DCT
1:25-cv-00143
Klein Tools Inc v. Milwaukee Electric Tool Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Klein Tools, Inc. (Delaware)
- Defendant: Milwaukee Electric Tool Corporation (Delaware)
- Plaintiff’s Counsel: Richards, Layton, & Finger, P.A.; Kirkland & Ellis LLP
- Case Identification: 1:25-cv-00143, D. Del., 02/04/2025
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant is a Delaware corporation.
- Core Dispute: Plaintiff alleges that Defendant’s BOLT™ brand safety helmet system infringes a patent for modular helmets with interchangeable accessory mounts, and that Defendant's Glow Fish Tape systems infringe two patents related to luminescent fish tapes housed in transparent cases.
- Technical Context: The technologies at issue relate to personal protective equipment and tools used by electricians and other tradespeople, specifically safety hard hats and fish tapes for pulling wires through conduits.
- Key Procedural History: The complaint alleges that Defendant had pre-suit knowledge of the application that matured into the ’327 Patent (safety helmet) as early as October 2020, asserting that Defendant cited the application as prior art in multiple Information Disclosure Statements during the prosecution of its own patents and received office action rejections based on the ’327 Patent.
Case Timeline
| Date | Event |
|---|---|
| 2018-01-26 | Priority Date for ’327 Patent |
| 2019-07-01 | Klein Tools launches its new-generation hard hat system (approx. date) |
| 2019-11-26 | Priority Date for ’209 and ’573 Patents |
| 2020-10-29 | Milwaukee allegedly files first IDS citing ’327 Patent application |
| 2020-12-17 | Klein Tools launches 20-Foot Glow Fish Tape System |
| 2021-08-30 | Milwaukee allegedly files second IDS citing ’327 Patent application |
| 2021-12-06 | Milwaukee launches its BOLT hard hat system |
| 2022-03-31 | Milwaukee allegedly files third IDS citing ’327 Patent application |
| 2022-09-27 | ’327 Patent issues |
| 2023-02-14 | Klein Tools launches 40' Glow in the Dark Fish Tape System |
| 2023-08-01 | ’209 Patent issues |
| 2024-01-24 | Milwaukee patent application allegedly rejected over ’327 Patent |
| 2025-01-07 | ’573 Patent issues |
| 2025-02-04 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,452,327 - "Safety Helmet", issued Sep. 27, 2022
The Invention Explained
- Problem Addressed: The patent identifies challenges with existing methods for mounting accessories, such as headlamps, onto safety helmets. It notes that elastic bands can slip and that integrated batteries make headlamps heavy, causing the helmet to tilt forward, while separate battery packs require cumbersome wires (’327 Patent, col. 1:26-58).
- The Patented Solution: The invention proposes a safety helmet with standardized front and rear mounting points, referred to as "receptacles." These receptacles are described as having an "identical construction," which allows various accessories—like a headlamp, camera, or battery pack—to be releasably and interchangeably mounted on either the front or the back of the helmet, providing modularity and better weight distribution (’327 Patent, Abstract; col. 2:1-6).
- Technical Importance: This system provides a stable, integrated platform for helmet accessories, aiming to enhance user convenience and safety by allowing weight balancing and eliminating the need for unreliable bands or snag-prone external wires (’327 Patent, col. 4:31-40).
Key Claims at a Glance
- The complaint asserts independent claim 1 (Compl. ¶36).
- Essential elements of claim 1 include:
- An outer shell with a front side, a rear side, and a brim.
- A front receptacle with an external slot and a protruding nub located above the brim.
- A rear receptacle with an additional external slot, where the front and rear receptacles are of "identical construction."
- An accessory device with a mating receptacle that is "releasably mountable onto each of the front receptacle and the rear receptacle."
U.S. Patent No. 11,713,209 - "Glow Fish Tape System", issued Aug. 1, 2023
The Invention Explained
- Problem Addressed: The patent background explains that in low-light environments, such as inside walls or conduits, it is difficult for an electrician to see the end of a fish tape used for pulling wires. While lighted tips exist, they are not effective if the tip has already moved past the target opening (’209 Patent, col. 1:26-37).
- The Patented Solution: The invention is a fish tape system where the tape itself is made of or coated with a luminescent material that glows after being exposed to light. Crucially, the case that stores the coiled tape is at least partially "transparent," which allows light to pass through and "charge" the luminescent material while the tape is stored inside (’209 Patent, Abstract; col. 2:40-47).
- Technical Importance: This approach makes the entire visible length of the fish tape glow, improving its visibility in dark workspaces and making it easier for users to locate and manipulate the tape (’209 Patent, col. 1:26-37).
Key Claims at a Glance
- The complaint asserts independent claim 6 (Compl. ¶68).
