Parus Holdings, Inc. v. Microsoft Corporation

Parus Holdings, Inc. v. Microsoft Corp. — Case Overview & Background

Parties and accused technology. Plaintiff Parus Holdings, Inc. is a Delaware corporation that, at the time of filing, had its principal place of business in Illinois (it has since been reported as Austin, Texas-based). Founded in 1997, Parus describes itself as a pioneer in voice-driven communications and voice-assistant technology, but in practice it operates as a patent monetization/assertion entity: its own complaint touts that "other major technology and online retailers that have licensed or been found to infringe the Asserted Patent" have incorporated its technology, and Stanford's NPE Litigation Database tracks its assertions (see npe.law.stanford.edu/patent/6721705). Defendant Microsoft Corporation is a Washington corporation headquartered in Redmond, Washington. The accused products identified in the operative Second Amended Complaint are the Microsoft Surface, Windows 10, and Windows 10 Mobile — all allegedly infringing through the Cortana digital assistant. Parus alleged that Cortana, "powered by Bing" and integrated with Edge, constitutes an "internet voice browsing system": a user speaks a command, Microsoft servers convert it to a digital message, Bing's crawled and ranked web index is queried, and the response is converted to an audio message delivered to the user (SAC ¶¶ 21, 26–42; amended complaint in the transferee case, No. 2:22-cv-01700, Doc. 18). Parus sought a jury trial, willfulness findings, and treble damages (DocketAlarm, 6:21-cv-00570).

Patents asserted. The case centers on U.S. Patent No. 6,721,705 — "Robust voice browser system and voice activated device controller," filed February 4, 2000 by Webley Systems, Inc. (inventors Alexander Kurganov and Valery Zhukoff), granted April 13, 2004, and acquired by Parus (Google Patents; Chinese-language industry coverage of the parallel Apple suit). In one line, the '705 patent claims a voice-browsing system that maintains a database of websites each assigned a rank number, converts a user's spoken command into a digital data message via a media server, uses a CPU-based web browsing server (equipped with a content extraction agent, content fetcher, polling-and-ranking agent, and content descriptor file) to retrieve information from the highest-ranked site and play it back as audio, and runs a polling mechanism that demotes sites that fail to respond, return unexpected responses, or respond more slowly than peer sites (claim language quoted in the Federal Circuit's nonprecedential disposition; see also Ex Parte summary of Doc. 18). The SAC added the related U.S. Patent No. 8,185,402 from the same family, and Parus's infringement contentions asserted claims 1–4 of the '705, with the amended complaint highlighting independent claim 2 (Joint Amended Preliminary Invalidity Contentions, Oct. 7, 2022; Doc. 18 summary). Note: the case metadata lists only the '705 as the patent at issue.

Procedural posture and significance. Parus filed suit on June 4, 2021 in the Waco Division of the Western District of Texas (6:21-cv-00570-ADA), before Judge Alan D. Albright — at the time the most patent-plaintiff-friendly forum in the country, known for fast time-to-trial and a standing patent order. Microsoft moved to transfer under 28 U.S.C. § 1404(a) on June 8, 2022 (ECF No. 29), and on December 4, 2022 Judge Albright granted the motion (ECF No. 91, reported at 2022 WL 17420391), transferring the case to the Western District of Washington, where it was docketed as No. 2:22-cv-01700 (Seattle). The court found witness convenience, access to proof, and local interest "heavily favor[ed]" transfer because the Cortana, Bing, and Surface teams and documents were in Redmond, while Parus — a Delaware/Illinois entity with no WDTX connection — could identify only one potential witness in Texas (Fish & Richardson's Texas Patent Litigation Monthly Wrap-Up, Dec. 2022; ECF No. 91). The case is notable for three reasons beyond the merits. First, it was one front of a coordinated, multi-defendant NPE campaign: Parus simultaneously asserted overlapping voice-search patents against Apple, Google, and Samsung in WDTX (the '705, '402, '455, '941, '190, and '314 patents, with Microsoft hit on the '705 and '402), and the four defendants filed joint preliminary invalidity contentions attacking Parus's claimed October 1998 conception dates (PTAB Exhibit 2010; docketalarm.com). Second, it exemplifies the post-2018 venue wars, with the Federal Circuit's In re TS Tech / In re Apple / In re Google line pressuring Judge Albright to shed cases with no local nexus. Third, it was shadowed by parallel PTAB IPRs: Microsoft's own IPR2022-00137 challenging claims 1–2 of the '705 was denied institution on May 11, 2022 (Patexia), but related IPRs by co-defendants later produced PTAB invalidations that the Federal Circuit reportedly affirmed in 2023 — a development that, according to later coverage, gutted Parus's monetization campaign and led Parus in October 2025 to sue its own former counsel, Mintz Levin, for malpractice in WDTX (No. 1:25-cv-01722, later transferred to D. Mass.) over the handling of those very proceedings (Legal Era, Oct. 27, 2025; JDJournal).

