Dbest Products Inc v. Luoyang Muzhou Department Store Sales Co Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Dbest Products, Inc. (California)
  • Defendant: Luoyang Muzhou Department Store Sales Co., Ltd (China)
  • Plaintiff’s Counsel: Orbit IP, LLP
• Case Identification: 2:25-cv-04613, C.D. Cal., 05/21/2025
• Venue Allegations: Plaintiff alleges venue is proper in the Central District of California because Defendant is subject to personal jurisdiction in the district, based on conducting substantial business there, including the alleged acts of infringement.
• Core Dispute: Plaintiff alleges that Defendant’s collapsible cart products, sold online, infringe two patents related to structural and locking mechanisms for such carts.
• Technical Context: The case concerns the market for portable, collapsible utility carts, where design features that enhance durability and load capacity while maintaining collapsibility are a point of competition.
• Key Procedural History: The complaint alleges that Plaintiff marks its products with the relevant patent numbers, an action intended to provide constructive notice to the public and potential infringers.

Case Timeline

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

U.S. Patent No. 12,275,446 - High Load Capacity Collapsible Carts

The Invention Explained

• Problem Addressed: The patent identifies a problem in prior art collapsible carts where the collapsible nature of the sidewalls makes them insufficiently sturdy for transporting heavy objects (’446 Patent, col. 1:12-16).
• The Patented Solution: The invention addresses this by creating a more rigid sidewall. The sidewalls are constructed from two separate panels that are hinged together. A "slideable member" is mounted on a "track" that spans the joint between the two panels. When the cart is open, a user can slide this member across the joint into a locked position, securing the two panels into a single, more rigid plane (’446 Patent, Abstract; col. 5:15-30). This locking mechanism is illustrated in figures such as FIG. 2, which shows the slideable member (58) on its track (46).
• Technical Importance: This design purports to offer the convenience of a collapsible cart with the structural integrity of a more rigid container by actively locking the folding sidewalls into a fixed, load-bearing state.

Key Claims at a Glance

• The complaint asserts at least one claim of the patent (’446 Patent, Compl. ¶15). Independent Claim 1 is representative.
• Essential elements of Claim 1 include:
  • A collapsible cart configured to transition from a closed condition to an open condition.
  • A rigid frame forming a compartment with front, rear, right, left, and bottom walls.
  • The right sidewall comprising 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 does not specify if dependent claims are asserted but reserves the right to identify them later.

U.S. Patent No. 12,304,546 - Collapsible Carts

The Invention Explained

• Problem Addressed: Similar to the ’446 patent, this patent addresses the structural weakness of conventional collapsible cart sidewalls, which limits their ability to carry heavy loads (’546 Patent, col. 1:24-27).
• The Patented Solution: This invention discloses a cart with a frame of at least five walls, where opposing collapsible walls are made of a first and a second panel hinged together. To enhance rigidity, the edges of these panels include corresponding "latch parts." When the cart is unfolded, these latch parts are configured to "mate with one another," holding the two panels together in a common plane to form a sturdy, continuous wall (’546 Patent, Claim 1). The summary describes this as a "lock assembly" that can be integrated into the panels themselves to provide structural integrity (’546 Patent, col. 2:44-65).
• Technical Importance: This approach seeks to improve load capacity by using integrated latching features on the panel edges, providing a different mechanical solution to the same problem of sidewall instability.

Key Claims at a Glance

• The complaint asserts at least one claim of the patent (’546 Patent, Compl. ¶20). Independent Claim 1 is representative.
• Essential elements of Claim 1 include:
  • A collapsible cart with a frame of at least five walls, three of which are configured to fold inwardly.
  • One of the opposing walls consists of a first panel and a second panel rotatably coupled together.
  • A first latch part disposed on an edge of the first panel.
  • A second latch part disposed on an edge of the second panel.
  • The first and second latch parts are configured to mate with one another to hold the panels in a common plane.
• The complaint does not specify if dependent claims are asserted.

III. The Accused Instrumentality

Product Identification

The complaint identifies the "Accused Products" as "numerous products" sold by the Defendant on Amazon.com (Compl. ¶13). A specific list of products by Amazon Standard Identification Number (ASIN) is referenced as Exhibit C to the complaint, which was not publicly available for this analysis (Compl. ¶13, Ex. C).