- Essential elements of claim 6 include:
- A fish tape with a luminescent material that emits light after being energized.
- A donut-shaped case with a storage compartment for the tape.
- A handle mounted to slide within an annular opening of the case.
- A portion of the case must be "transparent to allow the luminescent material to be energized by light passing through the portion."
Multi-Patent Capsule
- Patent Identification: U.S. Patent No. 12,187,573, “Glow Fish Tape System,” issued Jan. 7, 2025 (Compl. ¶27).
- Technology Synopsis: As a continuation of the application for the ’209 Patent, this patent shares the same core technology. It describes a fish tape system comprising a tape with luminescent properties and a case designed to be at least partially transparent. This design allows the tape to be energized by an external light source while coiled in the case, thereby glowing for enhanced visibility during use in dark environments (’573 Patent, Abstract; Compl. ¶29).
- Asserted Claims: At least independent claim 6 (Compl. ¶89).
- Accused Features: The complaint accuses Milwaukee's Glow Fish Tape systems, which are alleged to feature a luminescent tape and a case with "open slots for easy recharging" (Compl. ¶¶33, 77).
III. The Accused Instrumentality
Product Identification
The accused instrumentalities are the Milwaukee BOLT™ System, which includes safety helmets, hard hats, and a line of compatible accessories, and the Milwaukee Glow Fish Tape Systems (Compl. ¶¶31, 33).
Functionality and Market Context
- The complaint alleges the Milwaukee BOLT™ System is marketed as a versatile platform that allows users to "secure accessories simultaneously" on a single hard hat (Compl. ¶32). The system is based on front and rear mounting points on the helmet, which are allegedly designed to accept a range of accessories, including headlamps, face shields, and visors (Compl. ¶31). The complaint highlights promotional material stating that a headlamp mount "secures into the Front or Rear BOLT™ Mount," suggesting interchangeability (Compl. ¶52). A product page for the accused headlamp mount shows the accessory securing to both the front and rear of a helmet (Compl. p. 12, Ex. 14).
- The Milwaukee Glow Fish Tape Systems are advertised as providing a "bright glow in low light applications" (Compl. ¶33). The complaint alleges that the key infringing functionality is found in the case design, which includes "open slots throughout the case [that] allow light to easily charge the tape resulting in a bright glow in the dark" (Compl. ¶76). A screenshot from the accused product's webpage lists "Open slots for easy recharging" as a key feature (Compl. p. 21, Ex. 11).
IV. Analysis of Infringement Allegations
’327 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| an outer shell adapted to be worn by a user... having an exterior surface defining a front side, a rear side, and a brim... | The accused BOLT™ hard hats and helmets comprise an outer shell with a front, rear, and a brim (Compl. ¶¶31, 50-51). | ¶50 | col. 4:43-48 |
| a front receptacle having an external slot extending upwardly along the front side on the exterior surface of the outer shell above the brim and a protruding nub... | The accused helmets allegedly have a front "BOLT™ Mount" for accessories, located above the brim (Compl. ¶52). The complaint does not specify the functionality corresponding to the "protruding nub." | ¶52 | col. 4:9-11 |
| a rear receptacle having an additional external slot... wherein the front receptacle and the rear receptacle are of identical construction... | The accused helmets allegedly feature a rear "BOLT™ Mount" that is functionally identical to the front mount, allowing accessories to be secured "into the Front or Rear BOLT™ Mount" (Compl. ¶52, citing Ex. 14). | ¶52 | col. 2:1-3 |
| an accessory device having a mating receptacle formed thereon... being selectively engageable within each of the external slot... such that the accessory device is releasably mountable onto each of the front receptacle and the rear receptacle... | The complaint identifies accessories like the "BOLT™ Low-Profile Headlamp Mount" as being designed to releasably secure to both the front and rear mounts of the accused helmets (Compl. ¶52). | ¶52 | col. 4:51-64 |
- Identified Points of Contention:
- Scope Questions: A central dispute may concern the claim term "identical construction." The court will need to determine whether this requires the front and rear receptacles to be physically and geometrically identical, or if functional identity—the ability to accept the same accessory—is sufficient.
- Technical Questions: What evidence does the complaint provide that the accused helmet's locking mechanism includes a "protruding nub" as required by the claim? The complaint's allegations are centered on product-level descriptions and may require discovery to substantiate the specific mechanical engagement. An image from the accused headlamp's operator's manual depicts assembly instructions for mounting the accessory (Compl. p. 15, Ex. 20).