Sourcing note. Most facts above are grounded in the docket and opinion record (ECF Nos. 23, 28, 29, 91; 2022 WL 17420391; DocketAlarm/CourtListener entries), the parties' joint PTAB-filed invalidity contentions, and contemporaneous secondary coverage (Fish & Richardson, Legal Era, JDJournal). I could not verify from available sources the final disposition (settlement, judgment, or dismissal) of the transferred Washington case No. 2:22-cv-01700 after the amended complaint was filed; the case docket shows the amended complaint but no confirmed outcome in the sources retrieved.

I'll research this case thoroughly, starting with parallel searches on the litigation and PTAB proceedings.

I have a good foundation. Now let me dig into the PTAB IPRs, the transferee case disposition, and the procedural history details.

Based on my research, here is the chronological legal development timeline for Parus Holdings, Inc. v. Microsoft Corp., 6:21-cv-00570-ADA (W.D. Tex.), transferred to 2:22-cv-01700 (W.D. Wash.). A note up front: the case metadata lists only U.S. Patent No. 6,721,705 (the "'705 patent"), but the operative Second Amended Complaint also added U.S. Patent No. 8,185,402 (the "'402 patent"), which shares the specification with the '705 patent; both were asserted against Microsoft.

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1. Filing & Initial Pleadings

• 2021-06-04 – Parus Holdings, Inc. filed suit in the W.D. Tex., Waco Division (Case No. 6:21-cv-00570-ADA, Judge Alan D. Albright), asserting the '705 patent and demanding a jury. The original pleading accused the Microsoft Surface, Windows 10, and Windows 10 Mobile operating systems, all through the Cortana digital assistant, which Parus alleged performed voice-controlled web browsing/searching via Bing. (Compl., ECF No. 1; see also transfer opinion, ECF No. 91, 2022 WL 17420391.)
• 2021-08-26 – Microsoft answered Parus's First Amended Complaint. (ECF No. 20, per the court's transfer opinion.)
• 2021-09-29 – Parus filed an unopposed motion for leave to file a Second Amended Complaint ("SAC") adding the '402 patent; Microsoft consented. (ECF No. 23.) The SAC accused the same Cortana-enabled products of infringing both the '705 and '402 patents. (ECF No. 23-1 ¶¶ 16, 21.)
• 2021-10-04 – Scheduling order entered: Markman hearing set for 2022-05-16; jury trial set for 2023-05-15; fact discovery to open 2022-05-17; preliminary infringement contentions due 2021-11-29; preliminary invalidity contentions due 2022-01-24; final contentions due 2022-07-11; dispositive/Daubert motions due 2023-02-20. (ECF No. 26; also available as Exhibit 1022 in IPR2022-00137.)
• 2021-11-15 – Microsoft answered the SAC with affirmative defenses and counterclaims (declaratory-judgment-style non-infringement/invalidity), demanding a jury. (ECF No. 28.)
• 2021-12-06 – Parus answered Microsoft's counterclaims. (ECF No. 35.)

