IP Law Daily, PATENT—E.D. Va.: Declaratory judgment inappropriate in patent dispute involving interlayer film inventions, (May 19, 2026)

By Carolin Dennis, B.Sc., LL.B., LL.M.

The plaintiff’s complaint for declaratory judgment failed to demonstrate that a substantial controversy of sufficient immediacy and reality exists to warrant declaratory judgment relief.

The federal district court in Norfolk, Virginia, granted Sekisui Chemical Co., Ltd.’s motion to dismiss the suit filed by Kuraray America Inc. seeking to declare Sekisui’s patents covering interlayer film for laminated glass invalid. The district court found that Kuraray America did not demonstrate that a substantial controversy of sufficient immediacy and reality exists to warrant declaratory judgment relief, and even if it did, the district court would exercise its discretion to decline to entertain this case (Kuraray America Inc. v. Sekisui Chemical Co., Ltd., No. 2:25-cv-00589-JKW-DEM (E.D. Va. May 12, 2026)).

Background. Kuraray Co., Ltd (Kuraray Co.) is a Japanese entity with business in 32 countries, including in the United States through Kuraray America, a subsidiary. Kuraray Co. manufactures and sells products in the interlayer film industry, including Trosifol® The Wedge Acoustic and Trosifol® The Wedge Acoustic Shadeband, which are manufactured by Kuraray Europe and Kuraray Korea, and then either directly sold or exported to other Kuraray entities to sell. Kuraray America sells these products in North America. Sekisui Chemical Co., Ltd. (Sekisui) holds patents related to interlayer film inventions, including: (1) Patent Family A, which encompasses 20 patents issued from 11 patent offices, spanning 16 jurisdictions, stemming from International Patent Publication No. WO2007/132777 and (2) Patent Family B, which encompasses 13 patents issued from 10 patent offices, spanning 16 jurisdictions, stemming from International Patent Publication No. WO2017/057497.

On July 30, 2024, Sekisui sent a warning letter to Kuraray Co. stating that the products manufactured and sold by Kuraray Co., at a minimum, ‘Trosifol® The Wedge Acoustic’ and ‘Trosifol® The Wedge Acoustic Shadeband’ fall within the technical scope of Sekisui’s patents. Therefore, the manufacture and sale of Kuraray Co. products constitutes an infringement of Sekisui’s patents. The letter asserted that Sekisui would “be forced to consider legal action” if Kuraray Co. did not meet certain demands within 10 business days. Kuraray Co. did not respond. Thereafter, the parties engaged in a series of legal actions. Within two months of sending the warning letter to Kuraray Co., Sekisui filed enforcement actions in Korea and Germany; but since September 2024 it has not brought any additional related enforcement actions.

On September 17, 2025, Kuraray America initiated a case against Sekisui, seeking a declaratory judgment of the invalidity of six U.S. patents—five from Patent Family A and one from Patent Family B. Sekisui file a motion to dismiss under Fed. R. Civ. P. 12(b)(1).

Declaratory judgment claims. In deciding whether to entertain a declaratory judgment request, a court must determine whether resolving the case serves the objectives of the Declaratory Judgment Act (DJA), whether the facts alleged, under all the circumstances, show that, there is a substantial controversy, between parties having adverse legal interests, of sufficient immediacy and reality to warrant the issuance of a declaratory judgment. The question of whether an actual case or controversy exists with respect to a declaratory judgment of noninfringement or invalidity of a patent is governed by Federal Circuit law, the district court noted. Further, to establish a case or controversy, “more is required than communication from a patent owner to another party, merely identifying its patent and the other party’s product line,” but “how much more is required is determined on a case-by-case analysis.”

Case or controversy requirement. Kuraray America alleged that a substantial controversy exists between the parties because of (1) the warning letter and (2) Sekisui’s 2024 patent infringement lawsuits in Germany and Korea, and because (3) Sekisui “has made no commitment to forego patent enforcement actions in the United States.” Therefore, Kuraray America represents that it filed its complaint “to continue its domestic operations without the fear of litigation.”

Sekisui contended that the warning letter was too generic to constitute an identification of any specific patents that would give rise to a substantial controversy. However, the district court noted that the warning letter identified a specific patent family that included five U.S. patents, as well as specific products that Kuraray America sold. In other words, the letter identified specific patents, products, and demands, and unambiguously gave Kuraray Co. the option of either ceasing sales of the specific products or facing legal action. However, the timeline and the history of litigation between the parties here showed that there is no “immediacy and reality” to establish a sufficient controversy.

The district court noted that Kuraray America did not allege that Sekisui has a history of litigating its patents in the U.S., that it has directed any actions toward Kuraray America as distinct from Kuraray Europe or Korea, nor that it has communicated with or alluded to Kuraray America in any communications apart from the July 2024 warning letter to Kuraray Co. referencing “various countries under WO2007/132777.” Furthermore, International Patent Publication No. WO2007/132777, which covers Patent Family A, contains 20 patents in 16 jurisdictions, of which Sekisui only chose to enforce three patents in two jurisdictions. Given Sekisui’s limited enforcement effort almost two years ago, the reference to ‘various countries under WO2007/132777’ is not alone enough to establish immediacy or reality. Therefore, Kuraray America’s conclusive assertion that Sekisui’s actions in Germany and Korea “make the United States the next step” was devoid of support.

Lastly, that Sekisui has not “provided any assurance” such as “a covenant not to sue or a declaration of invalidity” in the United States did not impact the jurisdictional analysis because Kuraray America has not alleged that it has asked for such an assurance.

Discretion under the DJA. Kuraray America argued that the action “will serve a useful purpose in clarifying and settling the legal relations in issue” because Sekisui’s conduct has “infected Kuraray America’s business with uncertainty and insecurity.” However, the complaint was devoid of allegations that Kuraray America faces a real choice between “either abandoning its products or running the risk of being sued for infringement.” Therefore, even if this case satisfied subject matter jurisdiction under the DJA, the district court determined that it would exercise its discretion to decline to hear it because “courts should exercise their discretionary jurisdiction with caution when doing so would raise serious questions about Article III jurisdiction, as this case does.”

Accordingly, Sekisui’s motion to dismiss was granted and the case was dismissed.

The Case is No. 2:25-cv-00589-JKW-DEM.

Judge: Walker, J.

Attorneys: Jon Myer Talotta (Hogan Lovells US LLP) for Kuraray America Inc. Andrew Kutas (Venable LLP) for Sekisui Chemical Co., Ltd.

Companies: Kuraray America Inc.; Sekisui Chemical Co., Ltd.

Cases: Patent VirginiaNews