’209 Patent Infringement Allegations
| Claim Element (from Independent Claim 6) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a fish tape having a length... comprising a luminescent material that emits light after being energized by exposure to a light source... | The accused products are marketed as "Glow Fish Tape" systems that provide a "bright glow in the dark" (Compl. ¶¶33, 76). An image shows the product glowing in a dark space (Compl. p. 4). | ¶76 | col. 3:21-25 |
| a donut shaped case having a pair of sidewalls... to define a fish tape storage compartment... | The accused products feature a donut-shaped case that stores the coiled fish tape (Compl. ¶33). A product brochure illustrates the coiled tape inside the case (Compl. p. 22, Ex. 25). | ¶33 | col. 3:31-40 |
| a handle engaged with the fish tape and mounted to slide within the annular opening of the case... | The accused products feature a "multi-position handle" (Compl. ¶76). The complaint does not specify whether this handle slides as required by the claim. | ¶76 | col. 4:1-6 |
| wherein at least a portion of the case is transparent to allow the luminescent material to be energized by light passing through the portion. | The accused product's case is alleged to have "open slots" that "allow light to easily charge the tape," which Plaintiff alleges satisfies the "transparent" limitation (Compl. ¶76). | ¶76 | col. 2:44-47 |
- Identified Points of Contention:
- Scope Questions: The primary dispute may be the interpretation of "transparent." The court will have to decide if this term can encompass physical "open slots" that allow light to pass through, as alleged for the accused product, or if it is limited to a see-through material as described in embodiments in the patent.
- Technical Questions: Does the accused product's "multi-position handle" function in a way that meets the claim limitation of a handle "mounted to slide"? The complaint provides limited evidence on the specific operation of the handle.
V. Key Claim Terms for Construction
’327 Patent, Claim 1: "identical construction"
- Context and Importance: This term is critical because the patent's asserted novelty rests on the interchangeability of accessories between the front and rear of the helmet. The infringement analysis for the BOLT™ System, which is marketed on its modularity, will depend heavily on whether its front and rear mounts are deemed to have "identical construction."
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification, when describing an embodiment, states that the rear slot is "substantially identical to the front tapered receiver slot" (’327 Patent, col. 4:37-39). A party could argue this suggests the inventor contemplated functional equivalence rather than strict physical identity.
- Evidence for a Narrower Interpretation: The claim itself, as well as the abstract, uses the precise term "identical construction" without qualification (’327 Patent, col. 2:2-3; col. 8:30-31). A party could argue this requires the front and rear receptacles to be geometrically and materially the same, not merely compatible with the same accessory.
’209 Patent, Claim 6: "transparent"
- Context and Importance: The patent's point of novelty is the ability to charge the luminescent tape while it is stored in its case. The infringement case hinges on whether the "open slots" in the accused Milwaukee case meet the "transparent" limitation. Practitioners may focus on this term because it presents a classic dispute between a functional definition and a structural one.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim requires the case to be "transparent to allow the luminescent material to be energized." Plaintiff may argue that any feature, including a hole, that achieves this purpose falls within the scope. The function, not the specific structure, is what is claimed.
- Evidence for a Narrower Interpretation: The specification's detailed description discusses making the case components from "transparent" material like polycarbonate, suggesting the term refers to the property of a material, not the absence of material (’209 Patent, col. 3:56-62). Defendant may argue that "open slots" are openings, not a "transparent" portion of the case itself.
VI. Other Allegations
- Indirect Infringement: The complaint alleges inducement of infringement for all patents. For the ’327 Patent, it cites Defendant’s promotional materials and operator's manuals that allegedly instruct users to attach accessories to the front and rear mounts (Compl. ¶¶56-57). For the ’209 and ’573 Patents, it cites advertising, product pages, and brochures that highlight the "easy recharging" of the glow tape through the case's open slots (Compl. ¶¶74, 76-78).
- Willful Infringement: The complaint alleges willful infringement for all patents. For the ’327 Patent, the allegations are particularly specific, asserting Defendant had pre-suit knowledge of the patent-pending application by repeatedly citing it as prior art during the prosecution of its own patent applications, beginning as early as October 2020, and by having its own applications rejected over the issued ’327 Patent (Compl. ¶¶40-44). For the ’209 and ’573 Patents, the allegations are based on knowledge at least as of the filing of the complaint (Compl. ¶¶72, 93).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope for the '327 Patent: can the term "identical construction," as applied to the helmet's front and rear accessory receptacles, be construed to cover mounts that are functionally interchangeable but may not be physically identical?
- A second key issue of definitional scope will arise for the '209 and '573 Patents: does the claim term "transparent," in the context of allowing light to energize a fish tape, read on the "open slots" of the accused product's case, or is its meaning limited to a see-through material?
- A critical question for willfulness and potential enhanced damages will be evidentiary: what was the extent of Defendant's pre-suit knowledge of the '327 Patent? The court will likely scrutinize the specific allegations that Defendant cited the patent application as prior art against its own inventions, which Plaintiff will argue demonstrates a deliberate decision to proceed with its product despite awareness of Klein Tools' intellectual property.