Sonos, Inc. v. D&M Holdings Inc. d/b/a THE D+M GROUP et al.

Sonos, Inc., an American audio equipment manufacturer renowned for its wireless multi-room sound systems, smart speakers, soundbars, and headphones, initiated patent infringement litigation against D&M Holdings Inc., D&M Holdings U.S. Inc., and Denon Electronics (USA), LLC. D&M Holdings Inc., formed by the merger of Denon and Marantz, is a Japanese company that designs, manufactures, and sells audio, video, and media equipment globally. Denon Electronics (USA), LLC, a subsidiary of D&M Holdings, specifically markets audio equipment, including its HEOS wireless music systems, AV receivers, and headphones, which were the allegedly infringing products at the core of this dispute.

The litigation, filed in the U.S. District Court for the District of Delaware under case number 1:14-cv-01330, involved a portfolio of Sonos patents, with U.S. Patent No. 7,571,014 initially specified in the case metadata. Patent 7,571,014 generally describes a method and apparatus for controlling multimedia players in a multi-zone system, enabling different audio content to be played simultaneously in various rooms or zones. Other patents subject to a key claim construction ruling by Judge Richard G. Andrews included U.S. Patent Nos. 8,588,949 (methods for adjusting volume levels in a multi-zone system via user interfaces), 9,042,556 (shaping audio output, referred to as an "orientation patent"), 9,195,258 (synchronizing operations among independently clocked digital data processing devices for audio playback), 9,202,509 (controlling and grouping in a multi-zone media system), and 9,219,959 (multi-channel pairing in a media system for enhanced audio). Additionally, U.S. Patent Nos. 8,843,224, 8,938,312, 8,938,637, 9,213,357, and design patent D559,197 (related to an ornamental design of a button strip for a controller) were also part of the claim construction proceedings.

The District of Delaware is a significant venue for patent litigation due to a high concentration of corporate incorporations in the state, which establishes venue for many defendants, particularly after the Supreme Court's TC Heartland decision. The court is also known for its experienced judiciary in patent law, well-defined local rules, and predictable case management, making it an attractive forum for patent plaintiffs. The case concluded in 2018 via a confidential settlement, resulting in a dismissal with prejudice. Notable aspects of the litigation included a ruling by Federal Circuit Judge William Bryson, sitting by designation, which clarified the application of "absolute intervening rights" to method claims, providing important precedent on this defense. Furthermore, a damages expert report from Sonos was struck for failing to properly apportion damages according to the entire market value rule, highlighting a critical aspect of patent damages analysis. This case also sits within the broader context of Sonos's active patent enforcement strategy against competitors in the wireless audio market.

The patent infringement litigation Sonos, Inc. v. D&M Holdings Inc. et al. (1:14-cv-01330) in the U.S. District Court for the District of Delaware, involving U.S. Patent No. 7,571,014 among others, was terminated in 2018 following a confidential settlement.

Here is a chronological overview of the key legal developments and outcome:

• Filing & Initial Pleadings:

  • 2014-10-21: Sonos, Inc. filed its initial complaint, alleging infringement of four patents (D.I. 1).
  • Sonos subsequently amended its complaint multiple times, ultimately asserting a total of twelve patents (D.I. 6, 31, 102).
  • 2015-03-09 (approx.): D&M Holdings Inc. filed an answer to Sonos's Second Amended Complaint (D.I. 31), likely including counterclaims, as indicated by a reference in a later PTAB document.

• Pre-trial Motions of Substance:

  • 2017-03-13: The District Court denied Defendants' Partial Motion for Judgment on the Pleadings, which argued that four of the asserted patents, including U.S. Patent No. 7,571,014, were directed to ineligible subject matter under 35 U.S.C. § 101.
  • 2017-08-24: The Court denied Defendants' Motions for Summary Judgment of no direct and no indirect infringement (D.I. 298, 301), finding disputed issues of material fact.
  • 2017-12-07: The Court denied Sonos's motion for leave to submit a second supplemental expert report on damages. The Court had previously struck the expert's reasonable royalty analysis for failing to properly apportion damages, emphasizing that damages must be tied to the accused features rather than the entire market value of the product.

• Claim Construction (Markman) Outcomes:

  • 2016-12-14: The Court held oral argument on claim construction.
  • 2017-01-12: Judge Richard G. Andrews issued a Memorandum Opinion providing claim construction for multiple disputed terms across several patents, including U.S. Patent No. 7,571,014. The opinion requested supplemental briefing for four specific terms.
  • A subsequent opinion further construed these four terms after receiving supplemental briefing.

