The U.S. Open tennis championships are currently underway in New York, with the main draw starting on a Sunday for the first time. In the singles competition, top players like Emma Raducanu, Novak Djokovic, and Aryna Sabalenka are headlining the early rounds. Amidst the on-court action, intellectual property (IP) remains a key component of the tennis world, extending beyond player endorsements and brand protection to include patent litigation over technologies used in the game itself.
Indeed, tennis is not only played or decided on tennis courts. From racquet technologies to retractable roofs, IP disputes have shaped the sport's technology, marketing, and even its venues. We look at a few intriguing cases and storylines where decisions were not made by a chair umpire, a line umpire, or a referee, but by a judge in a courtroom or by parties to the dispute.
A. Patent and Technology Disputes
Group One Ltd. v. GTE GmbH[1]
Group One, a competitor, accused GTE GmbH and its founder, Ralf Weigel, of directly, contributorily, and willfully infringing Group One's patents related to let-detection technology. The core of the infringement claims involved GTE's "Trinity" system used at the 2019 and 2020 U.S. Opens. The "let-detection" systems are related to determining if a tennis ball has hit the top of the net during a serve.
A notable issue was the court's jurisdiction over the foreign defendants (GTE GmbH and Weigel, both in Germany). The court addressed whether service of process by email was sufficient under the Hague Convention, ultimately concluding that it was, as long as it comported with due process. This finding is particularly relevant for practitioners dealing with international litigation.
Another issue was Group One's attempt to hold a non-party, the United States Tennis Association (USTA), in contempt for using an allegedly infringing product. The court denied this motion, ruling that it lacked the authority to enjoin a non-party unless it was acting in concert with a party. The court also clarified that a non-party could not be enjoined for using a product not supplied by the defendants in the lawsuit.
The District Court issued a default judgment against GTE and Weigel for patent infringement, false advertising, and other claims. Group One was awarded lost profits for the 2019 and 2020 U.S. Opens, but not for other tournaments. On appeal[2], the Federal Circuit affirmed the District Court's decisions on damages and contempt. However, the Federal Circuit reversed the District Court's failure to award post-judgment interest and sent the case back to determine the amount.
Prince v. Wilson (and Frolow)
These cases[3], which reached the Federal Circuit, involved patent disputes that grew out of a licensing agreement between the two sporting goods giants. The core issue was whether certain Wilson tennis rackets infringed claims in patents owned by Jack Frolow, to which Wilson had a license Prince, a competitor, was also involved as a licensee.
The most significant legal takeaway from the appellate court's decision[4] was its analysis of "marking estoppel." Frolow argued that because Wilson had marked some of its racquets with the patent number, it should be "estopped" from later claiming those same racquets did not infringe the claims in that patent.
The Federal Circuit rejected the doctrine of marking estoppel, stating it was not a recognized legal principle. However, the Court did find that the act of marking a product with a patent number serves as circumstantial evidence, an "extrajudicial admission", that the product falls within the patent's scope. The Federal Circuit reversed the District Court's summary judgment, ruling that the evidence of Wilson's marking was sufficient to create a genuine issue of material fact for a jury to decide. In essence, while marking does not automatically create liability, it can be powerful evidence of infringement.
Retractable roofs and trade secrets at Arthur Ashe Stadium
The engineering firm Uni-Systems LLC, a developer of retractable roof technology, filed a lawsuit[5] in 2017 against several contractors and suppliers behind the U.S. Open's Arthur Ashe Stadium roof project. The suit, filed in the U.S. District Court for the Eastern District of New York, alleged both patent infringement and trade-secret misappropriation.
The trade secret dispute centered on an earlier collaboration between Uni-Systems and one of the defendants, Hunt Construction Group, Inc., for a retractable roof project at the University of Phoenix Stadium (now State Farm Stadium) in Arizona. Uni-Systems alleged that Hunt, in collaboration with the engineering firm Hardesty & Hanover, used a maintenance contract on the Arizona project as a way to steal Uni-Systems' proprietary technology and trade secrets, including operational software and detailed design specifications.
The lawsuit also accused the defendants of infringing two of Uni-Systems' patents related to retractable roof design: U.S. Patent No. 6,789,360[6] ("Retractable Roof System for Stadium") and U.S. Patent No. 7,594,360[7] ("Lateral Release Mechanism for Movable Roof Panels"). Uni-Systems claimed that the roofs at both Arthur Ashe Stadium and the new Louis Armstrong Stadium infringed the claims of these patents.
