DCT
5:25-cv-01910
Fox Factory Inc v. Suspension Direct Inc
Key Events
Amended Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Fox Factory, Inc. (California)
- Defendant: Suspension Direct, Inc. (California)
- Plaintiff’s Counsel: Hawkinson Yang LLP; Perilla Knox & Hildebrandt LLP
- Case Identification: 5:25-cv-01910, C.D. Cal., 11/10/2025
- Venue Allegations: Venue is alleged to be proper because Defendant resides in the Central District of California and maintains a regular and established place of business in the district.
- Core Dispute: Plaintiff alleges that Defendant’s E-LINK aftermarket suspension products infringe a patent related to electronically controlled damper links for vehicle sway bar systems.
- Technical Context: The technology operates in the high-performance automotive suspension sector, where electronically adjustable sway bars allow vehicles to optimize on-road stability against off-road wheel articulation.
- Key Procedural History: The complaint alleges that Plaintiff provided Defendant with actual notice of the asserted patent via a letter on May 7, 2025, and that Defendant responded on May 21, 2025, denying infringement and declining to cease its allegedly infringing activities. This exchange is cited as the basis for willful infringement.
Case Timeline
| Date | Event |
|---|---|
| 2017-09-29 | U.S. Patent No. 10,981,429 – Earliest Priority Date |
| 2018-09-27 | U.S. Patent No. 10,981,429 – Application Filed |
| 2021-04-20 | U.S. Patent No. 10,981,429 – Issued |
| 2023-02-10 | Defendant's related patent application ('474 Application) filed |
| 2024-03-27 | Defendant allegedly began marketing Accused Product as "patent pending" |
| 2025-05-07 | Plaintiff sent notice letter to Defendant alleging infringement |
| 2025-05-21 | Defendant responded to Plaintiff's letter, denying infringement |
| 2025-11-10 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 10,981,429 - “Electronically Controlled Sway Bar Damping Link”
- Patent Identification: U.S. Patent No. 10,981,429 ("the ’429 Patent"), titled “Electronically Controlled Sway Bar Damping Link,” issued on April 20, 2021.
The Invention Explained
- Problem Addressed: The patent’s background section describes the inherent compromise in conventional vehicle sway bars, which must be stiff enough to reduce body roll during on-road cornering but soft enough to allow for wheel articulation during off-road activities like "rock crawling" (’429 Patent, col. 1:20-43, col. 2:65-col. 3:2). The invention seeks to overcome this compromise with a system that can remotely manipulate its stiffness (’429 Patent, col. 2:50-54).
- The Patented Solution: The invention replaces at least one of the conventional, passive end links of a sway bar with an "electronically controlled damper link" (’429 Patent, Abstract). As illustrated in Figure 1A, these damper links (14L, 14R) connect the ends of the sway bar (12) to the vehicle's suspension. An electronic valve within the damper link can be remotely adjusted to change its damping characteristics, thereby altering the overall stiffness of the sway bar system to suit different driving conditions (’429 Patent, Fig. 1A; col. 2:47-54).
- Technical Importance: This technology allows a vehicle's suspension performance to be dynamically optimized for disparate conditions—such as high-speed cornering and low-speed off-roading—without requiring the driver to perform a manual mechanical adjustment (’429 Patent, col. 8:53-65).
Key Claims at a Glance
- The complaint asserts independent claims 12 and 28 (Compl. ¶¶ 30, 72).
- Independent Claim 12 recites the essential elements of a "sway bar system":
- A sway bar having a first end and a second end;
- A "first electronically controlled damper link" coupled to the sway bar's first end and configured to couple to a vehicle, with this link having "operational damping characteristics which are electronically adjustable"; and
- A "second link" coupled to the sway bar's second end and configured to couple to the vehicle.
- Independent Claim 28 recites a nearly identical system but is directed to "A vehicle and sway bar system" that includes "a vehicle" as a limitation (Compl. ¶72).
- The complaint explicitly asserts dependent claims 19, 20, 21, 22, 23, 24, and 25 and reserves the right to assert others (Compl. ¶30).
III. The Accused Instrumentality
Product Identification
- The accused products are Defendant’s "SDi E-LINK" sway bar link disconnects, particularly when used with the "SDi E-CLIK" electronic suspension control system (collectively, the "Accused E-LINK Products") (Compl. ¶¶ 19, 26, 27). When installed on a vehicle, the complaint refers to the combination as the "Accused Systems" (Compl. ¶4).
Functionality and Market Context
- The Accused E-LINK Products are aftermarket components, primarily for Jeep Wrangler vehicles, marketed as a "revolutionary, new product that can instantly change from being connected to disconnected, automatically" (Compl. ¶¶ 20, 26). The system allegedly integrates with "Terrain Modes" that automatically adjust the link's behavior; for example, in "Trail mode" the link is "unlocked" for off-road articulation but "locks when it senses higher speeds and turns" (Compl. ¶21). The complaint alleges these different operational states ("unlocked," "locked") correspond to distinct, electronically adjustable damping characteristics (Compl. ¶¶ 45, 47-48). The complaint provides an image of the Accused E-LINK Product for the Jeep Wrangler. (Compl. ¶22).
