DCT
3:25-cv-01399
Cart Source LLC v. Home Depot Inc
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Cart Source LLC (Florida)
- Defendant: The Home Depot, Inc. (Delaware)
- Plaintiff’s Counsel: Malloy & Malloy, P.L.
- Case Identification: 3:25-cv-01399, M.D. Fla., 11/17/2025
- Venue Allegations: Plaintiff alleges venue is proper because Defendant maintains regular and established places of business within the Middle District of Florida and has committed the alleged acts of infringement in the district.
- Core Dispute: Plaintiff alleges that Defendant’s shopping carts are equipped with caster anti-tilt devices that infringe a patent related to preventing shopping carts from being tipped backwards.
- Technical Context: The technology addresses a method used to circumvent electronic anti-theft systems on shopping carts, which often involves tilting a cart to lift a locked wheel off the ground.
- Key Procedural History: The complaint states that Plaintiff provided Defendant with written notice of infringement via a Cease and Desist letter approximately one month before filing suit, to which Defendant allegedly did not respond. This correspondence is cited as the basis for an allegation of willful infringement.
Case Timeline
| Date | Event |
|---|---|
| 2020-08-17 | U.S. Patent No. 11,673,427 Priority Date |
| 2023-06-13 | U.S. Patent No. 11,673,427 Issues |
| 2025-10-15 | Plaintiff places Defendant on written notice of infringement |
| 2025-11-17 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,673,427 - "Caster Anti-Tilt Device"
(Issued June 13, 2023; the “’427 Patent”)
The Invention Explained
- Problem Addressed: The patent’s background section describes a common workaround for shopping cart anti-theft systems, where a user circumvents a locked front wheel by tilting the cart rearward and rolling it on its back wheels (’427 Patent, col. 1:22-25). The patent notes that existing tilt-prevention devices can be dislodged or are complex to manufacture (’427 Patent, col. 1:30-35).
- The Patented Solution: The invention is a mechanical device that mounts onto the axle of a shopping cart’s rear caster wheel. The device features flanges that engage the caster’s frame to prevent the device from rotating around the axle, and two “legs” that extend backward to a crossbar positioned behind the wheel. If the cart is tilted backward, the crossbar contacts the ground, which either lifts the wheel or otherwise obstructs movement, thereby defeating the workaround (’427 Patent, Abstract; col. 3:49-54).
- Technical Importance: The patented design purports to offer a robust and simple mechanical solution to prevent a specific type of product misuse that can lead to retail theft (’427 Patent, col. 1:26-37).
Key Claims at a Glance
- The complaint asserts infringement of independent Claim 1 (Compl. ¶23).
- The essential elements of Claim 1 are:
- An anti-tilt device for a caster comprising a wheel, rotatably mounted in a frame, for rotation about a rotation axis.
- First and second face plates.
- First and second flanges extending from opposing edges of the first face plate, wrapping beside the plate for engagement with the frame.
- First and second flanges extending from opposing edges of the second face plate, wrapping beside the plate for engagement with the frame.
- A "wherein" clause stating that these flanges prevent rotation of the face plates with respect to the caster frame.
- First and second legs extending from the respective face plates.
- A bar extending between the legs across the tread face of the wheel at a defined angle.
- A "wherein" clause stating that each leg includes a defined bend to place the bar at the defined angle.
III. The Accused Instrumentality
Product Identification
The complaint identifies the accused instrumentality as the "caster anti-tilt devices installed on [Defendant's] shopping carts," referred to as the "Accused Device" (Compl. ¶¶16, 18).
Functionality and Market Context
The complaint alleges that Defendant, a national home improvement retailer, uses shopping carts equipped with these devices (Compl. ¶15). The function of the Accused Device, as depicted in photographs, is to prevent a shopping cart from being tipped backwards (Compl. ¶10). An annotated photograph in the complaint shows the Accused Device mounted to a shopping cart caster wheel, with a metal bar positioned behind the wheel's tread (Compl. ¶39).