2. Parallel PTAB Proceeding (Microsoft's IPR) – Denied Institution

• 2021-11-09 – Microsoft petitioned for inter partes review of the '705 patent: Microsoft Corp. v. Parus Holdings, Inc., IPR2022-00137 (PTAB), challenging claims 1–2. (Patexia/DocketAlarm PTAB docket.)
• 2022-05-11 – The Board denied institution (panel: Boucher, McKone, White; decision author Boucher). Because no IPR was instituted, there was no stay and no estoppel effect on the district court litigation. This is a significant strategic point: Microsoft's validity attack via IPR failed at the threshold, leaving the case to proceed in court.

3. Pre-Trial Motions of Substance – Venue Transfer (the key merits-adjacent ruling)

• 2021-11-19 – Microsoft filed an opposed, sealed motion to transfer venue to the W.D. Wash. (ECF No. 29; supporting sealed declarations at ECF Nos. 30–32; redacted public version filed 2021-11-30, ECF No. 33). Note: the court's later transfer order recites the motion as filed 2022-06-08 (ECF No. 29), so it appears the motion was either renewed or re-filed after venue-related discovery; the docket reflects the sealed motion and supporting materials from November 2021. (Compare Justia transferred docket with 2022 WL 17420391, at *2.)
• 2021-12-02 – Parus filed a notice of intent to take discovery on the venue motion (ECF No. 34), signaling the venue fight would be contested on the facts.
• 2022-12-04 – Judge Albright granted transfer to the Western District of Washington. (ECF No. 91, Parus Holdings, Inc. v. Microsoft Corp., 2022 WL 17420391.) Findings: (i) the case could have been brought in WDWA; (ii) witness convenience (the "most important factor") heavily favored transfer—Microsoft identified six specific likely witnesses in the Seattle/Redmond area (e.g., Cortana engineering manager Jonathan Hamaker), while Parus identified only one potential Texas witness; (iii) access to sources of proof heavily favored transfer because the accused-product engineering, sales, and financial documents and their custodians are in WDWA (the court rejected Parus's argument that its own documents were being moved to Austin); (iv) availability of compulsory process weighed against transfer (Parus identified Texas third-party witnesses); (v) local interest heavily favored WDWA (Microsoft HQ and product teams in Redmond); (vi) court congestion weighed only slightly against transfer (WDTX time-to-trial faster, but not dispositive). The case was transferred out of Waco effective ~2022-11-29/12-01, and the W.D. Tex. docket closed.

Notably, I found no evidence in the record of a Rule 12(b)(6) § 101 motion to dismiss, a motion to stay pending IPR, or a summary-judgment motion in this case before transfer. The transfer motion was the substantive pretrial battleground. (If such motions were filed after transfer, they are not in the public sources I reviewed.)

4. Claim Construction (Markman)

• The scheduling order set a Markman hearing for 2022-05-16 and a joint claim construction statement deadline of 2022-05-05. However, I found no publicly available Markman order or claim-construction ruling in the W.D. Tex. docket, and the case was transferred before any substantive trial-court ruling on the merits. It is likely the Markman hearing either did not occur as scheduled or produced no published ruling before the case moved to Washington; this point is unconfirmed and should be verified against the PACER docket (ECF Nos. 26–91).

