Caswell Products LLC v. Nostalgia Products LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Caswell Products LLC (Minnesota)
  • Defendant: Nostalgia Products LLC (Florida/Wisconsin) and Nostalgia Products Group LLC (Delaware/Wisconsin)
  • Plaintiff's Counsel: Husch Blackwell LLP
• Case Identification: 1:26-cv-01235, E.D. Wis., 07/13/2026
• Venue Allegations: Venue is alleged to be proper in the Eastern District of Wisconsin because Defendants have committed acts of infringement in the district, a substantial part of the events giving rise to the claim occurred there, and Defendant Nostalgia Products Group LLC has a principal and established place of business in the district.
• Core Dispute: Plaintiff alleges that Defendant's microwave plate cover infringes a patent related to a reusable splatter cover featuring magnets for storage inside a microwave oven.
• Technical Context: The technology addresses common frustrations with microwave cooking, namely food splatter and the inconvenient storage of bulky conventional covers.
• Key Procedural History: The complaint alleges a notable history between the parties, including a prior license agreement for the patent-in-suit, which Defendant Nostalgia Products LLC ("Nostalgia") entered into after receiving a notice of infringement and later unilaterally terminated. Plaintiff alleges that after termination, Nostalgia began selling the currently accused product, which Plaintiff contends is substantially similar to the previously licensed product and remains within the patent's scope.

Case Timeline

Date	Event
2016-06-13	U.S. Patent No. 10,582,802 Priority Date
2020-03-10	U.S. Patent No. 10,582,802 Issued
2022-01-XX	Caswell notifies Nostalgia of infringement
2022-04-08	License Agreement between Caswell and Nostalgia becomes effective
2023-05-31	Nostalgia unilaterally terminates the License Agreement
2023-11-27	Caswell purchases the Accused Product
2023-12-14	Caswell sends post-termination infringement letter to Nostalgia
2026-07-13	Complaint Filing Date

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

U.S. Patent No. 10,582,802 - "Microwave Splatter Cover or Enclosure"

• Patent Identification: U.S. Patent No. 10,582,802 ("the '802 Patent"), "Microwave Splatter Cover or Enclosure," issued March 10, 2020.

The Invention Explained

• Problem Addressed: The patent's background describes drawbacks of existing microwave splatter solutions. Paper towels can fall into food, and conventional plastic covers can become hot, cause food to get soggy from trapped steam, and occupy valuable cabinet or drawer space when not in use '802 Patent, col. 1:20-39 Compl. ¶22
• The Patented Solution: The invention is a reusable microwave splatter cover that solves the storage problem by incorporating microwave-safe magnets, allowing it to be stored by adhering to an interior surface (e.g., the ceiling) of the microwave oven '802 Patent, abstract '802 Patent, col. 2:46-53 The design also aims to improve cooking performance with features like vents to release steam and leg posts to permit airflow around the cover Compl. ¶21 '802 Patent, col. 4:32-44
• Technical Importance: The invention provides a practical solution to the dual problems of effective splatter containment during cooking and convenient, out-of-the-way storage for a common kitchen accessory Compl. ¶23

Key Claims at a Glance

• The complaint asserts infringement of independent claims 1 and 12 Compl. ¶45
• Independent Claim 1 requires, among other elements:
  • A housing member with an open end and an outer rim for support.
  • At least one ventilation portion to permit air flow.
  • A set of leg posts protruding from the outer rim to facilitate air flow.
  • At least one magnetic member integrated into the housing, comprising a magnet and an "enveloping member."
  • The enveloping member comprises "one of a metal foil or metallic coating configured to shield the magnet during microwave cooking."
• Independent Claim 12 requires, among other elements:
  • A housing member with a "closed end" and a lower portion with an "open end."
  • At least one magnetic assembly integrated into the "closed end" of the housing.
  • The magnetic assembly comprises a magnet member and an "enveloping member."
  • The enveloping member comprises "one of a metal foil or metallic coating configured to shield the magnet member during microwave cooking."
• The complaint reserves the right to assert several dependent claims Compl. ¶45