IV. Analysis of Infringement Allegations
'429 Patent Infringement Allegations
| Claim Element (from Independent Claim 12) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a sway bar having a first end and a second end, said second end distal from said first end | The Accused Systems are installed on vehicles that include a sway bar with a first and second end. | ¶37 | col. 1:25-27 |
| a first electronically controlled damper link coupled to said first end of said sway bar and said first electronically controlled damper link configured to be coupled to a first location of a vehicle | The Accused E-LINK Product is an electronically controlled link that is coupled to one end of a vehicle's sway bar and to a location on the vehicle's suspension system. | ¶¶40, 41 | col. 4:26-32 |
| said first electronically controlled damper link having operational damping characteristics which are electronically adjustable | The Accused E-LINK Product, controlled by the E-CLIK system, has at least two operational states ("unlocked" and "locked") that allegedly provide different damping characteristics. | ¶¶42, 45, 47, 48 | col. 3:10-14 |
| a second link coupled to said second end of said sway bar and said second link configured to be coupled to a second location of said vehicle | The Accused E-LINK Products are sold and installed in pairs, such that a second link is coupled to the second end of the sway bar and a second location on the vehicle. | ¶¶56, 57 | col. 5:1-3 |
- Identified Points of Contention:
- Scope Questions: A primary dispute may arise over whether the accused product, marketed as a "disconnect" that switches between "locked" and "unlocked" states (Compl. ¶¶ 20-21), meets the claim limitation of a "damper link having operational damping characteristics which are electronically adjustable." The analysis will question whether having two distinct states (e.g., minimal damping vs. significant damping) constitutes "adjustable" damping characteristics or if it is merely a binary switch outside the claim's scope. An annotated visual from an installation video shows the accused product being coupled to the "first end of sway bar." (Compl. ¶41).
- Technical Questions: The complaint alleges that even in the "locked" or "engaged" state, the accused product is not completely rigid and provides a "level of damping" (Compl. ¶49). The evidentiary basis for this allegation—specifically, whether the product's internal mechanism functions as a fluid-based damper or a purely mechanical lock—will be a critical technical question. Another visual provided in the complaint shows the "damper link" coupled to the vehicle proximate to the "vehicle wheel." (Compl. ¶59).
V. Key Claim Terms for Construction
- The Term: "damper link"
- Context and Importance: The definition of this term is fundamental. Defendant may contend that its E-LINK product is a "disconnect" or a "lock," not a "damper." Plaintiff’s case rests on construing "damper link" to read on a device that offers at least two different levels of resistance to motion, as the complaint alleges the accused product does (Compl. ¶¶ 47-48).
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification describes the invention's purpose as enabling remote input "to manipulate the stiffness of the present sway bar system" (’429 Patent, col. 2:51-54), a functional description that could encompass a switch between a compliant and a rigid state.
- Evidence for a Narrower Interpretation: The patent’s detailed descriptions and figures illustrate conventional hydraulic damper structures with components like pistons, fluid chambers, and valves that meter fluid flow (’429 Patent, Figs. 2A-3B). A party could argue the term should be limited to such traditional damper configurations.
- The Term: "operational damping characteristics which are electronically adjustable"
- Context and Importance: This term's construction will determine whether switching between two states, such as the accused product's alleged "unlocked" and "locked" modes, constitutes an "adjustment" under the patent. Practitioners may focus on this term because if "adjustable" is construed to require a continuous range or multiple discrete steps beyond two, the infringement case could be weakened.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent states that the damping can vary from "fully locked out to a compliant state," which may support the notion that switching between two endpoints is a form of adjustment (’429 Patent, col. 8:37-39).
- Evidence for a Narrower Interpretation: The common meaning of "adjustable" often implies more than a binary on/off function. A party might argue that the specification's focus on altering damping from "soft" to "firm" implies a more nuanced control than a simple lock/unlock mechanism (’429 Patent, col. 3:11-13).
VI. Other Allegations
- Indirect Infringement: The complaint alleges inducement by asserting that Defendant provides installation videos, marketing materials, and technical support that instruct and encourage end-users to install and use the Accused E-LINK Products in an infringing manner (Compl. ¶¶ 81-83). It further alleges contributory infringement, stating the products are material components especially made for infringement with no substantial non-infringing uses (Compl. ¶¶ 93, 95).
- Willful Infringement: The willfulness allegation is based on Defendant's alleged continued infringement after receiving actual notice of the ’429 Patent and the infringement allegations in Plaintiff's letter of May 7, 2025 (Compl. ¶76).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can the claim term "damper link having... electronically adjustable" damping characteristics, which is described in the patent with reference to traditional hydraulic dampers, be construed to cover an accused product marketed as an automatic "disconnect" that switches between "locked" and "unlocked" states?
- A key evidentiary question will be one of technical function: does the accused E-LINK product operate as a true damper by metering fluid to provide variable resistance, as Plaintiff alleges, or does it function as a simple mechanical lock? The resolution may depend on detailed evidence of the product's internal mechanics and performance characteristics in both of its operational states.