Microsoft Corporation et al. v. Lemko Corporation

Case Overview & Background: Microsoft Corp. & Affirmed Networks, Inc. v. Lemko Corp. (IPR2023-00531)

Parties and technology. This matter is an inter partes review (IPR2023-00531) at the PTAB — the metadata's "plaintiffs" are actually the petitioners, and the underlying patent-infringement case is Lemko Corp. v. Microsoft Corp. & Affirmed Networks, Inc., No. 3:22-cv-00363-L-BT (N.D. Tex., Dallas Div.). Lemko Corporation (Schaumburg, Illinois; founded 2004) is a small, self-described pioneer of Network Functions Virtualization (NFV) and Mobile Edge Computing who built and sold software-based "distributed mobile architecture" (DMA) mobile-core products (its "Node1"/network-in-a-box line) for rural and remote deployments (Alaska, Northern Canada, Africa); it styles itself as a practicing operating company but is pursuing a serial assertion campaign against large telecom/cloud adopters (it sued Microsoft/Affirmed in February 2022 and AT&T in the Eastern District of Texas in March 2025). Petitioners are Microsoft and Affirmed Networks, which Microsoft acquired in 2020 (Lemko's own press release inaccurately dates the acquisition to 2022); Affirmed supplies virtualized Evolved Packet Core (vEPC)/mobile-core software now integrated into Microsoft's Azure for Operators platform. In the district court case, Lemko's "live pleading" accuses a collection of Microsoft/Affirmed edge-and-core products — Affirmed Mobile Core, Mobile Content Cloud (MCC), Affirmed Cloud Edge (ACE), UnityCloud, Affirmed Private Network Service (APNS), vProbe, and Azure Stack Edge (ASE) servers — of providing private LTE/5G and MEC networks with decentralized, NFV-based core functionality, data/voice routing, and interworking with the Internet and carrier cellular networks. The focal patent here is U.S. Patent No. 7,855,988 ("System, Method, and Device for Routing Calls Using a Distributed Mobile Architecture"; inventor Shaowei Pan; filed July 14, 2008; issued Dec. 21, 2010), whose claims cover routing calls between distributed, software-based mobile-network servers via "DMA gateways": a first gateway receives and stores (in a "home DMA register") communications information about a network served by a second gateway, then routes a call/data communication to a target device by relaying it through a DMA-gateway network (claims 1, 3–9, and 20 were challenged). Lemko's district-court complaint asserts a portfolio of DMA-family patents beyond the '988 (including a '409 patent), so this IPR covers only one patent-in-suit.

Procedural posture and parallel proceedings. Lemko sued Microsoft and Affirmed on February 14, 2022, in the Northern District of Texas (Dallas Division) before Judge Sam A. Lindsay, with a magistrate judge (docket designation "-BT"; the magistrate's name is not confirmed in the sources retrieved). The district court has twice addressed 12(b)(6) motions to dismiss: on August 13, 2024, Judge Lindsay adopted a magistrate's report and dismissed Lemko's direct and indirect infringement claims without prejudice but allowed one final amendment (Doc. 79), and on June 4, 2025, he adopted a further report (Doc. 90), dismissing contributory infringement with prejudice while otherwise denying the motion (Doc. 94) — Lemko touted that denial in an April 15, 2025 press release. In parallel, Microsoft and Affirmed filed this IPR petition exactly one year after the complaint — on February 14, 2023, at the edge of the 35 U.S.C. § 315(b) one-year bar — part of a coordinated IPR family against Lemko's DMA patents (including IPR2023-00529 over U.S. Patent No. 7,653,414, argued jointly; a companion petition, IPR2023-00530, was denied institution). The Board (Judges Frances L. Ippolito, Brian D. Range, and Scott Raevsky) instituted review on September 25, 2023 (Paper 8) on a single ground — anticipation of all challenged claims by U.S. Patent Application Publication 2007/0021120 ("Flore") — heard oral argument on July 11, 2024, and issued a Final Written Decision on September 10, 2024 (Paper 31) finding claims 1, 3–9, and 20 unpatentable by a preponderance of the evidence, with Judge Raevsky authoring. Petitioners were represented by Winston & Strawn (Robert Kang, Barry Shelton, Michael Rueckheim; expert James Proctor); Lemko by Kramer Levin (James Hannah, Aaron Frankel, Jeffrey Price, Jenna Fuller, Jeffrey Eng; expert Dr. Todor Cooklev of Purdue). Lemko appealed on September 16, 2024; the Federal Circuit (No. 2024-2336) heard argument and, on April 10, 2026, affirmed in a nonprecedential Rule 36 per curiam judgment (Hughes and Stoll, Circuit Judges; Seeborg, Chief District Judge) — so although the docket metadata still lists the IPR as "appealed," the appeal has now concluded against Lemko.