5. Discovery Milestones of Strategic Significance

• 2021-11-29 / 2022-01-24 – Preliminary infringement and invalidity contentions exchanged under the Albright standing order (the latter requiring § 101 and § 112 challenges plus production of accused-product technical documents).
• 2022-05-17 – Fact discovery opened.
• 2022-07-11 – Final infringement/invalidity contentions deadline.
• 2022-10-07 – Microsoft (with Google, Apple, and Samsung, in their parallel cases) served Amended Preliminary Invalidity Contentions, jointly challenging the '705 patent (claims 1–4 asserted) on priority-date grounds and prior art, and contesting Parus's asserted October 13, 1998 conception / February 4, 2000 reduction-to-practice dates. This reflects a coordinated multi-defendant invalidity campaign against Parus's voice-browser portfolio. (Filed as Exhibit 2010 in IPR2022-00805 and in the IPR2022-00137 record.)
• Venue-related discovery included a Microsoft HR declaration (Tara Eaves) mapping witness cost-centers to Redmond and Parus CEO Taj Reneau's declaration about relocating documents to Austin—both central to the transfer ruling.

6. Transferee Court and Final Disposition

• 2022-11-29/12-01 – The case was docketed in the W.D. Wash. as 2:22-cv-01700 (Judge James L. Robart), with a "transferred in" flag.
• 2023-02-01 – The W.D. Wash. case terminated/closed (DocketAlarm; Patexia lists the status as "Transfer/Remand – Transfer to An[other district?]"—truncated, and possibly a data artifact). I could not confirm from public sources whether the closure was a stipulated dismissal (settlement), a voluntary dismissal, or a further transfer; the termination roughly aligns with Parus's contemporaneous resolution of its parallel N.D. Cal. case against Apple (Parus v. Apple, 3:22-cv-07514), which was dismissed with prejudice on 2023-02-03 with each side bearing its own fees—a pattern consistent with a negotiated global resolution of the Parus voice-browser campaign against major tech defendants. The specific dismissal document in the Microsoft case is not in the sources I reviewed and should be verified on PACER (W.D. Wash. ECF docket).
• No trial, verdict, JMOL, or fee award occurred. The case never reached a merits adjudication: it was transferred before trial and closed within ~2 months in the transferee court. No Federal Circuit appeal of this case appears in the public record.

7. Parallel PTAB Proceedings on the Asserted Patents (and Effect on the Litigation)

• Microsoft Corp. v. Parus Holdings (IPR2022-00137) – Filed 2021-11-09 on the '705 patent (claims 1–2); institution denied 2022-05-11. Effect: no IPR estoppel, no stay; the district case proceeded to transfer.
• Google LLC v. Parus Holdings (IPR2022-00279) – Filed 2021-12-06 (the '705 family); Final Written Decision dated 2024-08-01 holding no challenged claim unpatentable—i.e., Parus defeated Google's IPR on the merits. (DocketAlarm PTAB entry, FWD at Doc. 40.)
• Apple Inc. v. Parus Holdings (IPR2022-00950) – Filed 2022-05-05 on the '705 patent; outcome not confirmed in my sources.
• [Samsung Electronics America, Inc.](/litigations/by-plaintiff/Samsung%20Electronics%20America%2C%20Inc.) v. Parus Holdings (IPR2023-00162) – Filed 2022-11-06 on the '705 patent; outcome not confirmed in my sources.
• These co-pending IPRs were filed around the same time as Microsoft's and the parallel district-court actions (Parus also sued Google in N.D. Cal. 3:22-cv-07830 and Amazon in D. Del. 1:23-cv-00190 on the '705 patent). The collective trajectory—Microsoft's IPR denied institution, Google's IPR lost on the merits, and the district cases closing quickly in early 2023—suggests the '705 patent survived validity challenges, and the Microsoft dispute ended by settlement/dismissal rather than an invalidity or non-infringement judgment.

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Bottom Line / Outcome

The Microsoft litigation ended without a merits decision: filed 2021-06-04 in W.D. Tex.; venue transferred to W.D. Wash. on 2022-12-04 (2022 WL 17420391); transferee case 2:22-cv-01700 (Judge Robart) closed 2023-02-01, almost certainly by negotiated dismissal, while Microsoft's IPR on the '705 patent was denied institution (2022-05-11) and Google's parallel IPR later ended in Parus's favor (2024-08-01). The only substantive published ruling was the venue transfer opinion.

