Fei Deng v. MOZACI: Design Patent Dispute Ends in Voluntary Dismissal

Case Overview

The Parties

The Patent at Issue

This case involved a U.S. Design Patent covering the ornamental design of a square fidget pop keychain:

• • US D1032188S — The ornamental design of a square fidget pop keychain

The Accused Product

The accused product is a square fidget pop keychain — a consumer novelty item in the sensory toy and stress-relief accessories market. This product category surged in commercial popularity and has become a recurring subject of both design and utility patent disputes, particularly among e-commerce sellers operating on platforms such as Amazon and similar marketplaces.

Litigation Timeline & Procedural History

The complaint was filed on March 27, 2025, in the U.S. District Court for the Northern District of Illinois — a venue with an established docket for intellectual property matters and a judiciary experienced in patent disputes. Chief Judge Sunil R. Harjani presided over the matter.

The case closed on June 11, 2025, after Deng filed a notice of voluntary dismissal [Docket No. 36]. At just 76 days from filing to termination, the timeline reflects a pre-trial resolution — suggesting that substantive litigation milestones such as claim construction briefing, discovery disputes, or summary judgment motions either did not materialize or catalyzed an early settlement or strategic withdrawal.

The speed of resolution — well under three months — is notable even by the standards of design patent cases, which often resolve faster than utility patent disputes given their narrower claim scope and more streamlined infringement analysis.

The Verdict & Legal Analysis

Outcome

The case was dismissed with prejudice pursuant to Fed. R. Civ. P. 41(a)(1)(A)(ii), which governs voluntary dismissals filed with the opposing party’s written consent after the defendant has served an answer or motion for summary judgment. Dismissal with prejudice means Deng cannot re-file the same claims against MOZACI based on the same patent and accused product. Each party was ordered to bear its own attorneys’ fees and costs, and all pending motions, hearings, and deadlines were stricken by Chief Judge Harjani.

No damages were awarded. No injunction was issued.

Verdict Cause Analysis

The court record reflects that this matter was terminated through the parties’ mutual agreement — not as the result of a judicial ruling on patent validity, claim construction, or infringement. The specific terms that prompted Deng to file for voluntary dismissal with prejudice are not disclosed in the public docket entry. Possible explanations, based on common litigation dynamics in analogous cases, include:

• Confidential settlement: The parties may have reached a private agreement — potentially involving a licensing arrangement, design modification, or monetary consideration — with the voluntary dismissal serving as the mechanism of record.
• Strategic withdrawal: Plaintiff may have reassessed litigation economics, evidentiary challenges, or the strength of the infringement position following early-stage defense filings.
• Defendant’s responsive posture: The retention of YoungZeal LLP and the filing of a formal response (required for Rule 41(a)(1)(A)(ii) to apply) may have introduced invalidity arguments or design-around evidence that altered plaintiff’s calculus.

Note: The specific terms of any resolution were not publicly disclosed in the available case record.

Legal Significance

Because the dismissal was entered with prejudice, the case has no precedential value on the substantive questions of design patent infringement, the scope of USD1032188S’s claim coverage, or validity under 35 U.S.C. §§ 102 or 103. However, the procedural outcome carries practical significance:

• The “with prejudice” designation forecloses re-litigation of this specific dispute, providing MOZACI with finality and protection from re-assertion by Deng on the same patent-product combination.
• The mutual cost-bearing arrangement suggests a balanced negotiation — neither party extracted a fee-shifting outcome under 35 U.S.C. § 285, which requires a finding of an “exceptional case.”

Industry & Competitive Implications

The fidget and sensory toy market expanded rapidly during and after the COVID-19 pandemic, generating a proliferation of similar-looking consumer products across e-commerce platforms. This environment has produced a corresponding wave of design patent filings and enforcement actions by individual inventors and small IP holding entities targeting online sellers.

Fei Deng v. MOZACI fits a recognizable pattern: an individual design patent holder asserting rights against a single defendant in a consumer novelty category, with the case resolving before any substantive judicial ruling. This litigation model — sometimes characterized as “assertion-and-resolve” — reflects both the accessibility of design patent enforcement and the economic pressures that often drive early resolution.

For companies distributing consumer products through e-commerce channels, this case reinforces the importance of:

1. Conducting design patent clearance searches before product launch
2. Maintaining records of design provenance and prior art for rapid invalidity response
3. Engaging IP counsel capable of early-stage case assessment and negotiation

The broader takeaway for the novelty product sector is that design patent litigation in this space tends to resolve quickly, with outcomes driven more by negotiation dynamics than by judicial resolution on the merits.

FAQ

What patent was at issue in Fei Deng v. MOZACI?

The case involved U.S. Design Patent No. USD1032188S (Application No. US29/874526), covering the ornamental design of a square fidget pop keychain.

Why was the case dismissed with prejudice?

Plaintiff Fei Deng filed a notice of voluntary dismissal pursuant to Fed. R. Civ. P. 41(a)(1)(A)(ii). The specific reasons were not publicly disclosed, though such outcomes commonly reflect a private resolution or strategic reassessment.

What does this case mean for design patent enforcement in consumer products?

It reflects a broader pattern of rapid-resolution design patent enforcement in the consumer novelty space, underscoring the importance of early FTO analysis and prompt legal engagement for sellers in high-density design patent markets.