Why the case matters. First, it is a textbook example of the PTAB/district-court interplay: Lemko's infringement case was pending before Judge Lindsay in N.D. Tex. while the Board's invalidation of all challenged '988 claims ran in parallel, and the affirmance gives Microsoft/Affirmed estoppel leverage (35 U.S.C. § 315(e)(2)) to simplify or dispose of the '988 portions of the Dallas suit. Second, the substantive fight is significant for the NFV/MEC industry: Lemko claims it conceived of virtualized, distributed mobile cores and demonstrated them to carriers (including a 2013 meeting with AT&T Labs and the author of AT&T's 2012 NFV white paper) years before the industry's ETSI/NFV shift, and it is now asserting those early-2000s-vintage patents against the cloud giants and carriers that adopted edge computing and virtualized cores (Microsoft's Azure Stack Edge/Azure Operator Nexus; later AT&T). The IPR turned on hotly contested claim construction — whether "distributed mobile architecture" requires genuinely distributed, peer-to-peer call-routing functionality versus merely being "part of a broader network," and whether "communications information" must identify a device subscribed to a network accessible via the second gateway — with Lemko arguing on appeal that the Board misconstrued "communications information" and never resolved the dispositive "distributed" dispute, arguments the Federal Circuit rejected summarily. The case thus illustrates both the risk to a pioneering small holder enforcing broad, early NFV claims against later industry adoption and the effectiveness of coordinated, single-reference (Flore) IPR attacks, while Unified Patents' tracking confirms the NPE-style pattern: a large operating company (Microsoft) facing an operating-company/patent-holder (Lemko) in serial IPR and district-court skirmishes across the DMA patent family.

Scope note and orientation

The case metadata you supplied — Microsoft Corp. et al. v. Lemko Corp., IPR2023-00531 — is the PTAB inter partes review of U.S. Patent No. 7,855,988, not the infringement suit itself. The underlying patent infringement litigation is Lemko Corp. v. Microsoft Corp. and Affirmed Networks, Inc., No. 3:22-cv-00363-L-BT (N.D. Tex., Dallas Div.), before Judge Sam A. Lindsay with magistrate-judge referral (initials "BT"). The IPR is a parallel proceeding that Microsoft/Affirmed brought against the '988 patent (among others) as a validity challenge to that litigation. Below is the chronological development of both tracks, with the district-court litigation as the primary subject.

A transparency note up front: I could not pull the full PACER docket (entry-level detail for many district-court filings — answers, discovery orders, stay motions, Markman proceedings — is not in the public web-accessible sources I could reach within the step limit). I flag sourcing confidence for each item.

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I. District court: filing and initial pleadings (N.D. Tex.)

