DCT
3:25-cv-00099
Fortress Iron LP v. Digger Specialties Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Fortress Iron L.P. (Texas)
- Defendant: Digger Specialties, Inc. (Indiana)
- Plaintiff’s Counsel: Foley & Lardner LLP
- Case Identification: 3:25-cv-00099, N.D. Ind., 01/31/2025
- Venue Allegations: Venue is alleged to be proper in the Northern District of Indiana because Defendant resides in the district, maintains a regular and established place of business there, and has committed the alleged acts of infringement within the district.
- Core Dispute: Plaintiff alleges that Defendant’s vertical cable railing systems infringe two patents related to the design and construction of such barriers, particularly the mechanisms for tensioning the vertical cables.
- Technical Context: The technology concerns outdoor metal railing systems, a common component in residential and commercial construction for decks, balconies, and stairways, where vertical cables are used as infill barriers instead of traditional pickets or balusters.
- Key Procedural History: The complaint notes prior litigation between the same parties involving two parent patents ('707 and '290 Patents). In that case, a court held the patents invalid for failing to name a co-inventor. The current lawsuit asserts two new continuation patents ('’838 and '’735 Patents) that name the previously omitted individual as a co-inventor, which suggests an attempt to cure the defect identified in the earlier proceeding. The judgment in the prior case is currently on appeal.
Case Timeline
| Date | Event |
|---|---|
| 2014-04-14 | Earliest Priority Date for '’838 and '’735 Patents (Provisional App.) |
| 2015-03-31 | Digger introduces original Westbury VertiCable Aluminum Railing |
| 2018-01-01 | Digger begins selling redesigned Westbury VertiCable Railing (approx.) |
| 2021-01-08 | Fortress files prior suit on parent patents ('290 and '707) |
| 2023-05-09 | '’838 Patent Issued |
| 2023-05-12 | Fortress provides Digger notice of '’838 Patent infringement |
| 2024-12-31 | '’735 Patent Issued |
| 2025-01-06 | Fortress provides Digger notice of '’735 Patent infringement |
| 2025-01-31 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,643,838 - “Vertical Cable Rail Barrier,” issued May 9, 2023
The Invention Explained
- Problem Addressed: The patent addresses the construction of barrier railings, which traditionally use vertical pickets or balusters between top and bottom rails (Compl. ¶¶ 6-7; ’838 Patent, col. 1:25-35). The background implies a need for alternative designs, like those using vertical cables, that are both functional and aesthetically refined.
- The Patented Solution: The invention is a vertical cable barrier system featuring a unique bottom rail design. The bottom rail is constructed as a channel that houses an internal member and conceals the tensioning mechanism for the vertical cables (’838 Patent, col. 2:53-65). Specifically, the bottom end of each cable connects to a swage fitting, which is then coupled to a "female adjustable end member" (e.g., a nut) located inside the rail's channel. This allows for tension adjustment while hiding the hardware from view (’838 Patent, Abstract; Figs. 6B, 6D).
- Technical Importance: This design aims to provide a "cleaner" look by concealing the tensioning hardware, which is often exposed in other cable railing systems, thus offering a potential aesthetic advantage in the architectural products market.
Key Claims at a Glance
- Independent Claim 1 is asserted (Compl. ¶ 30).
- The essential elements of Claim 1 include:
- A top rail with a plurality of top through holes.
- A bottom rail forming a channel, which contains an internal member and has both "first" and "second" bottom through holes.
- A rigid support member extending between the rails.
- At least two vertical cables, each with top and bottom swage fittings.
- A "female adjustable end member" for each cable, coupled to the bottom swage fitting and disposed within the bottom rail's channel to adjust cable tension.
- The complaint does not explicitly reserve the right to assert dependent claims.
U.S. Patent No. 12,180,735 - “Vertical Cable Rail Barrier,” issued December 31, 2024
The Invention Explained
- Problem Addressed: The technical problem is identical to that of the '’838 Patent: designing a functional and aesthetically pleasing vertical cable railing system (’735 Patent, col. 1:16-33).
- The Patented Solution: The solution is also a vertical cable rail panel where the tensioning hardware is concealed within the rail structure. The claims of the ’735 Patent describe the tensioning mechanism with slightly different terminology, focusing on a "nut" that couples to a "bottom hollow tubular member" of the cable and engages a "bearing surface" defined by an "internal member" inside the bottom rail (’735 Patent, Abstract; col. 2:50-63). A key feature recited is that the "bottom opening" through which the cable passes has "at least one flat side" (’735 Patent, col. 7:20-22).
- Technical Importance: Like the '’838 patent, this design focuses on concealing tensioning mechanisms to improve the aesthetics of cable railing products.
