fed. Cir. 1997). When a patent is reinstated after a lapse, parties who, during the lapse period, “made, purchased or used” goods that would infringe the reinstated patent are entitled to “continue the use of, or to sell to others” those goods “so made, purchased, or used.” 35 U.S.C. § 41(c)(2). “The second sentence of 35 U.S.C. § 41(c)(2) grants courts discretion to “‘provide for the continued manufacture, use, offer for sale, or sale of the [good] . . . to the extent and under such terms as the court deems equitable for the protection of investments made or business commenced’ during the lapse period.” Allied Tube & Conduit Corp. v. John Maneely Co., 125 F. Supp. 2d 987, 1003 (D. Ariz. 2000). These are equitable intervening rights. “The purpose of [this portion of] the statute is to protect investments which have been made in good faith reliance on some perceived infirmity in the original patent.” Id. at 1004 (quoting Thayer v. Nydigger, No. CIV 95–2004– AS, 1999 WL 372552, at *12 (D. Or. 1999) (quoting Halliburton Co. v. Western Co. of North Am., 10 U.S.P.Q.2d 1973, 1983 (W.D. Okla. 1988), aff’d, 935 F.2d 281 (Fed. Cir. 1991))).

[6] See, e.g., Network Signatures, Inc. v. State Farm Mut. Auto. Ins. Co., 731 F.3d 1239 (Fed. Cir. 2013); In re Rembrandt Techs. LP Pat. Litig., 899 F.3d 1254 (Fed. Cir. 2018).

[7] “The Director may accept the payment of any maintenance fee due on a patent after expiration of the patent if, upon petition, the delay in payment of the maintenance fee is shown … to have been unintentional.” 37 C.F.R. § 1.378(a).

[8] 35 U.S.C. § 41(b)(2).

[9] 37 C.F.R. § 1.17(m)(1)–(2).

[10] 35 U.S.C. § 41(c)(1); see also In re Rembrandt Techs., 899 F.3d at 1272.

[11] Whitewater W. Indus., Ltd. v. Pac. Surf Designs, Inc., 2018 WL 2979575, at *6 (S.D. Cal. June 8, 2018) (quoting MPEP § 2590); see also In re Rembrandt Techs., 899 F.3d at 1273.

[12] 37 C.F.R. § 1.378(b)(3).

[13] Procedures vary depending on when the patentee files the petition. If within two years of expiration, the patentee can simply file an E-Petition, which is automatically processed and immediately decided. See 2590 Acceptance of Delayed Payment of Maintenance Fee in Expired Patent to Reinstate Patent [R-Jan.2024]. Data released by the PTO suggests a patentee can expect their petition will be granted without further inquiry, but patentees should be aware that the PTO reserves the right to inquire into reasons for non-payment for any petition. Id. As of January 2026, in the past twelve months, the PTO received 1,961 E-Petitions to accept unintentional delayed payment of the maintenance fee. Since E- Petitions are automatically processed, the average pendency period was 0 days and the petitions were granted 100% of the time. United States Patent and Trademark Office, Petition Data Jan. 2026, Petition Data | Patents Dashboard | USPTO (last visited Mar. 11, 2026).

If more than two years have passed since the patent expired due to non-payment of maintenance fees, then the patentee must use the PTO/SB/66 form found on the PTO website to file a petition. United States Patent and Trademark Office, Forms for Patent Applications, www.uspto.gov/PatentForms (last visited Mar. 11, 2026). No E-Petitions are permitted when the patent has been expired for more than two years. As of January 2026, over the preceding 12 months, only 78% of non-E-Petitions were granted. The average pendency period for a non-E-Petition was 57 days. United States Patent and Trademark Office, Petition Data Jan. 2026, Petition Data | Patents Dashboard | USPTO (last visited Mar. 11, 2026). If the petition is granted, the patent is considered as not having expired at the end of the grace period. 35 U.S.C. § 41(c)(1). Patentees can appeal rejections to the Federal Circuit. See Ray, 55 F.3d at 607.

[14] 35 U.S.C. § 41(a)(7).

[15] See Clarification of the Practice for Requiring Additional Information in Petitions Filed in Patent Applications and Patents Based on Unintentional Delay, 85 Fed. Reg. 12222-24 (Mar. 2, 2020), Federal Register :: Clarification of the Practice for Requiring Additional Information in Petitions Filed in Patent Applications and Patents Based on Unintentional Delay.

[16] Id.

[17] Id.

[18] See id. Federal Register :: Clarification of the Practice for Requiring Additional Information in Petitions Filed in Patent Applications and Patents Based on Unintentional Delay.

[19] Network Signatures, 731 F.3d at 1239.

[20] Id. at 1240–41.

[21] Id. at 1241.