• 2022-02-14 — Complaint filed. Lemko sued Microsoft and Affirmed Networks in the Northern District of Texas, Dallas Division, No. 3:22-cv-00363-L-BT, with a jury demand. (Source: Lemko Corp. press release, Apr. 15, 2025, lemkocorp.com — states the suit was filed Feb. 14, 2022; Patexia case docket confirms "Complaint with jury demand" as the opening document.) Microsoft acquired Affirmed Networks in March 2022, after suit was filed.
• The complaint asserted a portfolio of Lemko "Distributed Mobile Architecture" (DMA) patents. By the time of the operative amended pleadings, the case involved eight patents: the '763, '414, '988, '409, '111, '980, '478, and '931 patents. The '988 patent (U.S. 7,855,988, "System, Method, and Device for Routing Calls Using a Distributed Mobile Architecture") is the one at issue in IPR2023-00531. (Source: ECF No. 77 at 4–8, discussed in gov.uscourts.txnd.359096.77.0.pdf via archive.org, filed 2024-07-29, which summarizes the asserted patents from the Original Complaint (ECF No. 1) and Amended Complaint (ECF No. 59).)
• Lemko's infringement theories target Microsoft's/Affirmed's virtualized mobile-packet-core / edge networking products (e.g., Affirmed's virtualized packet core integrated into Microsoft's Azure Operator Nexus platform). (Source: Lemko press release, Apr. 15, 2025.)
• Answers/counterclaims: I could not verify from public sources whether Microsoft's answer asserted declaratory-judgment counterclaims of non-infringement/invalidity or the exact date. Unverified — treat as a gap.

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II. Parallel PTAB proceedings on the asserted patents (the IPR track)

Microsoft and Affirmed (as co-petitioners) filed multiple IPRs against Lemko's asserted patents. Two are confirmed in detail:

• IPR2023-00531 ('988 patent) and IPR2023-00529 ('414 patent) — petitions filed 2023-02-14 (exactly one year after the district-court complaint; the petition cites service of the N.D. Tex. complaint on both defendants as Exs. 1007–1008). (Sources: DocketAlarm track dockets; PTAB FWD copy at bannerwitcoff.com; Ex. 1007/1008 descriptions.)
• 2023-09-25/26 — Institution. The Board granted institution in both IPRs, finding a reasonable likelihood that the challenged claims were unpatentable. For IPR2023-00531, institution decision is dated 2023-09-25; the parallel '414 institution decision (IPR2023-00529) was entered 2023-09-26. (Sources: ipverse.greyb.com; DocketAlarm; PTAB Decision – Granting Institution, IPR2023-00529, Paper 11.)
• 2023-11-17 — Director Review denied. Lemko sought Director review of the institution decisions. Director Kathi Vidal recused; Deputy Director Derrick Brent denied the requests in a combined order (Paper 14 in both cases). (Source: DocketAlarm, IPR2023-00531 Paper 14.)
• 2023-12-21 — Patent Owner Response filed (Paper 15), with expert declaration of Dr. Todor Cooklev (Ex. 2021) and other exhibits. (Source: DocketAlarm docket entries.)
• 2024-02-22 — Joint stipulation to modify schedule (Paper 16). (Source: DocketAlarm.)
• 2024-03-11 — Deposition of Dr. Cooklev (Petitioner's expert, James Proctor, had earlier submitted Ex. 1003 declaration). (Source: Ex. 1014 transcript reference in Petitioners' Reply.)
• 2024-03-28 — Petitioners' Reply (Paper 21) — key disputed issue was claim construction of "distributed mobile architecture" and "communications information." (Source: DocketAlarm Paper 21 PDF.)
• 2024-05-09 — Patent Owner Sur-Reply (Paper 22). (Source: DocketAlarm.)
• 2024-06-20 — Board order setting oral argument, with the Board sua sponte introducing dictionary definitions of "distributed architecture"/"distributed processing" (Exs. 3002–3003) for the parties to address. (Source: Lemko's Fed. Cir. opening brief, Appx420-21, 2643-47, via PTACTS download.)
• 2024-07-11 — Oral hearing. Joint hearing for IPR2023-00529 and IPR2023-00531 before APJs Ippolito, Range, and Raevsky. (Source: PTAB hearing transcript, entered 2024-08-19.)
• 2024-09-10 — Final Written Decision (IPR2023-00531, Paper 31). The Board held claims 1, 3–9, and 20 of the '988 patent unpatentable as anticipated by U.S. Patent Application Publication 2007/0021120 ("Flore") under 35 U.S.C. § 102. The Board rejected Lemko's proposed construction of "communications information" and declined to adopt a restrictive construction of "distributed." The parallel IPR2023-00529 ('414 patent) also terminated with a FWD on 2024-09-10. (Source: FWD PDF at bannerwitcoff.com; DocketAlarm Paper 31; case metadata.)
• 2024-09-16 — Lemko's Notice of Appeal from the IPR2023-00531 FWD (Paper 32). (Source: DocketAlarm; Lemko's Fed. Cir. brief at Appx525-28.)

