Dbest Products Inc v. Zhejiang Xinmao Plastie Industry Co Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Dbest Products, Inc. (California)
  • Defendant: Zhejiang Xinmao Plastie Industry Co, Ltd. (China)
  • Plaintiff’s Counsel: Orbit IP, LLP
• Case Identification: 2:25-cv-04606, C.D. Cal., 05/21/2025
• Venue Allegations: Plaintiff asserts that venue is proper because Defendant is subject to personal jurisdiction in the district, noting that Defendant has done substantial business in the district and previously sued Plaintiff in the same court.
• Core Dispute: Plaintiff alleges that Defendant’s collapsible cart products infringe two U.S. patents related to structural mechanisms for enhancing the load capacity and stability of such carts.
• Technical Context: The technology concerns the field of portable, collapsible utility carts, a mature consumer product category where innovations often focus on improving durability and convenience.
• Key Procedural History: The complaint notes that Defendant previously sued Plaintiff in the Central District of California, a fact Plaintiff may use to establish personal jurisdiction.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 12,275,446 - High Load Capacity Collapsible Carts, issued April 15, 2025

The Invention Explained

• Problem Addressed: The patent identifies a weakness in prior art collapsible carts, noting that their collapsible design often results in sidewalls that are not "sufficiently sturdy to allow for transporting heavy objects" (’446 Patent, col. 1:13-16).
• The Patented Solution: To solve this, the invention discloses a locking mechanism to reinforce the hinged sidewalls when the cart is in its open, expanded state. The solution involves a "track" that spans across the two hinged panels of a sidewall and a "slideable member" that moves along this track. When moved into a closed position, this member locks the two panels together, preventing the sidewall from unintentionally folding inward under load (’446 Patent, col. 5:8-39; Abstract).
• Technical Importance: This design aims to provide the structural integrity of a rigid cart while retaining the storage convenience of a collapsible one, thereby increasing the cart's practical load capacity and stability (’446 Patent, col. 1:19-23).

Key Claims at a Glance

• The complaint asserts infringement of at least one unspecified claim of the '446 Patent (Compl. ¶15). Independent Claim 1 is representative and includes the following essential elements:
  • A collapsible cart configured to transition between a closed and an open condition.
  • A rigid frame with a front wall, rear wall, right sidewall, left sidewall, and bottom wall.
  • The right sidewall comprises a first right panel rotatably coupled to a second right panel.
  • A first track formed along the first and second right panels.
  • A first slideable member engaged with the track, movable between an open position and a closed position to selectively lock the first right panel to the second right panel.
• The complaint reserves the right to assert other claims, including dependent claims.

U.S. Patent No. 12,304,546 - Collapsible Carts, issued May 20, 2025

The Invention Explained

• Problem Addressed: Like the '446 Patent, this patent addresses the problem that prior art collapsible cart sidewalls "may not be sufficiently sturdy to allow for transporting heavy objects" due to their collapsible nature (’546 Patent, col. 2:25-27).
• The Patented Solution: The invention claims a collapsible cart with at least five walls, where opposing walls are comprised of two rotatably coupled panels. The key feature is a pair of "latch parts," one on the edge of each panel, which are configured to "mate with one another" to hold the panels in a common plane, thereby reinforcing the wall (’546 Patent, col. 13:34-44). The patent's detailed description clarifies that this mechanism is the same slideable lock shown in the figures common to both the '446 and '546 patents (’546 Patent, col. 6:45-7:22).
• Technical Importance: This solution provides a means to secure the cart's structure in an open configuration, enhancing its utility for carrying heavier loads than would otherwise be possible (’546 Patent, col. 2:25-29).

Key Claims at a Glance

• The complaint asserts infringement of at least one unspecified claim of the '546 Patent (Compl. ¶20). Independent Claim 1 is representative and includes the following essential elements:
  • A collapsible cart with a frame of at least five walls, where at least three walls can fold inwardly.
  • One of the opposing walls consists of a first panel and a second panel, rotatably coupled.
  • A first latch part on an edge of the first panel and a second latch part on an edge of the second panel.
  • The first and second latch parts are configured to mate to hold the panels in a common plane.
• The complaint reserves the right to assert other claims, including dependent claims.

III. The Accused Instrumentality

Product Identification

The complaint identifies the accused instrumentalities as "numerous products" sold by Defendant on Amazon.com, referred to generally as the "Accused Products" (Compl. ¶13). It states that a schedule of specific Amazon Standard Identification Numbers (ASINs) is attached as Exhibit C, but this exhibit was not provided with the complaint (Compl. ¶13).