[22] Id. at 1241.

[23] Id. at 1241.

[24] Id. The patent owner later explained in the district court proceeding that maintenance fee payment decisions were made “once or twice a year, and that ‘if there is an expression of interest,’” the patent owner would pay the maintenance fee.

[25] Id. at 1242.

[26] Id. at 1243 (citing 37 C.F.R. § 1.378(c)(3)).

[27] Network Signatures, 731 F.3d at 1243 (“compliance with the standard PTO procedure for delayed payment” and “using the PTO form for delayed payment[] does not provide clear and convincing evidence of withholding of material information with intent to deceive”); see supra text accompanying note 2; In re Rembrandt Techs., 899 F.3d at 1275 (quoting Network Signatures, 731 F.3d at 1243).

[28] In re Rembrandt, 899 F.3d at 1274.

[29] Id. at 1261, 1273.

[30] Id. at 1273–74.

[31] See id.

[32] Three former employees of patent owner were involved in connection with the petition to the USPTO to revive the lapsed patents. The opinion does not distinguish between the individuals regarding who certified that the failure to pay fees was unintentional. Id. at 1261.

[33] Id. at 1274.

[34] Id. at 1261, 1275.

[35] Id. at 1274.

[36] See id. at 1273 (“It is clear, therefore, that the PTO would not have revived the patents if it had known that [patent owner] consciously allowed them to expire. . . . [Patent owner’s] alleged mistake of fact is no defense. It may be true that [patent owner’s] employees genuinely believed that a patent could be revived for years even after the six-month grace period for payment. But their decision not to make the payment still was intentional.”

[37] See id. at 1274–75.

[38] Id. at 1274.

[39] Id.

[40] Id. at 1275.

[41] 3D Med. Imaging Sys., LLC v. Visage Imaging, Inc., 228 F. Supp. 3d 1331, 1333 (N.D. Ga. 2017).

[42] Id. at 1333.

[43] Id.

[44] Id. at 1337.

[45] Id. Recent cases have agreed with this point, citing to 3D Medical for the proposition that claiming an entire period of delay was unintentional, without personal knowledge of that fact, was a misrepresentation to the PTO. See Swinford v. 360Booth Inc., No. 8:21-cv-02993, 2025 WL 2101837 at *14 (M.D. Fl. July 28, 2025) (currently on appeal at the Federal Circuit); see Weisner v. Google LLC, No. 20-cv- 2862, 2025 WL 3249033 at *36 (S.D.N.Y. Nov. 21, 2025) (magistrate judge recommendation) (district court judge “provisionally” agreed with the recommendation’s finding that the entire period of delay was not unintentional in Weisner v. Google LLC, No. 20-cv-2862, 2026 WL 121659 at *7 (S.D.N.Y. Jan. 15, 2026)).

[46] Id. at 1339.

[47] Id.

[48] 3D Med. Imaging Sys., LLC v. Visage Imaging, Inc., No. 2-14-cv-00267, Dkt. No. 91 (N.D. Ga. Apr. 26, 2017).

[49] Bringing a claim for ‘improper revival’ or the like is insufficient. See Ferguson Beauregard/Logic Controls, Div. of Dover Res., Inc. v. Mega Sys., LLC, 350 F.3d 1327, 1344 (Fed. Cir. 2003) (affirming district court’s decision declining to address alleged inequitable conduct issue because it was not raised as an inequitable conduct claim and inequitable conduct cannot be inferred from an improper revival claim).

[50] Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011); see also Biosonix, LLC v. Hydrowave, LLC, No. 4:16-cv-139, 2016 WL 9241284 (E.D.Tex., Aug. 15, 2016).

[51] Network Signatures, 731 F.3d at 1242.

[52] While the institution rate by petition in Fiscal Year 2024 was 68%, the institution rate decreased to 50% for Fiscal Year 2025. From October 2025 through February 2026, the institution rate by petition was 37%. See United States Patent and Trademark Office, PTAB Trial Statistics February 2026, Trial Stats February 2026 (last visited March 29, 2026).

[53] See Memorandum from Coke Morgan Stewart, Acting Under Sec’y of Com. for Intell. Prop. And Acting Dir. of the USPTO (March 26, 2025) Memorandum – Interim Processess for PTAB workload management

[54] Intel Corp. v. Proxense LLC, IPR2025-00327, Paper 12 at 2–3 (PTAB June 26, 2025); iRhythm Techs., Inc. v. Welch Allyn, Inc., IPR2025-00363, Paper 10 at 3 (PTAB June 6, 2025).

[55] Home Depot U.S.A., Inc. v. H2 Intellect LLC, IPR2025-00480, Paper 11 (P.T.A.B. Sept. 4, 2025); Ford Motor Co., IPR2025-01342, Paper 10 & IPR2025-01383, Paper

[56] Ford Motor Co., IPR2025-01342, Paper 10.