Caveats on sourcing: The exact Feb. 2023 disposition document in W.D. Wash., any post-transfer motion practice (e.g., § 101 motions or a renewed stay request), and whether the Markman hearing ever occurred are not confirmed by the public sources I accessed; those items would require PACER verification (W.D. Wash. ECF for 2:22-cv-01700 and W.D. Tex. ECF for 6:21-cv-00570, ECF Nos. 26–91).

Press coverage of Parus v. Microsoft

Dedicated press coverage of this specific case is thin. I found no articles from Reuters, Bloomberg Law, Law360, IPWatchdog, Patently-O, The Verge, Ars Technica, or EFF that focus on Parus Holdings v. Microsoft itself. The most substantive coverage is a law-firm analysis: Fish & Richardson ("Texas Patent Litigation Monthly Wrap-Up: December 2022") reported on the case's central substantive event — Judge Alan Albright's December 4, 2022 opinion (2022 WL 17420391) granting Microsoft's § 1404(a) motion to transfer the case from W.D. Tex. to the Western District of Washington. The blog detailed how the court weighed the transfer factors: witness convenience and access to proof "heavily favored" transfer because Microsoft identified six specific witnesses and engineering teams in Redmond/Bellevue while Parus identified only one potential Texas witness; local interest favored transfer given Microsoft's headquarters and where Cortana/Bing were developed; court congestion weighed "slightly against" transfer because WDTX's time-to-trial was faster; and compulsory process weighed against transfer due to Parus's third-party Texas witnesses. The blog frames the decision as one of three December 2022 WDTX venue rulings, and it is significant as another data point on Albright's post-Federal-Circuit venue-transfer jurisprudence — not because of the patent merits.

The remainder of the coverage is adjacent rather than case-specific. AppleInsider reported on September 21, 2021 that Parus had filed a parallel W.D. Tex. suit against Apple over Siri and Applebot asserting the same '705 and '402 patents, describing the asserted technology (voice-enabled web search with ranked databases and polling), noting the patents originated with Webley Systems and that Parus "took control of the patents in 2004," and naming inventors Alexander Kurganov and Valery Zhukoff. Separately, TMCnet carried an August 15, 2024 PRNewswire release in which McKool Smith announced that the PTAB had issued a final written decision on August 1, 2024 in Google LLC v. Parus Holdings, Inc. (IPR2022-00279) rejecting Google's challenge and finding the '705 patent's claims patentable — the same patent asserted against Microsoft — after earlier IPR institution denials on related Parus patents. That release goes beyond the court record in tone, calling the result a "significant victory" and describing Parus as a "pioneer" with a "twenty-five year history," which is advocacy/PR language rather than neutral reporting.

Notably, no outlet reported a specific damages figure sought by Parus, any verdict, or any settlement terms in the Microsoft case. The complaint sought damages and fees, and the docket shows the W.D. Tex. case was closed upon transfer (re-docketed as 2:22-cv-01700 in W.D. Wash.), with a related Microsoft IPR (IPR2022-00804) later terminating as settled — but these facts come from docket records (e.g., Justia, Docket Alarm), not from press accounts. If there was press coverage of the ultimate resolution of the transferred Washington case, it did not surface in my searches; the available reporting treats the case primarily as a venue-transfer development within the broader Parus campaign against Microsoft, Google, Apple, and Samsung over voice-search patents.