Key Claims at a Glance
- Independent Claim 1 is asserted (Compl. ¶ 54).
- The essential elements of Claim 1 include:
- A top rail with a cap member and top through holes.
- A bottom rail forming a channel, containing an internal member that defines a bearing surface and a "bottom opening having at least one flat side."
- A rigid support member.
- A vertical cable with top and bottom hollow tubular members swaged to it.
- A "nut" coupled to the bottom hollow tubular member, which adjusts tension by contacting the bearing surface of the internal member.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
- Defendant Digger's "redesigned Westbury VertiCable Aluminum Railing" (the "Accused Product") (Compl. ¶¶ 14, 29, 53).
Functionality and Market Context
- The Accused Product is a vertical cable barrier system used in outdoor construction (Compl. ¶¶ 12, 31). According to the complaint's allegations, it comprises top and bottom aluminum rails, vertical cables that run between them, and a mechanism for tensioning the cables (Compl. ¶¶ 32-43). The complaint alleges the product's tensioning hardware is located within a channel in the bottom rail, where a nut or similar fastener is used to adjust the tension on each vertical cable (Compl. ¶¶ 58-60, 67-68).
- The complaint positions the Defendant as a "direct competitor" of the Plaintiff in the building products market, suggesting the Accused Product competes for the same customers as Plaintiff's own "FortressCable V-Series" railing (Compl. ¶¶ 6, 12).
- No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
'838 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a top rail comprising a top web portion and a pair of top leg portions..., the top web portion defining a plurality of top through holes | The Accused Product includes a top rail with a top web portion, leg portions, and a plurality of top through holes. | ¶32 | col. 3:59-62 |
| a bottom rail comprising a bottom web portion and a pair of bottom leg portions... forming a channel, the bottom web portion defining a plurality of first bottom through holes..., the bottom rail further comprising an internal member disposed within the channel and defining a second bottom through hole | The Accused Product includes a bottom rail with a web portion and leg portions forming a channel, defining first bottom through holes. It also has an internal member within the channel defining a second bottom through hole. | ¶¶33-34 | col. 3:5-12, 26-34 |
| a rigid support member vertically extending between the top rail and the bottom rail | The Accused Product includes a rigid support member extending vertically between the rails. | ¶35 | col. 2:58-60 |
| a first vertical cable... a top end... attached to a hollow tubular shank of a first top swage fitting and a bottom end... attached to a hollow tubular shank of a first bottom swage fitting... the bottom end of the first vertical cable extending through the second bottom through hole | The Accused Product's first vertical cable has top and bottom ends attached to hollow tubular shanks of swage fittings, with the bottom end extending through the specified holes. | ¶¶36-37 | col. 7:26-39 |
| a first female adjustable end member coupled to the first bottom swage fitting and at least a portion of the first female adjustable end member being disposed within the channel... wherein adjusting the first female adjustable end member adjusts a tension in the first vertical cable | The Accused Product includes a first "female adjustable end member" coupled to the bottom swage fitting, with a portion disposed in the channel, which is used to adjust the tension of the first vertical cable. | ¶¶40-41 | col. 8:1-6, 54-57 |
'735 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a top rail comprising a cap member coupled to a top web member, the top web member defining a plurality of top through holes | The Accused Product includes a top rail with a cap member and a web member that defines a plurality of top through holes. | ¶56 | col. 9:1-5 |
| a bottom rail... comprising a bottom web portion and a pair of bottom leg portions... forming a channel... an internal member disposed within the channel and defining a bearing surface... and further defining a bottom opening having at least one flat side | The Accused Product has a bottom rail forming a channel, which contains an internal member that defines a bearing surface and a bottom opening with at least one flat side. | ¶¶57-59 | col. 9:15-25 |
| a rigid support member vertically extending between the top rail and the bottom rail | The Accused Product includes a rigid support member extending vertically between the top and bottom rails. | ¶61 | col. 9:26-30 |
| a vertical cable comprising a cable member, a top hollow tubular member, and a bottom hollow tubular member... wherein the top hollow tubular member is swaged to the cable member... and at least a portion of the top hollow tubular member being larger in size than the one top through hole | The Accused Product has a vertical cable with top and bottom hollow tubular members swaged to it. The top member is larger than the top hole to maintain the cable's position. | ¶¶62, 65-66 | col. 9:31-48 |
| a nut coupled to the bottom hollow tubular member... adjusting the nut adjusts a tension in the vertical cable, a bearing surface of the nut contacting the bearing surface of the internal member | The Accused Product uses a nut coupled to the bottom tubular member. Adjusting this nut tensions the cable, and a surface of the nut contacts the bearing surface of the internal member. | ¶¶67-68 | col. 9:49-55 |
Identified Points of Contention
- Scope Questions: The dispute may turn on the precise definition of claim terms. For the ’838 Patent, a question is whether the accused component constitutes a "female adjustable end member" as construed from the patent. For the ’735 Patent, a significant question is whether the Accused Product's "bottom opening" has "at least one flat side" as required by the claim, and what structural purpose that feature must serve.
