Antonelli, Harrington & Thompson

Antonelli, Harrington & Thompson LLP: Patent Litigation Summary

Date: 2026-05-01

Firm Overview:
Antonelli, Harrington & Thompson LLP is a patent litigation boutique based in Houston, Texas. The firm was founded by three partners—Matthew J. Antonelli, Zachariah S. Harrington, and Larry D. Thompson, Jr.—all of whom previously practiced at Weil, Gotshal & Manges. The firm presents itself as a lean, trial-focused team that rejects the traditional "pyramid structure" of large law firms, and one business directory lists the firm as having approximately 10 employees. While the firm is not ranked in major legal directories like the AmLaw 200 or Chambers and Partners, which typically survey larger firms, its partners are active and visible in patent litigation circles.

IP Litigation Specialty and Side Preference:
The firm focuses exclusively on patent litigation, with a clear preference for representing patent holders on the plaintiff's side. Its business model favors contingency-fee or fixed-fee arrangements, aligning its interests with patent-enforcement campaigns. The firm’s litigation activity is concentrated in popular patent venues like the U.S. District Court for the Eastern District of Texas. Public records show the firm representing non-practicing entities (NPEs) and patent assertion entities such as Modulus Systems LLC, American Patents LLC, and Fall Line Patents, LLC. The technologies at issue in these cases include wireless communications (Wi-Fi MIMO), signal processing, and computer-implemented systems for data management and mobile-app transactions.

Notable Cases and Outcomes:
The firm is currently representing Modulus Systems LLC in a patent infringement case filed in April 2026 in the Eastern District of Texas. In recent years, the firm has handled litigation campaigns for other patent-assertion clients. For instance, it represented Fall Line Patents in a series of lawsuits against national restaurant and retail chains, including Jersey Mike's and Chipotle, over a patent related to mobile application ordering systems; these cases ended in joint dismissals, suggesting confidential settlements. Similarly, the firm represented Freedom Patents, LLC in a 2024 case against Samsung asserting three Wi-Fi patents, which was dismissed just 70 days after being filed, also indicating a likely settlement. An article from 2019 noted the firm had filed 25 patent cases in 2018.

PTAB / IPR Practice and Key Partners:
Antonelli, Harrington & Thompson is also active before the Patent Trial and Appeal Board (PTAB), primarily in a defensive capacity for patent owners facing inter partes review (IPR) challenges. The firm has represented patent owner American Patents LLC in multiple IPRs filed by parties such as Juniper Networks and Hewlett Packard Enterprise, with court records showing these proceedings often terminate due to settlement. The firm also represented American Patents on appeal to the U.S. Court of Appeals for the Federal Circuit, which affirmed a PTAB decision invalidating a network patent. The firm’s key partners are its founders: Matthew J. Antonelli, Zachariah S. Harrington, and Larry D. Thompson, Jr. Mr. Harrington and Mr. Thompson are frequently listed on PTAB filings as counsel for the patent owner.