III. The Accused Instrumentality

Product Identification

• The "HomeCraft, 12-inch Microwave Plate Cover Shield with Magnets" (the "Accused Product") Compl. ¶36

Functionality and Market Context

• The complaint describes the Accused Product as a plastic, dome-like object designed to cover plates of food during microwave cooking Compl. ¶48 Functionally, it is alleged to incorporate features that map directly to the patent claims, including ventilation strips, four leg posts on its outer rim, and four magnets integrated into its top surface Compl. ¶¶50-53 An advertisement for the Accused Product, included as Image 7 in the complaint, shows it magnetically adhering to the interior roof of a microwave for storage Compl. ¶54 Compl. p. 15, Image 7 The complaint also states that metallurgical testing revealed the magnets are neodymium with a zinc coating that envelops them Compl. ¶¶44, 55

IV. Analysis of Infringement Allegations

'802 Patent Infringement Allegations (Claim 1)

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A cover member assembly for use in a microwave oven comprising: a housing member configured for covering a food item during microwave cooking...	The Accused Product is a "plate cover shield" described as keeping a microwave safe from food splatter while heating food.	¶47; ¶48	col. 4:19-22
...the housing member with an open end having an outer rim adapted to support the housing member in a face-down configuration...	The Accused Product has an open end and an outer rim that allows it to be placed over a plate of food. An image shows the product's 12-inch diameter fitting over plates and bowls.	¶49; p. 10, Image 2	col. 4:32-37
...the housing further including at least one ventilation portion to permit air flow...	The Accused Product contains a plurality of cut-out strips in its top dome structure, advertised as "Ventilation Holes" that allow moisture to escape.	¶50; p. 11, Image 3	col. 4:41-44
...wherein the outer rim includes a set of leg posts protruding therefrom configured to facilitate air flow up through the housing member...	The Accused Product includes four leg posts on its outer rim, which are alleged to create a void to facilitate air flow when the product is in a face-down configuration.	¶52; p. 14, Image 6	col. 4:35-41
...and at least one magnetic member integrated into the housing member, the at least one magnetic member configured to facilitate adhering of the housing member to an interior surface of a microwave oven...	The Accused Product has four magnetic strips integrated into its top structure that enable it to magnetically adhere to the roof of a microwave oven for storage.	¶53; ¶54	col. 4:45-49
...the at least one magnetic member comprising a magnet and an enveloping member...	Metallurgical testing allegedly shows the magnets are comprised of a neodymium magnet and a zinc coating that completely envelops it, which are identified as the "magnet" and "enveloping member," respectively.	¶55	col. 6:51-56
...wherein the enveloping member further comprises one of a metal foil or metallic coating configured to shield the magnet during microwave cooking of the food item.	The complaint alleges the zinc coating is a metal, and that this metallic coating shields the magnets during cooking.	¶56	col. 6:55-56

'802 Patent Infringement Allegations (Claim 12)

Claim Element (from Independent Claim 12)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a cover member for use in a microwave oven comprising: a housing member configured for covering a food item during microwave cooking...	The Accused Product is marketed as a "plate cover shield" for use in a microwave.	¶58	col. 2:54-55
...the housing member having a closed end and a lower portion with an open end...	The Accused Product is described as a dome-shaped object with a hollow interior, where the top or apex of the dome constitutes the "closed end" and the bottom constitutes the "open end."	¶60	col. 2:1-3
...and at least one magnetic assembly integrated into the closed end of the housing...	The Accused Product has four magnets integrated into the closed end or apex of its dome-like structure.	¶61	col. 2:2-3
...the at least one magnetic assembly configured to facilitate adhering of the housing member to an interior surface of the microwave oven...	The magnetic strips on the closed end of the Accused Product's structure enable it to magnetically adhere to the interior of microwave ovens.	¶62	col. 2:3-6
...the at least one magnetic assembly comprising a magnet member and an enveloping member...	The magnetic assembly is alleged to comprise a magnet (neodymium) and an enveloping member (a zinc coating that fully envelops the magnet).	¶63	col. 6:51-56
...wherein the enveloping member further comprises one of a metal foil or metallic coating configured to shield the magnet member during microwave cooking of the food item.	The zinc coating is alleged to be a metallic coating configured to shield the magnet member during microwave cooking.	¶64	col. 6:55-56