Functionality and Market Context

The complaint alleges the Accused Products are collapsible carts offered for sale and sold to consumers in the United States, including within the judicial district (Compl. ¶11, ¶18). The complaint does not contain specific descriptions or technical details about the operation of the Accused Products beyond the conclusory allegation that they infringe the patents-in-suit (Compl. ¶13). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint references, but does not include, claim chart exhibits that purportedly detail the infringement of each patent (Compl. ¶15, Ex. D; ¶20, Ex. E). The infringement theory presented in the body of the complaint is therefore general.

For the ’446 Patent, the complaint alleges that Defendant directly infringes by selling Accused Products that satisfy each limitation of at least one claim (Compl. ¶15). This suggests the Accused Products are alleged to possess a collapsible frame with hinged, multi-panel sidewalls that are locked into a planar configuration by a sliding member that moves along a track spanning the panels.

For the ’546 Patent, the complaint makes a parallel allegation of direct infringement (Compl. ¶20). The narrative theory suggests the Accused Products are alleged to feature multi-panel sidewalls with integrated "latch parts" on their edges that mate together to secure the panels into a rigid, coplanar wall when the cart is in its open, expanded state.

• Identified Points of Contention:
  • Factual Question: A primary point of contention will be establishing the specific design and operation of the Accused Products. The central factual question is whether the accused carts actually incorporate the specific mechanical structures recited in the patent claims—namely, the "slideable member" on a "track" of the ’446 Patent or the mating "latch parts" of the ’546 Patent.
  • Scope Questions: The dispute may turn on the scope of the claims. For example, does the "track" claimed in the ’446 Patent require a specific channel-and-groove structure as depicted in the patent's figures, or can it read on any guide-like feature? Similarly, what degree of physical interaction is required for the "latch parts" of the ’546 Patent to "mate with one another"?

V. Key Claim Terms for Construction

’446 Patent

• The Term: "first slideable member cooperatively engaged to the first track" (from Claim 1).
• Context and Importance: This phrase defines the core locking mechanism of the invention. The infringement analysis will depend heavily on what constitutes a "cooperatively engaged" slideable member and "track." Practitioners may focus on this term because its construction will determine whether a variety of different locking mechanisms fall within the claim's scope.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language itself does not specify the precise geometry of the engagement, which could support a construction covering any mechanism where one part slides along another to perform the locking function.
  • Evidence for a Narrower Interpretation: The specification describes and illustrates a specific embodiment where the slideable member (58) moves along a defined track (46) to secure the panels (26, 28) (’446 Patent, col. 5:15-30; FIG. 2). A defendant may argue that the term should be limited to this disclosed structure or its equivalents.

’546 Patent

• The Term: "latch part... configured to mate with one another" (from Claim 1).
• Context and Importance: This phrase is central to the claimed invention in the ’546 Patent, defining how the separate panels of a sidewall are secured. The case may turn on the definition of "mate," as it dictates the type of connection required for infringement.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent does not provide a specific definition for "latch part" or "mate," nor does it appear to limit the terms to a single embodiment. Plaintiff may argue the terms should be given their plain and ordinary meaning, which could encompass a wide range of interlocking, fastening, or connecting features.
  • Evidence for a Narrower Interpretation: A defendant may argue that the term "mate" implies a specific geometric correspondence between the two latch parts (e.g., a male-female connection) and that a simpler abutment or friction-fit mechanism would not qualify. The absence of a detailed embodiment, however, may make this a more difficult argument to sustain.

VI. Other Allegations

• Willful Infringement: The complaint does not explicitly allege willful infringement. It does, however, request an award of attorneys' fees, a remedy available in "exceptional cases," which can include instances of willful infringement (Compl. ¶18, ¶23).

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

This case appears to present two primary challenges for resolution by the court:

1. An evidentiary question of proof: Given the minimalist nature of the complaint and the foreign domicile of the defendant, a threshold issue will be for the plaintiff to produce evidence demonstrating that the accused products actually contain the specific mechanical locking systems—the "slideable member on a track" of the ’446 patent or the mating "latch parts" of the ’546 patent—as claimed.
2. A legal question of claim scope: The dispute will likely involve a focused battle over claim construction. The central question will be whether the key mechanical terms are interpreted broadly to cover a range of locking functionalities, or narrowly limited to the specific structures depicted in the patents' drawings and descriptions.