• Discovery Milestones with Strategic Significance:

  • While specific discovery milestones are not extensively detailed in publicly available summaries without direct PACER access, the denial of Sonos's supplemental expert report on damages (D.I. 457) on December 7, 2017, highlights a significant development in the damages phase of discovery, leading to a crucial ruling on apportionment.

• Trial Events, Verdict, and Post-Trial Motions:

  • 2017-12-11: A bellwether trial commenced for some of the asserted patents, including U.S. Patent No. 7,571,014, 8,588,949, and 9,195,258.
  • Late 2017: Sonos secured a decisive victory in the bellwether trial. The jury found D&M Holdings had willfully infringed Sonos's patents and awarded Sonos nearly $2 million in damages.
  • Following the verdict, Sonos filed post-trial motions seeking enhanced damages, a permanent injunction against infringing products, attorney fees, supplemental damages for ongoing infringement, and pre-judgment and post-judgment interest.

• Settlement, Dismissal, Judgment, or Appeal:

  • 2018-05-18: The case was terminated. The parties reached a confidential settlement agreement, resulting in the filing of a dismissal with prejudice (D.I. 565). The Court retained jurisdiction to enforce the terms of the confidential agreement.

• Parallel PTAB IPR/PGR Proceedings:

  • While Sonos asserted multiple patents, and D&M Holdings was identified as a petitioner in a USPTO proceeding on March 7, 2017, available information does not specify if this IPR or any other instituted IPR/PGR proceeding by D&M Holdings directly challenged U.S. Patent No. 7,571,014 and significantly impacted the district court litigation prior to its settlement.
  • More recent PTAB filings (e.g., IPR2026-00021 filed by Google LLC against U.S. Patent No. 7,571,014) are not relevant to the D&M Holdings litigation, as they occurred after its termination. However, subsequent PTAB proceedings for other Sonos patents have referenced the claim constructions established in the Sonos v. D&M Holdings litigation, indicating its precedential value for certain claim terms.

Sonos, Inc. was represented by counsel from two primary law firms: Potter Anderson & Corroon LLP and Lee Sullivan Shea & Smith, LLP. Several attorneys from these firms were actively involved in the patent infringement case against D&M Holdings Inc..

Here is a breakdown of the identified counsel:

Potter Anderson & Corroon LLP (Wilmington, Delaware)

• Phillip A. Rovner
  • Role: Attorney for Plaintiff.
  • Firm: Potter Anderson & Corroon LLP, Wilmington, DE.
  • Experience Note: Phillip Rovner is a partner at Potter Anderson & Corroon and is noted for his work in intellectual property litigation, particularly in the District of Delaware. His practice includes a focus on patent and other complex commercial litigation.
• Jonathan A. Choa
  • Role: Attorney for Plaintiff.
  • Firm: Potter Anderson & Corroon LLP, Wilmington, DE.
  • Experience Note: Jonathan Choa is a partner at Potter Anderson & Corroon, with experience in intellectual property and complex commercial litigation in Delaware's federal and state courts.
• Richard L. Horwitz
  • Role: Of Counsel. (While a "retired partner" as of some recent mentions, he was active during the timeframe of this case).
  • Firm: Potter Anderson & Corroon LLP, Wilmington, DE.
  • Experience Note: Richard Horwitz, as a former partner and now Of Counsel at Potter Anderson, focused his practice on commercial litigation, including intellectual property, contract, and business tort matters.

Lee Sullivan Shea & Smith, LLP (Chicago, Illinois)

• George I. Lee
  • Role: Attorney for Plaintiff.
  • Firm: Lee Sullivan Shea & Smith, LLP, Chicago, IL.
  • Experience Note: George I. Lee is a founding partner of Lee Sullivan Shea & Smith, a firm specializing in intellectual property litigation. The firm represented Sonos in this case, and the principals had previous interactions with D&M, which was a point of contention regarding a disqualification motion that was denied.
• Sean M. Sullivan
  • Role: Attorney for Plaintiff.
  • Firm: Lee Sullivan Shea & Smith, LLP, Chicago, IL.
  • Experience Note: Sean M. Sullivan is a founding partner of Lee Sullivan Shea & Smith, with a focus on patent litigation.
• Rory P. Shea
  • Role: Attorney for Plaintiff (argued).
  • Firm: Lee Sullivan Shea & Smith, LLP, Chicago, IL.
  • Experience Note: Rory P. Shea is a founding partner of Lee Sullivan Shea & Smith and was noted for arguing on behalf of Sonos in this case. His firm specializes in intellectual property litigation.
• J. Dan Smith
  • Role: Attorney for Plaintiff.
  • Firm: Lee Sullivan Shea & Smith, LLP, Chicago, IL.
  • Experience Note: J. Dan Smith is a founding partner of Lee Sullivan Shea & Smith, involved in patent infringement matters.
• Michael P. Boyea
  • Role: Attorney for Plaintiff.
  • Firm: Lee Sullivan Shea & Smith, LLP, Chicago, IL.
  • Experience Note: Michael P. Boyea is an attorney with Lee Sullivan Shea & Smith, practicing in intellectual property litigation.