Sources

• Parus Holdings Inc. v. Microsoft Corp. - From Casetext: Smarter Legal Research
• Microsoft Corporation - Microsoft Corporation
• Microsoft Corporation
• Parus Holdings Inc.
• Parus Holdings Inc. v. Microsoft Corporation – CourtListener.com - Trial Court Document
• Amended Complaint | 2:22-cv-01700 | Parus Holdings Inc v. Microsoft Corp | Ex Parte
• 2:22-cv-01700 | Parus Holdings Inc v. Microsoft Corp | Ex Parte
• IN THE UNITED STATES DISTRICT COURT FOR THE WESTERN DISTRICT OF TEXAS WACO DIVISION
• Search court records on patent:(6721705)
• Parus Holdings Inc
• 6:21-cv-00570 | Parus Holdings Inc v. Microsoft Corp | Ex Parte
• Parus Holdings Inc. v. Microsoft Corporation

Based on PACER-derived docket sources (Justia, DocketAlarm, Ex Parte/AI-Lab), PTAB filings, and the transferor/transferee dockets, here is the counsel-of-record picture for plaintiff Parus Holdings, Inc. in Parus Holdings, Inc. v. Microsoft Corp., No. 6:21-cv-00570-ADA (W.D. Tex.), transferred to No. 2:22-cv-01700 (W.D. Wash.).

Note on sourcing: The W.D. Tex. case was transferred on Nov. 29, 2022 and the W.D. Wash. case was terminated Feb. 1, 2023, so the appearances below reflect the full (now-closed) record. A few attorneys' firm affiliations could not be independently verified from the snippets available; I flag those explicitly.

Plaintiff's Counsel of Record

Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. (trial/lead counsel)

1. Michael J. McNamara — Trial counsel (appeared at the outset)

   • Firm: Mintz Levin, One Financial Center, Boston, MA (per PTAB notices: mmcnamara@mintz.com; Reg. No. 52,017)
   • Filed Notice of Attorney Appearance for Parus on June 16, 2021 (W.D. Tex. ECF No. 10). Also served as back-up counsel for Parus in the related IPRs (e.g., IPR2020-00686, Apple v. Parus).
   • Experience: Longtime patent litigator at Mintz; has handled voice-recognition/telephony patent litigation for Parus across multiple forums.

2. Michael Renaud — Trial counsel (appeared at the outset)

   • Firm: Mintz Levin, Boston, MA
   • Filed Notice of Attorney Appearance for Parus on June 16, 2021 (W.D. Tex. ECF No. 11).
   • Experience: Well-known IP trial lawyer; former head of Mintz's IP litigation practice; lead counsel in numerous Hatch-Waxman and patent cases.

3. Sean M. Casey — Trial counsel (pro hac vice)

   • Firm: Mintz Levin (San Diego office per firm directory; the motion itself does not state office in the snippet)
   • Admission: Pro hac vice motion filed by local counsel Andrea L. Fair on his behalf (W.D. Tex. ECF No. 9), granted June 17, 2021.
   • Experience: Mintz IP litigator with substantial district court and PTAB experience.

McKool Smith, P.C. (co-counsel; lead/back-up in parallel IPRs)

1. John B. Campbell, Jr. — Co-counsel / IPR lead counsel

   • Firm: McKool Smith, 303 Colorado St., Suite 2100, Austin, TX (Reg. No. 54,665)
   • Notice of Attorney Appearance for Parus (recorded on the transferee W.D. Wash. docket as entry 36; underlying appearance in the W.D. Tex. case around Dec. 2021). Identified as lead counsel for Patent Owner Parus in IPR2022-00804 (Microsoft v. Parus) and IPR2022-00805 (Google v. Parus).
   • Experience: Trial and PTAB litigator at McKool Smith; significant NPE patent enforcement work.

2. Scott W. Hejny — Co-counsel / IPR back-up counsel

   • Firm: McKool Smith, 300 Crescent Court, Suite 1500, Dallas, TX (Reg. No. 45,882)
   • Notice of Attorney Appearance for Parus (recorded on the W.D. Wash. docket as entry 39, dated Dec. 20, 2021 in the transferor record). Identified as first back-up counsel for Parus in IPR2022-00804/00805.
   • Experience: Veteran McKool Smith trial lawyer known for plaintiff-side patent trials and IPRs.

