IP Law Daily, PATENT—E.D. Ky.: Equine collar patent infringement claims upheld on summary judgment, (Jan 29, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

Defendant’s reverse doctrine of equivalents and employer-rights defenses failed; design and utility patents held literally infringed.

The federal district court in Lexington, Kentucky, granted summary judgment in favor of Linda’s Leather, LLC in its patent infringement lawsuit involving two equine anti-cribbing collar patents. The court ruled that the accused collar, manufactured and sold by horse trainer Victor Zambrano, infringed both the plaintiff’s U.S. Design Patent No. D869,783 (the ’783 patent) and U.S. Patent No. 10,398,129 (the ’129 patent). The court found literal infringement of both patents and rejected Zambrano’s arguments based on the reverse doctrine of equivalents, shop rights, and employer ownership theories and held that none of these defenses raised a genuine dispute of material fact (Linda's Leather, LLC v. Zambrano, No. 5:21-cv-00046-CHB-MAS (E.D. Ky. Jan. 27, 2026)).

Background. Linda’s Leather, LLC is a Kentucky-based company owned by leatherworker Linda Scott. It sells handcrafted leather goods, including specialty products for the equine industry. Victor Zambrano, a horse trainer and reseller of horse-related accessories, had a long-standing commercial relationship with Scott. In January 2015, Zambrano approached Scott to develop an anti-cribbing collar based on a sample made by his uncle. Scott improved the design through field trials and customer feedback and began selling the collars commercially in 2016.

Scott obtained both utility and design patents for her final collar design. She filed the provisional application in April 2016, a utility application in March 2017, and a design application in January 2017. The utility patent (the ’129 patent) issued in September 2019, and the design patent (the D’783 patent) issued in December 2019. All rights were assigned to Linda’s Leather in January 2020. Zambrano subsequently developed and marketed his own collar, which he patented in December 2021. Linda’s Leather sued Zambrano in February 2021 for infringement. Zambrano’s accused product, the “Zambrano Collar,” was similar in appearance and function and marketed for the same purpose: preventing cribbing in horses.

Literal infringement. The court found that Zambrano’s collar literally infringed both the D’783 design and the ’129 utility patents held by Linda’s Leather. For the design patent, it applied the “ordinary observer” test first articulated in Gorham Mfg. Co. v. White, 81 U.S. 511 (1871), and reaffirmed in Egyptian Goddess, Inc. v. Swisa, Inc., 543 F.3d 665 (Fed. Cir. 2008). The court concluded that the Zambrano collar was “virtually indistinguishable” from the patented design and noted that several customers had mistaken Zambrano’s collars for the plaintiffs. Zambrano did not contest the visual similarity in his response.

As to the ’129 utility patent, the court determined that the accused product satisfied every limitation of the asserted independent claims. The collar included a main collar strip, an alligator flap with a hook-and-loop fastener material, and a secondary securement strap—all structural elements required by the patent. Relying on Maxwell v. J. Baker, Inc., 86 F.3d 1098 (Fed. Cir. 1996), the court held that Linda’s Leather had established literal infringement as a matter of law. Zambrano failed to raise any genuine factual dispute as to the presence of any claim element.

Patent grant not a shield. Zambrano argued that because the U.S. Patent and Trademark Office granted him his own patent, U.S. Patent No. 11,207,814, his product could not infringe. The court rejected this position. A patent grants a right to exclude others, not a right to practice the claimed invention. Citing Glaxo Wellcome, Inc. v. Andrx Pharms., Inc., 344 F.3d 1226 (Fed. Cir. 2003), and Atlas Powder Co. v. E.I. du Pont De Nemours & Co., 750 F.2d 1569 (Fed. Cir. 1984), the court emphasized that separate patentability does not negate infringement. A patented improvement can still infringe an earlier patent.

Reverse doctrine dismissed. Zambrano also asserted a defense under the reverse doctrine of equivalents, claiming that his collar was materially different due to enhanced rigidity. The court found the argument insufficient to raise a triable issue of fact. Citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605 (1950), and Roche Palo Alto LLC v. Apotex, Inc., 531 F.3d 1372 (Fed. Cir. 2008), the court explained that this equitable doctrine applies only where the accused device performs the same function in a substantially different way. Zambrano did not identify the “principle” of the patented invention or explain how his design deviated from it. Both collars prevented cribbing in the same manner, using a rigid strap, hook-and-loop closure, and a secondary anchoring strap. The court also cited Steuben Foods, Inc. v. Shibuya Hoppmann Corp., 127 F.4th 348 (Fed. Cir. 2025), noting that the Federal Circuit has never affirmed a noninfringement finding based on this rarely used doctrine.

No implied employment relationship. Zambrano further claimed that Scott developed the patented collar as his employee under an implied-in-fact contract. The court disagreed. Applying Banks v. Unisys Corp., 228 F.3d 1357 (Fed. Cir. 2000), the court found no evidence of mutual assent or control. Invoices between the parties reflected fixed prices for finished products, not payments for time or development services. Bank records showed that Scott purchased her own materials and equipment. The court concluded that no employment relationship existed and that there was no agreement to assign patent rights to Zambrano.

No shop rights. Finally, Zambrano argued that he held shop rights in the patented invention. The court rejected this theory as well. Shop rights arise when an invention is developed using the employer’s time, tools, or materials. Citing McElmurry v. Arkansas Power & Light Co., 995 F.2d 1576 (Fed. Cir. 1993), the court noted that Scott created the collar independently in her own workshop, using her own resources. As Zambrano contributed neither facilities nor funding, he was not entitled to a royalty-free license.

Conclusion. Thus, the court granted summary judgment for Linda’s Leather and denied all other motions, including motions in limine and to compel mediation, as moot. The court allowed the plaintiff to refile a separate motion on sanctions and directed the parties to submit a joint status report on the remaining issues, including damages and settlement, by February 9, 2026.

The Case is No. 5:21-cv-00046-CHB-MAS.

Judge: Boom, C.

Attorneys: Kevin Todd Duncan (Duncan Galloway Greenwald, PLLC) for Linda's Leather, LLC. Edward L. Yancy (Law Office of Edward L. Yancy) for Victor Zambrano.

Companies: Linda's Leather, LLC

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