Federal Circuit appeal of the '988 IPR — now decided:

• The appeal was docketed as Lemko Corp. v. Microsoft Corp., No. 2024-2336 (Fed. Cir.). Lemko's opening brief (2025-01-29) argued the Board (1) misconstrued "communications information" and (2) failed to resolve the parties' dispute over the meaning of "distributed." (Source: Lemko opening brief, PTACTS download, signed Jan. 29, 2025.) Counsel on appeal: Kramer Levin (by then "Herbert Smith Freehills Kramer (US) LLP") for Lemko; Winston & Strawn/King & Spalding for Microsoft.
• 2026-04-10 — Federal Circuit affirmed. A per curiam panel (Circuit Judges Hughes and Stoll, Chief District Judge Seeborg sitting by designation) entered a Rule 36 nonprecedential judgment AFFIRMING the PTAB's Final Written Decision in IPR2023-00531. (Source: CAFC Rule 36 Judgment, No. 2024-2336, entered 2026-04-10, cafc.uscourts.gov PDF.)

Net effect on the '988 patent: the challenged claims are finally unpatentable, subject to no further review (no petition for certiorari identified as of the search date).

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III. District court: pre-trial motions and Rule 12(b)(6) litigation

This is the most heavily documented phase of the infringement suit in accessible public sources.

• First motion to dismiss (pleading-stage). Defendants moved to dismiss Lemko's initial pleading under Fed. R. Civ. P. 12(b)(6), asserting pleading deficiencies in Lemko's infringement allegations. The court (through the magistrate judge's recommendation) allowed Lemko to amend — but expressly warned that this would be the final opportunity to cure pleading deficiencies. (Source: ECF No. 94 (2025-06-04 Order), quoting the court's prior ruling.)
• 2024 — Amended Complaint (ECF No. 59), then a further amended complaint (ECF No. 63). Lemko's live pleading asserted the eight-patent portfolio (see Doc. 77 summary). (Source: ECF No. 77, filed 2024-07-29, archive.org copy.)
• 2024-07-29 — Defendants' motion to dismiss the amended complaint (ECF No. 77, 23 pp.). The motion argued, inter alia, that Lemko's infringement allegations — including as to direct, induced, and contributory infringement against Microsoft's and Affirmed's accused products — were inadequately pleaded. (Source: archive.org copy of ECF No. 77.)
• 2025-04-10 — Magistrate Judge's Findings, Conclusions and Recommendation (ECF No. 90) on Defendants' renewed Motion to Dismiss the Second Amended Complaint (ECF No. 85). The Report recommended granting dismissal of Lemko's contributory patent infringement claims (§ 271(c)) and denying the motion in all other respects (i.e., direct and induced infringement claims adequately pleaded). No objections were filed. (Source: ECF No. 94.)
• 2025-06-04 — District court order (ECF No. 94). Judge Lindsay accepted the Report and Recommendation, granting the motion to dismiss as to contributory infringement — dismissed with prejudice (no further amendment allowed), and denying it otherwise. Direct and induced infringement claims on the surviving patents therefore remain pending. (Source: Justia — ECF No. 94; Lemko press release of Apr. 15, 2025, announced the earlier denial of the motion to dismiss Lemko's direct and indirect infringement claims, consistent with the Report.)