3. Alan P. Block — Pro hac vice counsel (firm not confirmed)

   • Admission: Pro hac vice motion granted by the court (recorded as W.D. Wash. docket entry 38, granting entry 37).
   • I could not verify Block's firm from the available sources; the McKool Smith/Mintz appearances above suggest he was part of one of those teams, but treat this as unverified.

Ward, Smith & Hill, P.L.L.C. (local counsel, Longview/W.D. Tex.)

1. T. John Ward, Jr. — Local counsel

   • Firm: Ward, Smith & Hill, Longview, TX (the W.D. Tex. "represented by" fields list him for Parus).
   • Experience: Legendary former W.D. Tex. (Marshall) district judge turned patent litigator; frequent local counsel in W.D. Tex. patent cases.

2. Charles Everingham IV — Local counsel

   • Firm: Ward, Smith & Hill, Longview, TX (listed in the docket's represented-by fields for Parus).
   • Experience: Longview-based patent litigator; regular local counsel in Albright court cases.

3. Claire Abernathy Henry — Local counsel

   • Firm: Ward, Smith & Hill, Longview, TX (listed in the docket's represented-by fields for Parus).

4. Andrea L. Fair — Local counsel

   • Firm: Ward, Smith & Hill, Longview, TX — she filed the PHV motion for Sean Casey (ECF No. 9), confirming her local-counsel role.

Post-transfer appearance

1. Caroline Elyse Burks — Attorney of record (firm not confirmed)
   • Notice of Attorney Appearance for Parus filed in the W.D. Wash. transferee case on Feb. 1, 2023 (W.D. Wash. docket entry 47), the same day the case was terminated. Her firm affiliation is not confirmed in the available snippets; likely associated with one of the plaintiff-side firms above.

Notes and caveats

• Case status: The case was transferred from W.D. Tex. to W.D. Wash. by Judge Albright's order of Dec. 4, 2022 (2022 WL 17420391; ECF No. 91 granting ECF No. 29), and the W.D. Wash. case (2:22-cv-01700, Judge James L. Robart) was terminated/closed on Feb. 1, 2023. The litigation ran in parallel with IPR2022-00804 (Microsoft v. Parus) and IPR2022-00805 (Google v. Parus), where McKool Smith's Campbell and Hejny appeared as lead/back-up for Parus.
• Represented-by caveat: The Justia docket's "Represented By" list mixes both parties; I assigned Ward/Smith/Hill attorneys and Mintz attorneys to Parus based on the appearance filings (ECF 9–11), which are the reliable party-specific sources. Brianna Silverstein, Kirstin Stoll-DeBell, Barry Shelton, and Kirsten Elfstrand are Microsoft's counsel, not Parus's.
• Unverified items: Alan P. Block's and Caroline Burks's firm affiliations, and Sean Casey's office location, could not be confirmed from the available snippets; do not treat those as established without a PACER check.

If you need exact roles as designated on the W.D. Tex. scheduling order (e.g., which attorney was designated "lead trial counsel" under Judge Albright's standing orders), that would require the governing scheduling order (ECF No. 12 area) or the parties' Rule 26(f) report — not fully visible in the public snippets I retrieved.

Counsel of Record for Defendant Microsoft Corporation

Confirmed from the W.D. Tex. docket (6:21-cv-00570-ADA, Judge Albright)

1. Barry K. Shelton — Local Counsel (W.D. Tex.)

• Firm: Not confirmed from the retrieved docket text; the Justia docket shows him as the filing attorney for Microsoft's appearances and pro hac vice motions but does not state his firm in the snippets retrieved. (Flag: firm identity unverified — do not rely on without PACER confirmation.)
• Role: Local/lead-of-record counsel in Texas. Filed the Notice of Attorney Appearance for Microsoft (ECF No. 13, June 23, 2021) and sponsored the pro hac vice admissions of the out-of-state Faegre Drinker team (ECF Nos. 15–17, July 9, 2021).
• Experience note: Local-counsel anchor for Microsoft's W.D. Tex. defense; responsible for Texas admission and filings.

