Keystone Retaining Wall Systems LLC v. Oldcastle Architectural Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Keystone Retaining Wall Systems, LLC (Minnesota)
  • Defendant: Oldcastle Architectural, Inc. (Delaware), Anchor Wall Engineering, LLC (Minnesota), and Anchor Wall Systems, Inc. (Minnesota)
  • Plaintiff’s Counsel: DeWitt LLP; Colucci & Gallaher, P.C.
• Case Identification: 0:19-cv-00329, D. Minn., 02/11/2019
• Venue Allegations: Venue is asserted based on Defendants' alleged acts of infringement within the District of Minnesota and their business operations, including offering services and placing goods into the stream of commerce intended for sale in Minnesota.
• Core Dispute: Plaintiff alleges that Defendants’ "Diamond Pro PS" brand of segmental retaining wall blocks infringes a patent related to the structural design of interlocking concrete blocks.
• Technical Context: The lawsuit concerns technology in the field of civil engineering and construction, specifically the design of precast, interlocking concrete blocks used to build mortar-free retaining walls.
• Key Procedural History: The complaint alleges that Plaintiff informed Defendants on October 12, 2018, that the accused product infringed the patent-in-suit, an event that forms the basis for the willfulness allegation.

Case Timeline

Date	Event
2001-06-07	’561 Patent Priority Date
2003-09-09	’561 Patent Issue Date
2018-10-12	Plaintiff allegedly notified Defendants of infringement
2019-02-11	Complaint Filing Date

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

A. U.S. Patent No. 6,615,561 - "Retaining Wall Block"

• Patent Identification: U.S. Patent No. 6,615,561, "Retaining Wall Block", issued September 9, 2003.

The Invention Explained

• Problem Addressed: The patent describes a need to improve the structural strength of segmental retaining wall blocks and facilitate easier, more efficient construction methods (’561 Patent, col. 2:30-36). Prior art block designs were susceptible to breakage at corner segments, and their assembly could be cumbersome, sometimes requiring blocks to be flipped over during installation (’561 Patent, col. 2:25-29, col. 5:40-45).
• The Patented Solution: The invention is a retaining wall block with a specific arrangement of pin holes and "pin receiving cavities" that extend through the entire thickness of the block. A key aspect of the design is that these cavities are positioned "substantially outside of block corner segments" (’561 Patent, Abstract). This placement is intended to strengthen the block by moving openings away from structurally vulnerable corners, while the through-block cavities simplify installation by allowing installers to see and align pins from above (’561 Patent, col. 5:40-45; col. 6:1-5).
• Technical Importance: This design purports to offer a stronger, lighter, and more installer-friendly block, addressing persistent issues of structural integrity and construction efficiency in the segmental retaining wall industry (’561 Patent, col. 10:26-42).

Key Claims at a Glance

• The complaint asserts infringement of at least claims 19, 20, and 21 (Compl. ¶16). Claim 19 is an independent claim.
• Independent Claim 19 (Essential Elements):
  • A retaining wall block for use in constructing a wall with at least first and second courses of blocks connected by pins.
  • The block comprises a top surface, a bottom surface, side surfaces, a front face, and a rear face, defining a body portion, a head portion, and a connecting neck portion.
  • The block is symmetrical about a vertical plane of symmetry.
  • The block includes first and second pin holes opening into the top surface.
  • The block includes first and second pin receiving cavities extending through the body portion from the top surface to the bottom surface.
  • The first pin receiving cavity and first pin hole are on a first side of the plane of symmetry.
  • The second pin receiving cavity and second pin hole are on a second side of the plane of symmetry.
  • The first pin hole is located "nearer the first side surface than the first pin receiving cavity."
  • The second pin hole is located "nearer the second side surface than the second pin receiving cavity."
• The complaint does not explicitly reserve the right to assert other claims, but the prayer for relief seeks a judgment that Defendants infringed "one or more of the claims of the '561 patent" (Compl. ¶B, p. 5).

III. The Accused Instrumentality

A. Product Identification

• The accused products are retaining wall blocks advertised and sold under the name "Diamond Pro PS" (Compl. ¶14, ¶15).

B. Functionality and Market Context

• The complaint alleges that the Diamond Pro PS blocks are used in the design and construction of segmental block retaining wall systems (Compl. ¶12, ¶13). It further alleges that defendants Anchor Wall Systems and Anchor Wall Engineering created "details... to assist in manufacturing, marketing, and sale of the Diamond Pro PS," suggesting these blocks are part of a larger system sold to the public (Compl. ¶16). The complaint asserts that Defendant Oldcastle manufactures these blocks in Minnesota and nationwide (Compl. ¶12).