[57] Id.

[58] Id.

[59] See Fonar Corp., 107 F.3d at 1554.

[60] See, e.g., Cardiac Pacemakers, Inc. v. St. Jude Med., Inc., No. IP 96-1718-C-H/G, 2001 WL 483973, at *3 (S.D. Ind. May 2, 2001); Thayer v. Nydigger, No. CIV. 95-2004-AS, 1999 WL 372552 (D. Or. Apr. 15, 1999); Aero Products Intl, Inc. v. Intex Recreation Corp., No. 02 C 2590, 2003 WL 22723017 (N.D. Ill. Nov. 18, 2003). Challengers should be aware that because the Federal Circuit has not explicitly held reliance is required, arguments against it may be viable. For example, the District of Minnesota noted in Geospan Corp. v. Pictometry Int’l Corp. that neither the text of the statute, nor the legislative history require reliance and thus the Fonar passage suggesting reliance is required could be mere non-binding dictum. 2009 WL 10678281, at *3.

[61] See, e.g., Utecht v. Olson, 84 F. Supp. 2d 1039, 1043 (D. Minn. 2000) (rejecting affirmative defense based on intervening rights under section 41(c)(2) for failure to meet the reliance requirement); Allied Tube & Conduit Corp. v. John Maneely Co., 125 F. Supp. 2d 987, 1005, 1007 (D. Ariz. 2000) (finding patent challenger had no intervening rights because it could not establish good-faith reliance).

[62] See In re Am. Acad. of Sci. Tech. Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004).

[63] See id.; see also CSB-Sys., 832 F.3d at 1340.

[64] See Facebook, Inc. v. Pragmatus AV, LLC, 582 F. App’x 864, 869 (Fed. Cir. 2014) (nonprecedential) (“The broadest reasonable interpretation of a claim term may be the same as or broader than the construction of a term under the Phillips standard. But it cannot be narrower.”).

[65] See Phillips v. AWH Corp., 415 F.3d 1303, 1312–15 (Fed. Cir. 2005) (en banc).

[66] CSB-Sys., 832 F.3d at 1341.

[67] See 37 C.F.R. § 1.530(j) (“No amendment may be proposed for entry in an expired patent. Moreover, no amendment, other than the cancellation of claims, will be incorporated into the patent by a certificate issued after the expiration of the patent.”); see also CSB-Sys., 832 F.3d at 1342.

[68] See CSB-Sys., 832 F.3d at 1342.

[69] See CSB-System, 832 F.3d at 1341–42; In re Rambus, Inc., 753 F.3d 1253, 1256 (Fed. Cir. 2014); see also In re Express Mobile, Inc., No. 2023-1076, 2024 WL 2747287, at *5 (Fed. Cir. May 29, 2024).

[70] See Rambus, 753 F.3d at 1256 (applying Phillips standard because the patent had expired during the appeal before the Patent Trial and Appeal Board); Facebook, 582 F. App’x at 868–69 (applying Phillips standard when patent expired after the Board’s reexamination decision pending appeal to the Federal Circuit); see also Manual of Patent Examining Procedure § 2250.III (9th ed. Rev. 01.2024).

[71]See CSB-Sys., 832 F.3d at 1340.

[72] See 37 C.F.R. § 1.378(a) (“If the Director accepts payment of the maintenance fee upon petition, the patent shall be considered as not having expired”).

[73] See CSB-Sys., 832 F.3d at 1341.

[74] Reexamination proceedings may be initiated against expired patents because patent owners maintain certain rights after the patent expires that could be resolved by an ex parte reexamination. See In re Gesture Tech. Partners, LLC, 160 F.4th 1317, 1322 (Fed. Cir. 2025); see also 37 C.F.R. § 1.510(a) (“Any person may, at any time during the period of enforceability of a patent, file a request for an ex parte reexamination.”).

[75] Revvo Techs., Inc. v. Cerebrum Sensor Techs, Inc., IPR2025-00632, Paper 20 at 4–5 (P.T.A.B. Nov. 3, 2025) (precedential); Sun Pharms. Indus. Inc. v. Nivagen Pharms., Inc., IPR2025-00893, Paper 18 at 3 (P.T.A.B. Sept. 19, 2025) (informative); Tesla, Inc. v. Intellectual Ventures II LLC, IPR2025- 00340, Paper 18 at 3 (P.T.A.B. Nov. 5, 2025) (informative).

[76] See 35 U.S.C. § 325(d) (giving the Director authority to discretionarily terminate proceedings under “chapter 30” of Title 35, which includes ex parte reexaminations).