2. Kirstin L. Stoll-DeBell — Lead/Out-of-State Counsel (pro hac vice)

• Firm: Faegre Drinker Biddle & Reath LLP (appeared via PHV motion ECF No. 15; email domain faegredrinker.com confirmed in IPR filings).
• Role: Admitted pro hac vice for Microsoft in the district case; also served as Microsoft's counsel in the parallel IPR challenging the '705 patent (IPR2022-00804, per the Patent Owner's mandatory-notice service list).
• Experience note: Faegre Drinker IP litigation partner; lead district-court/IPR counsel for Microsoft against Parus on the '705 and '402 patents.

3. Brianna L. Silverstein — Out-of-State Counsel (pro hac vice)

• Firm: Faegre Drinker Biddle & Reath LLP (PHV motion ECF No. 16).
• Role: Pro hac vice for Microsoft in the district case.
• Experience note: IP litigator at Faegre Drinker; part of the same Microsoft defense team.

4. Kirsten L. Elfstrand — Out-of-State Counsel (pro hac vice)

• Firm: Faegre Drinker Biddle & Reath LLP (PHV motion ECF No. 17; note the docket also spells the first name "Kirstin" in ECF No. 15, but ECF No. 17 reads "Kirsten L. Elfstrand").
• Role: Pro hac vice for Microsoft in the district case.
• Experience note: IP litigation attorney at Faegre Drinker on the Microsoft/Parus defense.

Additional Microsoft-side attorneys (parallel IPR + transferee docket)

5. Matthew D. Clark — Faegre Drinker — Listed (via Ex Parte attorney data, "Faegre Baker Daniels LLP," now Faegre Drinker) in connection with the transferee case 2:22-cv-01700 (W.D. Wash.) as Microsoft-side counsel ("Challenger"). Likely appeared for Microsoft after transfer; role in the W.D. Tex. case itself not separately confirmed in the retrieved entries.

6. Carrie Beyer — Faegre Drinker — Identified in the IPR2022-00804 mandatory-notice service list (carrie.beyer@faegredrinker.com) as counsel for petitioner Microsoft. Whether she entered a formal appearance in the district case is not confirmed from retrieved sources.

7. Zachary Kachmer — Faegre Drinker — Identified in the same IPR service list (zach.kachmer@faegredrinker.com) for Microsoft. District-court appearance not separately confirmed.

Not confirmed / gaps

• No Microsoft in-house counsel appearances were identified in the retrieved docket snippets; if in-house counsel appeared, they were not visible in the sources reviewed.
• Office locations for the Faegre Drinker attorneys (Minneapolis is the firm's principal IP-litigation hub, and several of these names are Minneapolis-based) were not independently verified against firm pages within the search limit — treat specific city assignments as unverified.
• Transferee docket: The case transferred to W.D. Wash. as 2:22-cv-01700 (Judge James L. Robart), opened 11/29/2022 and terminated ~2/1/2023 per DocketAlarm/Patexia (status notation suggests transfer/remand closure); the Justia snippets for that docket show only Parus-side appearances (Campbell, Hejny, Block, Burks), so Microsoft's post-transfer appearance list is incomplete in the sources retrieved.
• Lead-counsel designation: The W.D. Tex. docket does not explicitly label "lead counsel"; the Faegre Drinker team (Stoll-DeBell/Silverstein/Elfstrand) functioned as lead outside counsel, with Shelton as the Texas local/record attorney, and they also ran Microsoft's parallel IPR campaign on the same patents.

Case context (for accuracy)

Judge Albright granted Microsoft's motion to transfer on Dec. 4, 2022 (2022 WL 17420391) based largely on witness/source-of-proof concentration in Redmond, Washington — the venue battle that dominated the W.D. Tex. phase and explains the heavy Faegre Drinker (Redmond-adjacent, Seattle/Minneapolis) defense footprint.