DET Diesel Emission Tech LLC v. DPF Alternatives LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: DET Diesel Emission Technologies, LLC (Texas)
  • Defendant: DPF Alternatives, LLC, et al. (Colorado, et al.)
  • Plaintiff's Counsel: Cunningham Swaim, LLP; Jackson Walker LLP
• Case Identification: 3:26-cv-00916, N.D. Tex., 03/20/2026
• Venue Allegations: Venue is asserted based on other pending litigation initiated by Defendant DPF Alternatives against Plaintiff in the same district, as well as general federal venue statutes.
• Core Dispute: Plaintiff alleges that Defendants' "New Core" systems and services, used for replacing the filter cores within diesel emission control devices, infringe a patent covering a specific process for performing this replacement.
• Technical Context: The technology concerns the refurbishment of diesel particulate filters (DPFs), a critical component in modern diesel engines for controlling soot emissions, by enabling the replacement of the internal filter core rather than the entire housing assembly.
• Key Procedural History: The complaint alleges a prior business relationship where some Defendants licensed Plaintiff's "Recoring" technology under confidentiality agreements, which Plaintiff claims was then used to create the competing and allegedly infringing "New Core" technology. The patent-in-suit is a divisional of a parent patent that is the subject of separate, ongoing litigation between the parties.

Case Timeline

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

U.S. Patent No. 12,502,663 - "Process for Replacing a Core of Diesel Emission Control Device"

• Patent Identification: U.S. Patent No. 12,502,663, "Process for Replacing a Core of Diesel Emission Control Device," issued December 23, 2025 (the "'663 Patent").

The Invention Explained

• Problem Addressed: The patent addresses the need for an "efficient and economical means to refurbish a diesel emission control device (DECD)" '663 Patent, col. 3:4-7 Replacing the entire DECD unit is costly, and the invention provides a method to replace only the internal filter core '663 Patent, col. 1:15-23
• The Patented Solution: The invention is a specific, multi-step process for inserting a new filter core into an existing DECD housing using a press station '663 Patent, abstract Key steps include placing a "spacer" on the press's working platform to set the correct insertion depth, coupling a "stuffing funnel" to the housing to guide the new core, pressing the new core (which has been wrapped in a matting) through the funnel until it "abuts the spacer," and finally removing the spacer from inside the housing '663 Patent, col. 12:31-44 This combination of components and steps is designed to ensure precise and secure installation of the replacement core '663 Patent, col. 10:1-4
• Technical Importance: This process-based approach allows repair facilities to service a wide range of emission control devices with a single system, reducing inventory requirements and the overall cost of refurbishment compared to full unit replacement Compl. ¶¶24-25

Key Claims at a Glance

• The complaint asserts infringement of independent claim 4 and dependent claims 5-10 Compl. ¶¶49-82
• Independent Claim 4 consists of the following essential process steps:
  • providing a core press station having a working platform;
  • placing a spacer onto the working platform;
  • aligning the DECD housing over the spacer;
  • coupling a stuffing funnel to the DECD housing;
  • wrapping the replacement core with a matting;
  • aligning the replacement core with the DECD housing;
  • pressing the replacement core through the stuffing funnel and into the DECD housing until it abuts the spacer; and
  • removing the spacer from within the DECD housing. '663 Patent, col. 12:31-44
• The complaint alleges infringement of "one or more claims" of the "'663 Patent" Compl. ¶49

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are two versions of a system, "New Core 1" and "New Core 2," and the associated processes for using them to replace diesel particulate filter cores Compl. ¶45 These are collectively termed the "Accused Products" Compl. ¶45

Functionality and Market Context

The Accused Products are systems, including a press and associated tooling, marketed and provided by Defendant DPF Alternatives to its franchisees and affiliates for servicing and "recoring" DPF units (Compl. ¶41; Compl. ¶42; Compl. ¶43; Compl. ¶44; Compl. ¶45). The complaint provides a screenshot from a defendant's website showing the "New Core 1" press system, which is described as a tool for installing replacement filter cores Compl. p. 11 Marketing materials state that an "Alignment tool/Funnel guides the filter into the housing seamlessly" Compl. p. 28 The complaint alleges that these products and services are part of a nationwide partnership between the defendants to compete with the Plaintiff's "Recore" technology Compl. p. 9 Compl. ¶35 A photograph from a trade show displays the "New Core 2" system with a DECD housing positioned on its press station Compl. p. 12