IV. Analysis of Infringement Allegations
'427 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| first and second face plates | The Accused Device allegedly includes two plate-like structures positioned on either side of the caster wheel, as shown in a photograph. | ¶33 | col. 2:65-66 |
| first and second flanges extending from opposing edges of said... face plate... wrapping beside the... face plate for engagement with the frame | The complaint alleges the Accused Device has flanges that extend from the face plates and engage with the caster frame. The complaint provides photographs showing these flanges wrapping around the frame. | ¶¶34-36 | col. 3:1-19 |
| wherein the... flanges... prevent rotation of the first and second face plates with respect to the caster frame | The complaint alleges that the engagement between the flanges and the caster frame prevents the Accused Device from rotating. | ¶37 | col. 4:1-8 |
| first and second legs extending from the first and second face plates, respectively | A photograph in the complaint shows legs extending backward from the mounting point on the caster. | ¶38 | col. 3:20-24 |
| a bar, extending between the first and second legs across a tread face of said caster wheel... at a defined angle | The complaint includes a photograph of a curved bar extending between the legs and behind the wheel tread, and juxtaposes it with a patent figure to illustrate the alleged angle. | ¶¶39-40 | col. 3:28-39 |
| wherein each of said first and second legs includes a defined bend to place said bar at said defined angle | A photograph points to a bend in the leg of the Accused Device, which allegedly positions the bar at the required angle. | ¶41 | col. 4:9-17 |
Identified Points of Contention
- Scope Questions: The claim requires flanges that "prevent rotation" of the face plates. A potential issue is whether the accused flanges achieve absolute prevention of rotation or merely substantial limitation, which may raise questions of literal infringement versus infringement under the doctrine of equivalents.
- Technical Questions: Claim 1 requires "a defined bend" in each leg. The complaint’s photograph depicts a continuous curve in the leg of the Accused Device (Compl. ¶41). This raises a technical and constructional question as to whether a smooth curve satisfies the "defined bend" limitation.
V. Key Claim Terms for Construction
The Term: "prevent rotation"
- Context and Importance: This functional limitation is central to how the patented device remains correctly oriented. The degree of restriction required by the term "prevent"—whether it means to absolutely stop or merely to substantially hinder—will be critical for determining infringement.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party might argue that in the context of the invention, "prevent" should be given its plain and ordinary meaning of hindering rotation sufficiently to maintain the device's functionality, not necessarily eliminating all possible movement.
- Evidence for a Narrower Interpretation: A party could point to specification language stating the flanges "tightly engage the edges of walls" as evidence that the inventor contemplated a more absolute restriction on movement (’427 Patent, col. 4:4-5).
The Term: "a defined bend"
- Context and Importance: This term describes the structure of the legs that position the anti-tilt bar. Practitioners may focus on this term because the accused device appears to use a continuous curve rather than an angular bend.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification explicitly contemplates alternative structures, stating that "In alternate embodiments, leg 34 could be curved to place bar at the desired offset" (’427 Patent, col. 4:14-16). This language may strongly support construing "bend" to include a curve.
- Evidence for a Narrower Interpretation: A party could argue that the primary embodiment describes the bend as being "formed by forming each leg 34 as two rectangular portions offset by an angle α" (’427 Patent, col. 4:10-12). This could be used to argue that "bend" implies a more discrete, angular feature distinct from a continuous curve.
VI. Other Allegations
Willful Infringement
The complaint alleges willful infringement based on Defendant's alleged failure to cease its infringing conduct after receiving a cease and desist letter on or about October 15, 2025 (Compl. ¶¶18, 43, 45). Plaintiff characterizes Defendant’s continued use of the Accused Device as "egregious conduct" (Compl. ¶45).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of claim construction: can the term "a defined bend," which is described in one embodiment as two distinct portions offset by an angle, be construed to cover the continuous curve shown in the photographs of the accused device, especially given the specification's statement that the leg "could be curved"?
- A key factual question will be one of functional performance: does the evidence show that the flanges on the accused device "prevent rotation" of the face plates, as required by the claim, or do they merely limit rotation to a degree that falls short of the claimed function, potentially pushing the analysis toward the doctrine of equivalents?