Items I could not verify from open sources (gaps): whether defendants ever moved to transfer venue or to stay the district case pending the IPRs (common practice here, but unconfirmed); the existence/timing of any Markman claim-construction order in the N.D. Tex. case; and substantive discovery milestones (beyond the IPR depositions noted above). Nothing I found indicates the case has reached trial, judgment, or settlement — as of the last confirmable district-court event (2025-06-04), the case is active on Lemko's surviving direct- and induced-infringement theories.

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IV. Strategic significance and interplay between the tracks

• Estoppel / validity posture. With the FWDs finding the '988 (and '414) challenged claims unpatentable and the Federal Circuit's 2026-04-10 affirmance of the '988 decision, Lemko is estopped from asserting the invalidated '988 claims in the N.D. Tex. case (35 U.S.C. § 315(e)(2); see also the IPR's statutory estoppel as to grounds raised or reasonably available). This substantially narrows the district-court case, which originally spanned eight patents.
• Filing-date strategy. The IPR petitions were filed 2023-02-14 — exactly one year after the complaint — consistent with the § 315(b) one-year bar and signaling that Microsoft/Affirmed intended the PTAB as the primary validity battleground.
• Claim-construction overlap. The dispositive IPR disputes — the meaning of "distributed mobile architecture" and "communications information" — were the same terms that would control infringement in the district case. The Board's constructions (plain and ordinary meaning; rejecting Lemko's narrowing "distributed functionality" reading) and the Federal Circuit's affirmance will constrain any later district-court construction of the surviving claims.
• Contributory-infringement dismissal. The 2025-06-04 order eliminated Lemko's § 271(c) theory with prejudice, while leaving direct and induced infringement alive — a partial but meaningful winnowing for Microsoft/Affirmed at the pleading stage.

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V. Bottom line / present posture

• '988 patent (IPR2023-00531): PTAB FWD (2024-09-10) — claims 1, 3–9, and 20 unpatentable; Federal Circuit affirmed (2026-04-10, No. 2024-2336, Rule 36). The '988 claims are invalidated with finality.
• District court (3:22-cv-00363-L-BT): active as of the last confirmed order (2025-06-04); direct- and induced-infringement claims survive on the remaining asserted patents; contributory infringement dismissed with prejudice; no trial, verdict, JMOL, or final judgment identified; no settlement reported.
• Principal sources: PTAB FWD and papers (PTACTS/DocketAlarm/bannerwitcoff.com), CAFC Rule 36 Judgment 2024-2336 (cafc.uscourts.gov, 2026-04-10), N.D. Tex. ECF Nos. 77, 90, 94 (Justia/archive.org), and Lemko Corp.'s 2025-04-15 press release. CourtListener's docket page for 3:22-cv-00363 exists but entry-level detail (answers, discovery, Markman, stay motions) was not accessible within my search limit — those items remain unverified rather than confirmed absent.

Threshold caveat: this is an IPR, not a patent infringement case — and the caption is reversed in the underlying litigation

The docket you've identified — IPR2023-00531, Microsoft Corporation et al. v. Lemko Corporation (P.T.A.B.) — is an inter partes review of U.S. Patent No. 7,855,988, not a patent infringement suit. There is no district-court infringement action captioned "Microsoft v. Lemko." The related infringement suit is Lemko Corporation v. Microsoft Corporation and Affirmed Networks, Inc., No. 3:22-cv-00363-L-BT (N.D. Tex.), where Lemko is the plaintiff (patent owner) and Microsoft/Affirmed are the defendants. The '988 patent was asserted against Microsoft/Affirmed in that N.D. Tex. case (see Lemko's Fed. Cir. brief and the IPR petition's exhibits, Ex. 1007–1008). Microsoft and Affirmed Networks were the petitioners at the PTAB and are the appellees in the Federal Circuit appeal (No. 2024-2336, affirmed by Rule 36 judgment on April 10, 2026).