IV. Analysis of Infringement Allegations

'663 Patent Infringement Allegations

Identified Points of Contention

• Scope Questions: The complaint alleges that the Accused Products infringe a process claim Compl. ¶52 A threshold question may be whether the defendants themselves perform all steps of the claimed method (direct infringement) or are liable for inducing their customers/franchisees to perform the steps (indirect infringement). The complaint includes counts for both theories Compl. ¶39 Compl. ¶86
• Technical Questions: A factual question may be whether the component identified as a "spacer" in the complaint's annotated photograph Compl. p. 20 functions to stop the pressing step upon abutment, as required by the claim. The final step, "removing the spacer," is alleged on "information and belief" Compl. ¶61, which suggests a potential evidentiary challenge for the plaintiff to prove this step is actually performed in the accused process.

V. Key Claim Terms for Construction

The Term: "spacer"

• Context and Importance: The "spacer" is a critical element that physically stops the insertion of the replacement core at a precise depth '663 Patent, col. 12:41-43 The infringement allegation hinges on identifying a component of the accused system as this "spacer" Compl. p. 20 Practitioners may focus on this term because its construction will determine whether a variety of jigs and depth-setting tools can meet the limitation, or if it is restricted to a more specific structure.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language recites "placing a spacer onto the working platform," suggesting it can be a distinct, movable component '663 Patent, col. 12:35-36 The patent summary also describes it as "a spacer connected to the working platform," which could be read to cover a wide range of connected or placed objects '663 Patent, col. 1:65-col. 2:1
  • Evidence for a Narrower Interpretation: The patent specification links the "spacer" to a specific function: it is selected "based on the overhang distance" to ensure proper final positioning '663 Patent, col. 2:42-44 '663 Patent, col. 12:51-53 A defendant may argue the term is limited to the separate, disc-like embodiments shown in Figure 4C, which are explicitly presented as "a plurality of spacers" '663 Patent, Fig. 4C '663 Patent, col. 3:35-36

The Term: "stuffing funnel"

• Context and Importance: This term describes the component that guides the new core into the housing '663 Patent, col. 12:37-38 The complaint identifies a corresponding part in the accused system Compl. p. 26, and its definition is important for determining if the accused part performs the claimed function in the claimed way.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim requires "coupling a stuffing funnel to the DECD housing" '663 Patent, col. 12:37-38 The marketing materials for the accused product refer to an "Alignment tool/Funnel" that "guides the filter into the housing" Compl. p. 28, language which aligns with a broad functional definition.
  • Evidence for a Narrower Interpretation: The specification shows the "stuffing funnel" as a distinct, tapered, ring-like structure '663 Patent, Fig. 4B A defendant could argue that the term is implicitly limited to a structure that not only guides the core but also compresses the matting during insertion, a function suggested by its shape and name.

VI. Other Allegations

Indirect Infringement

The complaint alleges that Defendant DPF Alternatives induces infringement by providing the Accused Products, training, and other resources to its affiliates and franchisees with the knowledge and intent that they will use them to perform the patented process Compl. ¶¶88-89 It also pleads contributory infringement, alleging the Accused Products are not staple articles of commerce and are especially adapted for this infringing use Compl. ¶91

Willful Infringement

Willfulness is alleged based on knowledge of the "'663 Patent" as of its issue date, December 23, 2025 Compl. ¶83 The complaint asserts that Defendants have continued to infringe despite an "objectively high likelihood that [their] actions constituted infringement" Compl. ¶83

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

• A core issue will be one of process evidence: given that infringement of the asserted method claim requires performance of every step, a key evidentiary question is what proof the plaintiff can offer that the accused process, as practiced by defendants or their franchisees, includes the final, discrete step of "removing the spacer from within the DECD housing."
• A second central issue will be one of definitional scope: can the claim term "spacer", which the patent illustrates as a separate, selectable disc, be construed to cover the integrated jig or platform component of the accused system, or is there a fundamental structural and functional distinction between them?
• Finally, the case may turn on a question of intent and history: how will the alleged prior business relationship, which purportedly gave Defendants access to Plaintiff's confidential technology Compl. ¶¶31-35, influence the court's view of intent for the willfulness and indirect infringement claims? This context raises the question of whether the accused system was independently developed or derived from Plaintiff's own patented methods.