Functionality and Market Context

The complaint does not provide any specific description of the Accused Products' features, functionality, or market position. It alleges in a conclusory manner that the products infringe the patents-in-suit (Compl. ¶¶15, 20).

IV. Analysis of Infringement Allegations

The complaint alleges that the Accused Products directly infringe the '446 and '546 patents (Compl. ¶¶15, 20). It states that representative claim charts demonstrating how the Accused Products satisfy each limitation of at least one claim of each patent are attached as Exhibits D and E, respectively (Compl. ¶¶15, 20). However, these exhibits are not provided with the filed complaint. The complaint itself offers no specific factual allegations detailing which features of the Accused Products correspond to the claim elements of the asserted patents. Therefore, an element-by-element analysis of the infringement theory is not possible from the face of the complaint.

No probative visual evidence provided in complaint.

Identified Points of Contention

• Pleading Sufficiency: A threshold issue is whether the complaint's conclusory allegations of infringement, which rely entirely on unattached exhibits, satisfy the plausibility standard required by Federal Rule of Civil Procedure 8, as interpreted by Twombly and Iqbal.
• Technical Correspondence: Assuming the case proceeds, the central technical dispute will concern whether the mechanism used in the Accused Products to stabilize their sidewalls, if any, functions in the same way as the claimed inventions. The analysis will question if the accused mechanism constitutes a "slideable member" on a "track" ('446 Patent) or mating "latch parts" ('546 Patent).

V. Key Claim Terms for Construction

Term 1: "slideable member cooperatively engaged to the first track" ('446 Patent, Claim 1)

• Context and Importance: This phrase captures the core of the asserted invention in the '446 Patent. The construction of "slideable member," "track," and "cooperatively engaged" will define the structural scope of the claim and will be central to determining infringement.
• Intrinsic Evidence for a Broader Interpretation: The claims use general terms without specifying a particular shape, size, or material for the member or track, which may support a construction covering a range of guided locking mechanisms (’446 Patent, col. 7:14-38).
• Intrinsic Evidence for a Narrower Interpretation: The specification consistently depicts a specific embodiment where the "slideable member" is a C-shaped clip (58) that slides along a raised rail forming the "track" (46) (’446 Patent, Figs. 2, 8; col. 5:16-24). A party may argue that the claim terms should be limited to this disclosed structure or its structural equivalents.

Term 2: "latch part" ('546 Patent, Claim 1)

• Context and Importance: This term appears in the '546 Patent in place of the "slideable member" and "track" language from the earlier-issued '446 Patent. Practitioners may focus on this term because the use of different terminology in a related patent for what appears to be an identical structure raises questions of prosecution history estoppel or whether a different scope was intended.
• Intrinsic Evidence for a Broader Interpretation: The term "latch part" is not explicitly defined and, in its ordinary sense, could encompass a wide variety of fasteners beyond the specific sliding mechanism shown. The claim only requires that the two "latch parts" are "configured to mate" (’546 Patent, col. 13:40-41).
• Intrinsic Evidence for a Narrower Interpretation: The '546 Patent shares a specification and drawings with the '446 Patent. The detailed description in the '546 Patent explicitly references the figures showing the "slideable member" (58) and "track" (46) when describing the invention, suggesting that "latch part" is simply another name for the components of that specific mechanism (’546 Patent, col. 6:45-7:22). This link could be used to argue for a narrow construction consistent with the '446 Patent's embodiment.

VI. Other Allegations

The complaint exclusively alleges direct infringement under 35 U.S.C. § 271 (Compl. ¶1). It does not contain allegations to support claims for indirect infringement or willful infringement.

VII. Analyst’s Conclusion: Key Questions for the Case

1. A threshold procedural question will be one of pleading sufficiency: Does the complaint, which makes conclusory allegations of infringement and relies on exhibits that are not attached, provide sufficient factual matter to state a plausible claim for relief, or is it subject to dismissal under Rule 12(b)(6)?
2. The central substantive issue will be one of claim construction and scope: How will the court construe the distinct terms "slideable member... on a... track" ('446 Patent) and "latch part" ('546 Patent), given that they appear in related patents and seem to describe the same structure? The outcome will determine whether the patents have different infringement scopes.
3. A key evidentiary question will be one of structural and functional correspondence: Assuming the case moves forward, does the mechanism on Defendant's products, if any, for reinforcing the sidewalls operate in a manner that falls within the construed scope of the claims of either patent, or does it represent a distinct, non-infringing design?