So I've set out counsel below under two readings of "plaintiff(s)," so you can pick the right mapping. Nothing is sealed that would obscure counsel appearances; all names below come from public PTAB papers, the N.D. Tex. docket, or the Federal Circuit judgment.

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Reading 1 — The Microsoft/Affirmed side (petitioners/appellees; i.e., the side captioned first in your case metadata, and the "defendants" in the actual infringement suit)

In the IPR (petitioners):

• Robert N. Kang — Lead counsel for petitioners (USPTO Reg. No. 59,609). Winston & Strawn LLP, 101 California Street, San Francisco, CA 94111. Designated lead in the petitioners' Power of Attorney (Paper 1, Feb. 14, 2023) and still signing as lead counsel as late as the Feb. 26, 2024 updated exhibit list (DocketAlarm IPR2023-00531). Note: the July 11, 2024 hearing transcript refers to "lead counsel for IPR2023-00531, Rob King" — I could not verify any attorney named "Rob King"; all papers designate Robert N. Kang as lead, so this appears to be a court-reporter rendition of "Rob Kang" (unverified, flagging for your diligence).
• Barry K. Shelton — Back-up counsel (Reg. No. 76,273). Winston & Strawn LLP, 2121 N. Pearl St., Suite 900, Dallas, TX 75201. Also appeared for Microsoft/Affirmed in the N.D. Tex. infringement case (N.D. Tex. Dkt. 23, notice of appearance).
• Michael R. Rueckheim — Back-up counsel / pro hac vice (admitted under 37 C.F.R. § 42.10 by unopposed motion, Paper 18, Feb. 26, 2024). Winston & Strawn LLP, 255 Shoreline Dr., Suite 520, Redwood City, CA at the time; he argued at the PTAB oral hearing on July 11, 2024. Declared substantial district-court patent litigation experience (multiple infringement cases, trials, and claim-construction hearings) in his PHV declaration (Ex. 1013).

In the Federal Circuit appeal (appellees Microsoft/Affirmed):

• Matthew R. McCullough — argued for appellees; Winston & Strawn LLP, Redwood City, CA (per the April 10, 2026 Rule 36 judgment in No. 2024-2336).
• Michael R. Rueckheim — on the appellees' brief, by then at King & Spalding LLP, San Francisco, CA (same Rule 36 judgment).

In the N.D. Tex. infringement case (defendants Microsoft/Affirmed):

• Barry K. Shelton and Michael R. Rueckheim (Winston & Strawn) filed notices of appearance (N.D. Tex. Dkts. 22–23), and Kelly C. Hunsaker appeared as counsel for the defendants (motion to dismiss, Dkt. 24; pro hac vice admission granted, Dkt. 21). I could not verify Hunsaker's firm from the sources retrieved — do not assume affiliation without checking PACER.

In-house: No Microsoft or Affirmed in-house counsel appeared of record in the documents I located; the PTAB representation was outside counsel throughout.

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Reading 2 — The actual plaintiff in the underlying patent infringement case (Lemko Corporation)

If you meant the true plaintiff in the N.D. Tex. infringement action, that is Lemko Corporation, represented by Kramer Levin Naftalis & Frankel LLP (now Herbert Smith Freehills Kramer (US) LLP after the firm combination):

• Paul J. Andre, Lisa Kobialka, and James R. Hannah — Kramer Levin, 333 Twin Dolphin Dr., Suite 700, Redwood Shores, CA 94065 (N.D. Tex. PHV admissions, Dkts. 17–19; also Lemko's PTAB counsel — Hannah argued the '988 IPR).
• Aaron M. Frankel — Kramer Levin (Redwood Shores and New York, 1177 Avenue of the Americas); argued Lemko's appeal at the Federal Circuit (listed as Herbert Smith Freehills Kramer (US) LLP, New York).
• Also on the appeal/PTAB filings: Jeffrey H. Price, Jeffrey Eng, and Jenna Fuller (New York).
• In the N.D. Tex. case, filings also carry attorney Jon Hyland on Lemko's behalf (e.g., Dkt. 31) — likely Texas local counsel, but his firm wasn't confirmed in my search.