Local Counsel (Highly Probable, but not explicitly listed in the provided snippets for this specific case context)

• Kelly E. Farnan
  • Role: Likely local counsel.
  • Firm: Richards, Layton & Finger, P.A., Wilmington, DE.
  • Experience Note: Kelly Farnan is a highly regarded IP litigation attorney in the District of Delaware, frequently serving as local counsel in complex patent disputes for national and international companies. She has been recognized in Chambers USA and IAM Patent 1000.
• Stamatios Stamoulis
  • Role: Likely local counsel.
  • Firm: Stamoulis & Weinblatt LLC, Wilmington, DE.
  • Experience Note: Stamatios Stamoulis has over 20 years of experience in intellectual property and complex commercial law matters, including patent infringement cases in the District of Delaware. He is a founding member of Stamoulis & Weinblatt LLC.

Here is the counsel of record representing the defendant(s) in Sonos, Inc. v. D&M Holdings Inc. d/b/a THE D+M GROUP et al., Case No. 1:14-cv-01330:

For Defendants D&M Holdings Inc. d/b/a THE D+M GROUP, D&M Holdings U.S. Inc., and Denon Electronics (USA), LLC:

• Neal C. Belgam

  • Role: Local Counsel
  • Firm: Smith, Katzenstein & Jenkins LLP, Wilmington, DE
  • Experience Note: Highly experienced in acting as local Delaware counsel for both plaintiffs and defendants in intellectual property matters, including patent, trademark, and trade secret cases, with significant experience in the pharmaceutical, telecommunications, and technology sectors.

• Michael J. Kahn

  • Role: Lead Counsel (inferred from experience and firm role)
  • Firm: Akin Gump Strauss Hauer & Feld LLP, New York, NY (as of September 2015). (Note: Some later search results show him at Gibson Dunn in San Francisco, CA as of 2026, but his involvement in this case would have been with Akin Gump or a prior firm).
  • Experience Note: An experienced trial lawyer focusing on patent infringement disputes and related claims, with a global practice advising prominent life sciences and high-tech companies.

• John D. Garretson

  • Role: Lead Counsel (inferred from experience and firm role)
  • Firm: Shook, Hardy & Bacon L.L.P. (firm website lists him as Partner, office location not explicitly stated in snippets but generally a national practice)
  • Experience Note: Has a national patent litigation and counseling practice focused on pharmaceuticals, biotech, medical devices, and information technology, with experience in over 20 trials and appeals to the Federal Circuit.

• Joseph M. Paunovich

  • Role: Lead Counsel (inferred from experience and firm role)
  • Firm: Quinn Emanuel Urquhart & Sullivan, LLP, Los Angeles, CA (as of 2026, though firm at time of case may have varied)
  • Experience Note: Practices in a wide variety of complex and high-stakes civil matters, including intellectual property litigation, and is a registered patent attorney with trial experience.

• John M. Jackson

  • Role: Lead Counsel (listed as "Attorneys for Defendant" and argued)
  • Firm: Jackson Walker LLP, Dallas, TX
  • Experience Note: Counsel for defendants in the case, involved in arguments before the court.

• Blake T. Dietrich

  • Role: Counsel
  • Firm: Jackson Walker LLP, Dallas, TX
  • Experience Note: Listed as counsel for defendants in patent litigation.

• Michael J. Flynn

  • Role: Counsel (local counsel inferred from firm)
  • Firm: Morris Nichols Arsht & Tunnell LLP, Wilmington, DE
  • Experience Note: Part of the team representing defendants in the District of Delaware.

• Jack B. Blumenfeld

  • Role: Counsel (local counsel inferred from firm)
  • Firm: Morris Nichols Arsht & Tunnell LLP, Wilmington, DE
  • Experience Note: Part of the team representing defendants in the District of Delaware.

• Nathaniel (Nate) S. Pair II

  • Role: Counsel
  • Firm: Jackson Walker LLP, Dallas, TX
  • Experience Note: Listed as counsel for defendants.

• Matthew C. Acosta

  • Role: Counsel
  • Firm: Jackson Walker LLP, Dallas, TX
  • Experience Note: Listed as counsel for defendants.

• David Folsom

  • Role: Counsel
  • Firm: Jackson Walker LLP, Texarkana, TX
  • Experience Note: Listed as counsel for defendants.