The duplicative-litigation doctrine prevents plaintiffs from “maintain[ing] two separate actions involving the same subject matter at the same time in the same court . . . against the same defendant.” Walton v. Eaton Corp., 563 F.2d 66, 70 (3d Cir. 1977) (en banc).

In patent infringement cases, whether patent-infringement complaints involve the same subject matter (such as the extent of factual overlap) is determined under Federal Circuit law. Senju Pharm. Co. v. Apotex Inc., 746 F.3d 1344, 1348 (Fed. Cir. 2014).

Two primary “areas of factual overlap” to consider in this analysis are: (1) “the overlap of the product[s] . . . accused in the instant action with the product[s] . . . accused in the prior action”; and (2) the overlap of the patents in both suits. Senju Pharm., 746 F.3d at 1348.

Arendi Patent Litigation

In Arendi S.A.R.L. v. LG Electronics Inc., No. 21-1967, — F.4th — (Fed. Cir. Sept. 7, 2022), the plaintiff, Arendi, initially accused hundreds of LG products of patent infringement under the D. Del. Default Standard for Discovery § 4(a), but provided claim charts with respect to only one of those products, LG's Rebel 4 phone, under the D. Del. Default Standard for Discovery § 4(c).

Two months after Arendi filed its Section 4(c) Disclosure, LG sent a letter to Arendi stating that Arendi's singular-product claim charts for the '843 patent under Section 4(c) and thus “LG underst[ood] Arendi's infringement contentions [for the '843 patent] to be limited to” the Rebel 4 product.

Several months later, in October 2019, in response to an interrogatory, LG reiterated its “position that Arendi has only provided infringement contentions for [the Rebel 4].”

Yet Arendi did not move to supplement its Section 4(c) Disclosure.

After the close of fact discovery in December 2019, Arendi provided its expert report in August 2020, and LG successfully moved to strike the portions of that report concerning infringement contentions against non-Rebel 4 products. In view of LG's repeated assertion that “LG understood Arendi was accusing only the Rebel 4,” the Delaware district court found that Arendi “failed to fulfill its discovery obligations” in not supplementing its Section 4(c) disclosures.

Arendi then filed a new patent infringement lawsuit against the non-Rebel-4 products (“Arendi II”).

LG successfully moved to dismiss the new complaint as duplicative since all of the non-Rebel-4 products in Arendi II had been accused in the earlier lawsuit.

Federal Circuit Appeal of Arendi II

On appeal, Arendi argued there was no overlap between the accused products because the district court had granted LG's motion to strike parts of Arendi's expert report in the earlier lawsuit.

According to Arendi, the district court determined that Arendi had not sufficiently disclosed its intent to accuse the non-Rebel 4 products in Arendi I such that those products were effectively not at issue. . . . And under this logic, Arendi maintains, there is no accused-product overlap: . . . Arendi I involves only LG's Rebel 4 phone.

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          But Arendi misunderstands (if not misrepresents) the district court's Arendi I order. As the district court explained when dismissing the Arendi II complaint, although Arendi insists the district court “ruled” that the non-Rebel 4 products “had not been accused in Arendi I,” “[t]hat is not correct.” J.A. 54 (italics added). The court did not grant LG's motion to strike parts of Arendi's infringement expert report because Arendi failed to sufficiently accuse the nonRebel 4 products. The court granted the motion to strike because Arendi “failed to fulfill its discovery obligations” with respect to those products, so Arendi's infringement allegations in its expert report were procedurally untimely. J.A. 1576–77.

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          Left with the simple and obvious fact that the non-Rebel 4 products accused in Arendi II are identical to products accused in Arendi I, we determine that the district court did not err in dismissing the Arendi II complaint as improperly duplicative.

In a footnote, the Federal Circuit recognized that an argument can be made that the duplicative-litigation doctrine here “concerns an understanding of the case's procedural history and the application of local rules rather than an issue peculiar to patent law.” Nonetheless, “the result would be the same either way.”

The Federal Circuit affirmed the Delaware district court's dismissal of the later-filed complaint as improperly duplicative.

The patent attorneys at Thomas P. Howard, LLC prosecute and litigate patents nationwide including in Colorado.