Identified Points of Contention

• Scope Questions: The core dispute appears to center on the claim term "enveloping member". The complaint notes that Nostalgia previously argued its product's zinc plating was "integrated into the magnet" and not a "distinct enveloping member," suggesting a potential defense that a coating is not an "enveloping member" in the sense required by the claim Compl. ¶68 This raises the question: Does the term "enveloping member", as claimed, read on a metallic plating that is applied directly to the magnet, or does it require a structurally distinct component?
• Technical Questions: A potential evidentiary question is whether the zinc plating on the Accused Product is, in fact, "configured to shield the magnet" from microwave energy. The complaint asserts this is the case but does not provide specific evidence beyond identifying the material as zinc Compl. ¶56 Compl. ¶64 The effectiveness of this shielding may become a point of technical dispute.

V. Key Claim Terms for Construction

• The Term: "enveloping member"
• Context and Importance: This term appears central to the dispute, as the complaint alleges Nostalgia's pre-suit defense hinged on its interpretation of this term Compl. ¶68 Nostalgia allegedly switched from a separate aluminum foil wrap to a zinc plating and argued this redesign took its product outside the patent's scope. The court's construction of whether a "plating" can constitute an "enveloping member" may be dispositive.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claims themselves recite "one of a metal foil or metallic coating," which could suggest that a "metallic coating" is a type of "enveloping member" '802 Patent, claims 1, 12 The specification further describes an embodiment where the magnet is shielded by being a "metal coated magnet" '802 Patent, col. 6:55-56 Plaintiff will likely argue this language explicitly defines a coating as a form of the claimed member.
  • Evidence for a Narrower Interpretation: The specification also includes figures and descriptions of a multi-part physical assembly, where an "enveloping or encasing member 222" is formed by two plastic halves (222A and 222B) that snap-fit together to enclose the magnets '802 Patent, col. 6:49-55 '802 Patent, Fig. 4A A defendant could argue these more detailed embodiments define the term as a structurally separate component that encases the magnet, not a mere surface treatment.

VI. Other Allegations

• Indirect Infringement: The complaint alleges inducement by asserting that Nostalgia actively encourages and instructs third parties, such as retailers and end users, to use and sell the Accused Product in a manner that infringes Compl. ¶77 It also pleads contributory infringement, alleging the product is a material part of the invention and has no substantial non-infringing use Compl. ¶78
• Willful Infringement: Willfulness allegations are heavily emphasized and are based on the parties' prior business relationship. The complaint alleges that Nostalgia had actual notice of the patent as of January 2022, entered into a license agreement, unilaterally terminated that agreement, and then continued to sell the Accused Product with full knowledge of the patent Compl. ¶79 The complaint characterizes Nostalgia's argument about its "redesigned" product as "objectively baseless" Compl. ¶69 Compl. ¶79

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

This case appears poised to turn on a combination of claim construction and the factual record of the defendant's conduct. The central questions for the court will likely be:

• A question of definitional scope: Can the term "enveloping member", which the patent describes as both a physical casing and a "metallic coating," be construed to read on the integrated zinc plating found on the accused product's magnets, or does the term require a structurally distinct component?
• A question of intent and willfulness: Given the prior licensing agreement, did the defendant's decision to terminate the license and sell a "redesigned" product constitute willful infringement based on knowledge that the product remained infringing, or was it a good-faith, albeit potentially incorrect, belief that the design change moved the product outside the patent's scope?