Tang v. Yiwushi Yanzhou: Trailer Hitch Patent Dispute Dismissed With Prejudice
Aiming Tang filed suit in the Northern District of Illinois asserting US11446973B1 — an adjustable ball mount trailer hitch patent — against Chinese seller Yiwushi Yanzhou Riyongbaihuo Shanghang over Amazon ASIN B09N7SSWHY. The parties jointly dismissed the case with prejudice after 186 days, each bearing its own costs and fees.
Cross-border hitch patent dispute ends in mutual walk-away
On 26 June 2025, individual inventor Aiming Tang filed a patent infringement action in the U.S. District Court for the Northern District of Illinois (Case No. 1:25-cv-07165) against Yiwushi Yanzhou Riyongbaihuo Shanghang, a Chinese consumer-goods trader. Tang alleged infringement of US11446973B1, a patent covering an adjustable ball mount trailer hitch, arising from the defendant’s sale of the PSAUTO Trailer Hitch product listed on Amazon under ASIN B09N7SSWHY.
The case closed on 29 December 2025 when both parties filed a joint stipulation of dismissal with prejudice pursuant to Fed. R. Civ. P. 41(a)(1)(A)(ii). Dismissal with prejudice is a final adjudication on the merits, barring Tang from reasserting the same infringement claims against Yiwushi Yanzhou in any future proceeding. Each party was ordered to bear its own attorneys’ fees and costs, suggesting no prevailing-party fee award was sought or granted.
At 186 days, the resolution is notably swift for patent litigation in the Northern District of Illinois, where contested cases routinely extend beyond two years. The speed and mutual cost-bearing terms are consistent with a negotiated resolution — potentially a licence, a design-around agreement, or a commercial settlement — though the public record does not disclose any financial or licensing terms. The with-prejudice designation permanently extinguishes these particular claims, providing Yiwushi Yanzhou with clean finality on this patent.
Filing to Dismissed with Prejudice in 186 days
186 days — resolved well within the typical 2–3 year N.D. Ill. patent trial timeline
Dismissed with prejudice: what the joint stipulation means for both parties
Rule 41(a)(1)(A)(ii) joint dismissal — with prejudice
A stipulated dismissal under Fed. R. Civ. P. 41(a)(1)(A)(ii) requires both parties’ signatures, making it a voluntary, consensual exit. The ‘with prejudice’ designation transforms what would otherwise be a procedural step into a final judgment on the merits. Tang cannot refile the same patent claims against this defendant in any U.S. court — the dismissal functions as a permanent bar to re-litigation of these specific claims.
Final — no refiling permittedTang permanently relinquishes these claims against Yiwushi Yanzhou
By agreeing to dismissal with prejudice, Tang forfeits the right to pursue infringement claims against this particular defendant based on the same acts. However, US11446973B1 itself remains in force and can still be asserted against other alleged infringers. The with-prejudice bar is defendant-specific, not patent-wide. If a private settlement accompanied this dismissal, its terms remain undisclosed in the public record.
Patent survives; claim extinguishedYiwushi Yanzhou secures permanent finality on these patent claims
The with-prejudice dismissal gives the defendant durable protection: Tang cannot re-open or refile these specific claims. The each-party-bears-own-costs structure means no fee exposure remained after resolution. The swift 186-day closure — before any substantive motion practice or claim construction — suggests the defendant either resolved the dispute commercially or reached agreement without admitting liability. No public finding of infringement or validity was made.
Permanent bar — no liability findingAmazon marketplace sellers face ongoing trailer hitch patent exposure
This case is consistent with a broader pattern of individual inventors and small IP holders targeting Chinese sellers operating on Amazon over mechanical accessory patents. The PSAUTO ASIN-specific allegation signals that product listings themselves can anchor infringement claims. Competing sellers of adjustable ball mount trailer hitches should note that US11446973B1 remains active and enforceable — Tang retains full standing to bring equivalent claims against other market participants.
Patent remains enforceableFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Aiming Tang | Individual | Individual inventor and patent holder — asserting US11446973B1 for adjustable ball mount trailer hitchSearch in Eureka ↗ |
| Defendant | Yiwushi Yanzhou Riyongbaihuo Shanghang | Individual | Chinese consumer-goods seller of trailer hitch products via Amazon marketplaceSearch in Eureka ↗ |
| Plaintiff counsel | Tao Liu | Attorney | Counsel for Aiming TangSearch in Eureka ↗ |
| Plaintiff counsel | Wei Wang | Attorney | Counsel for Aiming TangSearch in Eureka ↗ |
| Plaintiff law firm | Glacier Law LLP | Law Firm | Representing Aiming TangSearch in Eureka ↗ |
| Defendant counsel | Weilian Song | Attorney | Counsel for Yiwushi Yanzhou Riyongbaihuo ShanghangSearch in Eureka ↗ |
| Defendant counsel | Yi Yi | Attorney | Counsel for Yiwushi Yanzhou Riyongbaihuo ShanghangSearch in Eureka ↗ |
| Defendant law firm | LawMay P.C. | Law Firm | Representing Yiwushi Yanzhou Riyongbaihuo ShanghangSearch in Eureka ↗ |
| Defendant law firm | XYZ Law Firm, LLP | Law Firm | Representing Yiwushi Yanzhou Riyongbaihuo ShanghangSearch in Eureka ↗ |
| Presiding judge | Judge Lindsay C. Jenkins | Judge | Illinois Northern District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulated verdict text invokes Fed. R. Civ. P. 41(a)(1)(A)(ii) by name, confirming this was a bilateral, consent-based exit rather than a unilateral withdrawal. The explicit ‘with prejudice’ designation and symmetrical cost allocation — each party bears its own fees — are the operative terms. No damages, no injunction, no finding of infringement or invalidity appears on the record. The with-prejudice language is the commercially significant element: it is final and preclusive as to these claims between these parties.