IV. Analysis of Infringement Allegations

The complaint references an attached "Exhibit 3" containing a chart that compares the patent claims to the accused "Diamond Pro PS details" (Compl. ¶16). However, this exhibit was not provided with the filed complaint. The infringement theory must therefore be inferred from the complaint's narrative allegations.

The core of the infringement allegation is that the "Diamond Pro PS" blocks are "described by one or more claims of the ’561 patent" and specifically infringe at least claims 19, 20, and 21 (’561 Patent; Compl. ¶14-16). This implies that Plaintiff contends the Diamond Pro PS block possesses the specific structural and geometric features recited in those claims, including the relative positioning of its pin holes and through-block pin receiving cavities with respect to the block's side surfaces and plane of symmetry. No probative visual evidence provided in complaint.

• Identified Points of Contention:
  • Technical Questions: A primary factual dispute will likely concern whether the physical geometry of the Diamond Pro PS block maps onto the specific spatial limitations of the asserted claims. For example, does the accused block feature pin holes that are demonstrably "nearer" a side surface than a corresponding pin receiving cavity, as required by claim 19?
  • Scope Questions: The case may involve disputes over the interpretation of claim terms that define the block's structure. A central question could be whether the accused block's features, such as its voids or openings, function as the claimed "pin receiving cavities" and are located relative to the "side surfaces" in the manner claimed.

V. Key Claim Terms for Construction

• The Term: "corner portions" (from independent claim 1, which provides context for the invention's goals).

• Context and Importance: The patent’s summary states that the "pin receiving cavities being positioned such that no substantial portion of the cavities lies within the first and second corner portions" is a key feature for strengthening the block (’561 Patent, col. 2:57-64). The definition of this term is therefore critical for determining whether the placement of cavities in an accused product achieves the patented solution or falls outside the claim scope. Practitioners may focus on this term because its definition establishes the boundary between the invention and prior art that suffered from weak corners.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification does not provide a precise definition, which could support a more functional interpretation based on the areas of a block generally understood to be corners susceptible to damage.
  • Evidence for a Narrower Interpretation: The term is defined structurally by reference to the intersection of planes derived from the block's neck and body portions (’561 Patent, col. 2:54-59). An argument for a narrower construction would likely tie the term strictly to the geometric relationships shown in Figure 1 and described in the specification (e.g., corner segments 56a, 58a).

• The Term: "nearer the first side surface than the first pin receiving cavity" (from independent claim 19).

• Context and Importance: This is a precise relational limitation in the asserted independent claim 19. The infringement analysis will depend entirely on the physical measurements of the accused product relative to the points of reference established by this term. A dispute over how to measure the "distance" from a surface or a cavity (e.g., from its edge, its center) could be dispositive.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: A party might argue the term should be understood in the context of the overall layout, where the pin holes are visibly closer to the outer edge of the block than the cavities, without requiring a specific method of measurement.
  • Evidence for a Narrower Interpretation: The figures, such as Figure 1, provide a clear visual representation of this relationship, showing pin hole (17) located laterally outward from pin receiving cavity (19) (’561 Patent, Fig. 1). A narrow interpretation would insist on this specific spatial arrangement.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that all Defendants "induced and/or contributed to the manufacture, use, offer to sell, or sale" of the infringing blocks (Compl. ¶14, ¶15). The factual basis for this is the allegation that Defendants Anchor and Anchor Engineering created "details... to assist in manufacturing, marketing, and sale of the Diamond Pro PS," which may be construed as materials that instruct or encourage infringement by others (Compl. ¶16).
• Willful Infringement: The willfulness claim is based on alleged pre-suit knowledge. The complaint asserts that Defendants were "informed by Keystone on [October 12, 2018] that the Diamond Pro PS system infringed the ’561 patent" and yet "continued to manufacture, use, offer to sell, and/or sell the infringing product" (Compl. ¶19).

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

The resolution of this dispute will likely depend on the court’s determination of two central issues:

1. A core issue will be one of claim construction: How are the structural and relational terms of the claims, such as "corner portions" and the requirement that a pin hole be "nearer" a side surface than its corresponding cavity, to be defined? The patent’s emphasis on locating cavities away from vulnerable corners may lead to a construction that is heavily influenced by this stated technical benefit.

2. A key evidentiary question will be one of factual correspondence: Assuming a construction is reached, does the precise physical geometry of the accused "Diamond Pro PS" block meet every limitation of the asserted claims? This will be a fact-intensive inquiry likely revolving around measurements and expert testimony comparing the accused product to the patent's claims and figures.