The case involved numerous defendants, including the USTA, Skanska USA (as a successor to Hunt Construction), and other engineering and construction firms. While the specific terms of a final resolution are not public, court filings and legal news reports indicate the case was ultimately settled. Venue construction disputes highlight how stadium infrastructure is laden with IP risk.
B. Trademarks, False Advertising, and Brand Control
Penn (Head) v. Dunlop
In a case of false advertising under the Lanham Act, Head USA Inc. and its subsidiary, Penn Racquet Sports Inc., sued rival Dunlop International Ltd. over its claim of selling the "#1 ball in America." The lawsuit was filed in federal court in Connecticut[8]. Penn accused Dunlop of misleading the public by advertising its tennis balls with the slogan "The World's No. 1 Ball" and a related claim of having a 70% global market share. Penn argued that Dunlop's claims were factually false and that Penn, in fact, held the largest market share in the United States, making Dunlop's "No. 1" claim misleading to American consumers.
The case is an example of a Section 43(a) Lanham Act claim. This federal law governs false advertising and unfair competition. For a claim to succeed, the plaintiff must typically show that the defendant made a false statement of fact in advertising that is material and likely to deceive a substantial portion of the target audience, causing injury to the plaintiff. The burden of proof would have fallen on Dunlop to substantiate its "#1" claim, likely through reliable market data or surveys.
While the specific terms of the resolution are not publicly available, such high-profile false advertising cases are often resolved through confidential settlements.
Babolat false-advertising class action
This lawsuit[9] alleged that Babolat misled consumers into believing that the tennis rackets sold at retail were identical to those used by professional players, such as Rafael Nadal. This practice, known as "misleading endorsements" or "product parity claims," formed the basis of the legal action. The consumers argued that they were induced to purchase the commercial racquets under the false premise that they were getting the same high-performance product used by elite athletes, when in fact, the pro-player frames were often custom-made with different materials, specifications, and weight balances.
Federal Trade Commission (FTC) guidelines[10] for endorsements require that endorsements reflect the honest opinions, findings, or experiences of the endorser. When a product is not truly the same, a company risks violating these rules and triggering liability.
The case sheds light on the frequent practice in professional sports of using "pro stock" or custom equipment that is not available at retail. This creates a legal gray area where the line between aspirational advertising and deceptive marketing can become blurred. Companies must be careful to avoid implying a direct link between the pro gear and the retail product if they are not, in fact, identical.
The case resulted in a class action settlement for $4.5M, underscoring how endorsements and product parity claims can trigger liability. The significant settlement amount serves as a warning to brands that the financial and reputational costs of misleading advertising can be substantial, especially when consumer trust is a key part of the brand's value proposition.
Roger Federer's 'RF' logo
This dispute centered on the ownership of the "RF" logo, a stylized monogram of Roger Federer's initials that became synonymous with his brand. When Roger Federer was in a long-term sponsorship deal with Nike, the company created the "RF" logo for him. As part of their contract, Nike registered the "RF" trademark in various classes covering clothing and footwear, making it the legal owner of the intellectual property. When Federer left Nike for Uniqlo, Nike still owned the 'RF' trademarks.
This meant that even though they were Federer's initials, he could not use the mark with his new sponsor without a license from Nike. Federer said[11] his hope that Nike would be "nice and helpful in the process" of returning the logo, emphasizing that they were his initials and "not theirs forever."
The dispute was not a formal lawsuit in court but a negotiation that took place behind the scenes. Nike stopped selling "RF"-branded merchandise, and after a period of approximately two years, they assigned the trademark rights to Tenro AG, a company owned by Federer that manages his intellectual property[12]. The details of the agreement were not made public, but it is widely believed that Federer paid a considerable sum to regain control of his brand. Tenro owns[13] other trademarks associated with Federer.
The dispute serves as a cautionary tale, illustrating that even an individual's own initials can become the property of a corporation if the company is responsible for creating and registering the trademark. The outcome shows the immense leverage a top-tier athlete holds.
This case highlights the crucial importance for athletes to address intellectual property ownership in their sponsorship contracts. A better-structured deal from the outset could have included a clause that automatically transferred trademark rights back to the athlete upon the termination of the agreement.