US11446973B1 — Adjustable Ball Mount Trailer Hitch
US11446973B1 is a U.S. utility patent covering an adjustable ball mount trailer hitch — a mechanical device used to connect trailers to towing vehicles with variable height or angle adjustment. Filed under application number US17/751683, the patent issued to inventor Aiming Tang. Trailer hitch technology sits within the broader mechanical automotive accessories sector, where adjustability, load rating, and coupling interface geometry are typical points of differentiation and patentability.
From a competitive standpoint, a granted patent on an adjustable ball mount hitch design gives the holder standing to challenge structurally similar products across any sales channel, including e-commerce platforms. The Amazon marketplace context here is commercially significant: Chinese OEM sellers frequently manufacture near-identical mechanical accessories, and a single ASIN can represent substantial unit volume. Companies designing, importing, or distributing adjustable trailer hitch products should treat this patent as an active enforcement asset until its expiry.
Should you run an FTO analysis against US11446973B1?
Any company — or individual seller — importing, manufacturing, or listing adjustable ball mount trailer hitch products in the U.S. market should assess exposure against US11446973B1. The patent holder has demonstrated willingness to litigate in federal court. Given the ASIN-specific enforcement approach used here, even a single Amazon product listing can trigger infringement allegations. This is particularly relevant for automotive accessory importers, e-commerce sellers, and OEM suppliers sourcing from China.
PatSnap Eureka’s FTO Search Agent allows product teams to map their trailer hitch designs against the independent claims of US11446973B1, identify prior art that might support invalidity arguments, and surface related patent families that could expand or limit the risk perimeter. Running a structured FTO before launch or import — rather than after a cease-and-desist — dramatically reduces legal exposure and informs design-around decisions.
Run a freedom-to-operate analysis on US11446973B1 to assess your product’s exposure
Run FTO in Eureka →Similar trailer hitch and automotive accessory patent cases in N.D. Illinois
Cases involving mechanical automotive accessory patents — particularly trailer hitch and towing component claims — litigated in the Northern District of Illinois follow recognisable patterns.
What this case signals for the trailer hitch and automotive accessories IP landscape
A swift with-prejudice exit in a cross-border Amazon hitch dispute carries lessons for sellers, importers, and IP holders across the mechanical accessories sector.
Amazon ASIN-level patent targeting is an established enforcement tactic
The complaint tied infringement directly to Amazon ASIN B09N7SSWHY, a precise enforcement approach that allows patent holders to tie claims to specific product listings and sales records. Sellers of adjustable trailer hitch products on Amazon marketplaces should treat active mechanical patents as live risk factors and conduct FTO analysis before launching or importing competing SKUs.
With-prejudice dismissal protects the defendant — but only for this patent and this suit
Yiwushi Yanzhou is permanently protected against Tang’s claims under US11446973B1. However, the patent remains valid and in force. Other sellers of functionally similar products receive no protection from this dismissal. A competitor cannot rely on this case’s outcome as a shield — each potential infringer must assess their own exposure independently.
Tang v Yiwushi — key questions answered
The case was jointly dismissed with prejudice on 29 December 2025, 186 days after filing. Plaintiff Aiming Tang and defendant Yiwushi Yanzhou filed a stipulated dismissal under Fed. R. Civ. P. 41(a)(1)(A)(ii). Each party bears its own costs and fees. No liability finding or damages award was entered on the public record.
US11446973B1, filed under application US17/751683, covers an adjustable ball mount trailer hitch — a mechanical towing accessory that allows height or angle adjustment of the ball mount coupling. The patent was asserted against the defendant’s PSAUTO Trailer Hitch product listed on Amazon under ASIN B09N7SSWHY.
Dismissal with prejudice permanently bars Aiming Tang from refiling the same infringement claims against Yiwushi Yanzhou. However, US11446973B1 itself remains valid and enforceable. Tang retains full rights to assert the patent against any other alleged infringer. The preclusive effect is defendant-specific, not a general disclaimer of patent rights.
No. The with-prejudice dismissal binds only the parties to this action. Other sellers of adjustable ball mount trailer hitches on Amazon or elsewhere receive no protection from this case’s outcome. US11446973B1 remains active and can be enforced against any party whose product falls within the patent’s claim scope.
At 186 days, the case closed well before any typical patent litigation milestones such as claim construction or expert discovery. This pace is consistent with a negotiated commercial resolution — potentially a licence, royalty payment, or product modification agreement — though the public record discloses no settlement terms. The symmetrical cost allocation, with each party bearing its own fees, is also typical of mutually agreed exits rather than contested litigation outcomes.
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