Relevant experience notes: Andre, Kobialka, Hannah, and Frankel are well-known IP litigators who have handled major patent trials and Federal Circuit appeals; Frankel argued the IPR appeal (No. 2024-2336), which the Federal Circuit affirmed under Rule 36 on April 10, 2026, upholding the PTAB's finding that claims 1, 3–9, and 20 of the '988 patent were unpatentable.

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Bottom line

• If you need the Microsoft/Affirmed "plaintiff-side" counsel as captioned in your case record: Robert N. Kang (lead, Winston & Strawn SF), Barry K. Shelton (Winston & Strawn Dallas), Michael R. Rueckheim (Winston & Strawn Redwood City, later King & Spalding SF), and Matthew R. McCullough (Winston & Strawn Redwood City, appeal).
• If you need the plaintiff in the actual patent infringement case (Lemko v. Microsoft, N.D. Tex.): Lemko's Kramer Levin team (Andre, Kobialka, Hannah, Frankel, Price, Eng, Fuller) plus Texas filer Jon Hyland.

Sources: PTAB Power of Attorney and exhibit list (DocketAlarm IPR2023-00531, Papers 1, 18, 19); PTAB hearing transcript of July 11, 2024 (DocketAlarm); Lemko's Federal Circuit appeal brief (Jan. 29, 2025, via ptacts.uspto.gov); Fed. Cir. Rule 36 judgment, No. 2024-2336 (April 10, 2026, cafc.uscourts.gov); N.D. Tex. docket via Justia/DocketAlarm (3:22-cv-00363-L-BT).

Preliminary clarification on posture

The case in your metadata — IPR2023-00531, Microsoft Corp. et al. v. Lemko Corp. (PTAB) — is an inter partes review, not a district-court patent infringement action. In the IPR, Microsoft and Affirmed Networks are the petitioners and Lemko Corporation is the patent owner/respondent (the "Defendant" in the case metadata). Lemko's '988 patent is asserted against Microsoft/Affirmed in the parallel district case, Lemko Corp. v. Microsoft Corp. et al., No. 3:22-cv-00363-L-BT (N.D. Tex.), where the party roles are reversed (Lemko is plaintiff; Microsoft and Affirmed are the accused infringers/defendants). Counsel of record for the Lemko side is the same Kramer Levin team across all three fora, as detailed below.

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Counsel of record for Lemko Corporation (patent owner / "defendant" per metadata)

All PTAB designations below are confirmed by the service lists and Board filings in IPR2023-00531 (e.g., Patent Owner's deposition notice, Paper 13, Nov. 15, 2023; Petitioners' PHV motion, Paper 18; Petitioners' Updated Exhibit List, Paper 19; and the PTAB Notice of Filing Date, Paper 6, Mar. 31, 2023, which lists the patent owner's counsel emails). The Federal Circuit brief in the appeal (No. 2024-2336) is signed by the same team. Firm note: Kramer Levin Naftalis & Frankel LLP merged with Herbert Smith Freehills; by the time of the Federal Circuit affirmance (April 10, 2026), the firm is styled Herbert Smith Freehills Kramer (US) LLP.