- Technical Questions: An evidentiary question will be what proof exists that the components of the Accused Product are constructed and interact in the specific manner claimed. For example, for the ’735 Patent, what evidence demonstrates that the "bearing surface of the nut" makes contact with the "bearing surface of the internal member" to adjust tension, as opposed to another surface or component within the assembly?
V. Key Claim Terms for Construction
For the ’838 Patent:
- The Term: "female adjustable end member"
- Context and Importance: This term is central to the tensioning mechanism of Claim 1. The infringement analysis will depend on whether the specific fastener or component used in the Accused Product falls within the scope of this term. Practitioners may focus on this term because its construction will define the structure of the required tensioning element.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term itself in independent Claim 1 is not expressly limited to a specific shape or type of fastener, suggesting it could encompass any female-threaded component capable of adjustment (’838 Patent, col. 8:1-6).
- Evidence for a Narrower Interpretation: Dependent claims 10 and 11 explicitly narrow this term to a "female threaded member" and a "nut," respectively (’838 Patent, col. 8:26-31). An argument could be made under the doctrine of claim differentiation that the independent claim must be broader than these dependent claims, but the specification's consistent depiction of the element as a nut (e.g., Fig. 5B, element 58) could be used to argue for a narrower construction limited to nut-like structures.
For the ’735 Patent:
- The Term: "bottom opening having at least one flat side"
- Context and Importance: This is a specific geometric limitation applied to the opening in the internal member of the bottom rail. Its presence and function are required for literal infringement. The dispute will likely involve whether the Accused Product has such an opening and, if so, whether it corresponds to the claimed structure.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party might argue that any non-circular opening (e.g., square, hexagonal) inherently has "at least one flat side," and the claim does not require a specific purpose for the flat side (’735 Patent, col. 7:22).
- Evidence for a Narrower Interpretation: The specification does not provide an explicit definition or purpose for this feature. However, a defendant could argue that such a feature is typically intended to engage a corresponding flat surface on a fastener to prevent rotation. The figures illustrate a hexagonal nut (178) used for tensioning (Fig. 11C). A party could argue the "flat side" of the opening must be functional, perhaps to engage one of the flat sides of the nut, and that a merely incidental flat edge on a larger opening is insufficient to meet the limitation.
VI. Other Allegations
- Indirect Infringement: The complaint alleges both induced and contributory infringement for both patents. The inducement claim is based on Defendant actively and knowingly encouraging "end installers and end users" to assemble and use the Accused Product in an infringing manner (Compl. ¶¶ 49, 75). The contributory infringement claim alleges the Accused Product is especially made or adapted for practicing the invention and is not a staple article of commerce with substantial non-infringing uses (Compl. ¶¶ 50, 76).
- Willful Infringement: Willfulness is alleged for both patents. For the '’838 Patent, the claim is based on alleged knowledge of the patent and infringement at least as of May 12, 2023, when Plaintiff's counsel allegedly sent a notice letter (Compl. ¶¶ 46, 48). For the '’735 Patent, willfulness is alleged based on knowledge at least as of January 6, 2025, following a similar notice (Compl. ¶¶ 72, 74).
VII. Analyst’s Conclusion: Key Questions for the Case
The resolution of this case may depend on the court's determination of the following key questions:
A central issue will be one of claim construction and technical correspondence: Can the specific components of the Defendant's redesigned railing be mapped onto the precise language of the asserted claims? This will turn on whether the accused fastener is a "female adjustable end member" ('’838 Patent) and whether the accused rail structure contains a "bottom opening having at least one flat side" ('’735 Patent) as those terms are construed in light of the patent specifications.
A key evidentiary question will be the operational details of the accused product: What factual evidence will be presented to prove or disprove that the accused tensioning mechanism functions by creating contact between the specific surfaces required by the claims, such as the "bearing surface of the nut" and the "bearing surface of the internal member" in Claim 1 of the '’735 Patent?
Looming in the background is a question of legal strategy and preclusion: Given the prior litigation where parent patents were held invalid for an inventorship defect, a key question is how that history will influence this case. While the Plaintiff has seemingly corrected the inventorship on the asserted continuation patents, the technical overlap between the patent families will be a significant factor in the proceedings.