C. Copyrights
Artist v. USTA
In Noonan v. USTA[14], the dispute arose over a T-shirt sold by the USTA at the US Open that featured a design inspired by the New York City subway map. Mark Noonan, a freelance artist and designer, had created a distinctive, stylized version of the New York City subway map as part of his "NYC Subway Series" artwork. Noonan claimed that the USTA sold t-shirts at its gift shops during the 2011 U.S. Open that copied his unique "subway-style map" design, which featured tennis-related locations and was registered with the U.S. Copyright Office. He alleged that the USTA's shirt was a "blatant copy" of his work, infringing on his copyright.
While a factual map itself is not copyrightable, the artistic expression and selection of elements, colors, and design can be. Noonan's case rested on the argument that his specific stylized design was original enough to warrant copyright protection.
The case was also ultimately settled out of court. The specific terms of the settlement were not publicly disclosed. The case serves as a good example of the risks that large organizations face when using artistic designs for merchandise without properly licensing the work from its creator.
D. Key Takeaways
Game-day success relies just as much on foresight in IP strategy as it does on on-court performance of the players. Each case provides significant takeaways both for sports executives and legal practitioners:
Group One v. GTE GmbH: Courts can find that email is a valid method for international legal service, and a plaintiff cannot seek to hold a non-party in contempt for using an allegedly infringing product not supplied by the defendants.
Prince v. Wilson (and Frolow): While not legally binding, marking a product with a patent number can serve as powerful circumstantial evidence of infringement in court.
Uni-Systems v. US Open Contractors: A company's trade secrets can be protected even during a collaborative project, and IP risks extend to complex infrastructure like retractable stadium roofs.
Penn (Head) v. Dunlop: Superlative advertising claims like "#1" must be factually substantiated with data to avoid liability under false advertising laws.
Babolat Class Action: Brands face significant liability for misleading consumers with product parity claims, especially when pro-stock equipment is different from what is sold at retail.
Roger Federer's 'RF' Logo Saga: Athletes should secure ownership of their IP in endorsement contracts, as a corporation that creates a logo can legally own it, even if it is based on an athlete's name.
Artist v. USTA: Large organizations must properly license creative designs for merchandise, as even stylized artistic interpretations of public domain items, like maps, are protected by copyright.
[1] Group One Ltd. v. GTE GmbH, 523 F. Supp. 3d 323 (E.D.N.Y. 2021)
[2] Group One Ltd. v. GTE GmbH, No. 24-1273 (Fed. Cir. Aug. 21, 2025)
[3] Prince Sports Group, Inc. v. Wilson Sporting Goods Co., 42 F.3d 1408 (Fed. Cir. 1994) (addressing jurisdictional issues and the scope of appealability regarding a settlement and subsequent patent dispute), Prince Sports Group, Inc. v. Wilson Sporting Goods Co., 91 F.3d 167 (Fed. Cir. 1996) (addressing summary judgment on noninfringement and the district court's refusal to rule on patent invalidity), Frolow v. Wilson Sporting Goods Co., 710 F.3d 1303 (Fed. Cir. 2013) (addressed breach of a license agreement and whether certain tennis racket models qualified as "Licensed Articles" under a patent license.)
[4] Frolow v. Wilson Sporting Goods Co., 710 F.3d 1303 (Fed. Cir. 2013)
[5] Uni-Systems, LLC v. U.S. Tennis Ass'n, Inc., 350 F. Supp. 3d 143 (E.D.N.Y. 2018)
[6] https://patents.google.com/patent/US6789360B2
[7] https://patents.google.com/patent/US7594360B2
[8] Head USA Inc. et al. v. Dunlop Sports Group Americas Inc. et al., Case No. 3:12-cv-00624-AWT (D. Conn. filed Apr. 30, 2012)
[9] Ahdoot et al. v. Babolat VS North America Inc. et al., Case No. 2:13-cv-02823 (C.D. Cal. filed Apr. 17, 2013)
[10] Section 5 of the FTC Act (15 U.S.C. § 45)
[11] https://www.tennisworldusa.org/tennis/news/Roger_Federer/85009/roger-federer-recovers-rf-logo-from-nike/ (last accessed August 22, 2025)
[12] https://www.sportspro.com/news/roger-federer-rf-logo-us-trademark-tenro-nike-uniqlo/#:~:text=Roger%20Federer%20has%20reclaimed%20his,and%20Trademark%20Office%20(USPTO). (last accessed August 22, 2025)
[13] https://www.trademarkia.com/owners/tenro-ag (last accessed Aug. 23, 2025)
[14] Noonan v. U.S. Tennis Ass'n, Case No. 1:11-cv-06103 (S.D.N.Y. filed Aug. 31, 2011)
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