PTAB IPR2023-00531 — designated counsel of record

1. James R. Hannah — Lead Counsel for Patent Owner (USPTO Reg. No. 56,369)

   • Firm/Location: Kramer Levin Naftalis & Frankel LLP (now Herbert Smith Freehills Kramer (US) LLP), 333 Twin Dolphin Drive, Suite 700, Redwood Shores, CA 94065.
   • Note: Registered practitioner leading Kramer Levin's Lemko PTAB defense across the coordinated IPR2023-00529/00531 proceedings; appeared for Lemko at the July 11, 2024 oral hearing and on the Federal Circuit appeal team.

2. Aaron M. Frankel — Back-up Counsel (Reg. No. 52,913)

   • Firm/Location: Kramer Levin Naftalis & Frankel LLP (now Herbert Smith Freehills Kramer (US) LLP), 1177 Avenue of the Americas, New York, NY 10036.
   • Note: Signed Lemko's Federal Circuit opening brief and argued the appeal (No. 2024-2336) before the Federal Circuit; also listed in Lemko's public update as district-court counsel in the N.D. Tex. action.

3. Jeffrey H. Price — Back-up Counsel (Reg. No. 69,141)

   • Firm/Location: Kramer Levin, New York, NY.
   • Note: Filed Lemko's Director Review requests (Oct. 10, 2023) in IPR2023-00529/00531 challenging the institution decisions.

4. Jenna Fuller — Back-up Counsel (Reg. No. 74,212)

   • Firm/Location: Kramer Levin, Redwood Shores, CA.
   • Note: PTAB practice attorney on Lemko's IPR team; also on the Federal Circuit appeal caption.

5. Jeffrey Eng — Back-up Counsel (Reg. No. 63,189)

   • Firm/Location: Kramer Levin, New York, NY.
   • Note: IP litigator on Lemko's IPR and Federal Circuit appellate team.

Related district-court action (Lemko v. Microsoft, N.D. Tex.) and Federal Circuit appeal

The following Kramer Levin attorneys are of record for Lemko in the parallel infringement case and the appeal, though not among the registered lead/back-up designees in the IPR itself:

1. Paul J. Andre

   • Firm/Location: Kramer Levin, Redwood Shores, CA.
   • Note: Veteran patent trial lawyer; named in Lemko's April 15, 2025 public update as district-court counsel and on the Federal Circuit brief for Lemko.

2. Lisa Kobialka

   • Firm/Location: Kramer Levin, Redwood Shores, CA.
   • Note: Kramer Levin IP partner; district-court and Federal Circuit counsel for Lemko per the appellate filings and Lemko's public update.

In-house / local counsel: No Lemko in-house attorney or separate local counsel appears on the PTAB record; Lemko (Schaumburg, IL) is represented solely by the Kramer Levin team above. No filings appear sealed that would hide additional counsel.

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If you meant Microsoft/Affirmed Networks (the defendants in Lemko's N.D. Tex. infringement suit)

For completeness — counsel of record for Microsoft and Affirmed Networks in the IPR and the appeal are Winston & Strawn LLP: Robert N. Kang (lead, San Francisco), Barry K. Shelton (Dallas), Michael R. Rueckheim (Redwood City/Central District; later moved to King & Spalding), and on appeal Matthew R. McCullough (Winston & Strawn, Redwood City) argued for the appellees.

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Key sources

• PTAB Papers in IPR2023-00531 (DocketAlarm): Paper 6 (Mar. 31, 2023), Paper 13 (Nov. 15, 2023), Papers 18–19 (Feb. 26, 2024) — counsel lists and service lists.
• Lemko press release, "Update – Lemko Corporation Patent Litigation against Microsoft and Affirmed Networks" (Apr. 15, 2025) — naming Andre, Kobialka, Hannah, Frankel; noting N.D. Tex. denial of Microsoft's motion to dismiss.
• Federal Circuit, Lemko Corp. v. Microsoft Corp., Appeal No. 2024-2336: Lemko's brief (signed Jan. 29, 2025) and Rule 36 judgment affirming the PTAB's Final Written Decision (entered April 10, 2026), listing Herbert Smith Freehills Kramer (US) LLP attorneys.